105

PART 5: EQUIPMENT DESIGN AND DEVELOPMENT

5.1 INTRODUCTION TO SAFE DESIGN FOR HC REFRIGERANTS

5.1.1 Integrated safety 

Careful consideration of the design and construction of systems and installations is essential for achieving a high level of safety for systems. Whether the system is a stand-alone appliance or a large installed 

centralised system, the principle of integrated safety should be applied, regardless. Through this, the 

flammability hazard is dealt with using a mixture of ignition prevention measures and, if the ignition 

risk cannot entirely be avoided, techniques for protection against the consequences of ignition. 

When a flammability hazard has been identified, a systematic approach must be taken to minimise the 

risk. This comprises three main steps: firstly, if possible, prevent the formation of flammable atmospheres; secondly, prevent the ignition of any flammable atmospheres that might occur; and finally, 

limiting the range of flames and pressures to a minimum were ignition to occur. This approach must be 

integrated into the design and operation of any RAC equipment using HC refrigerants, based around the 

procedure in Figure 21.

Figure 21: Flow chart indicating the design steps to integrate flammable substances safely
106

According to Figure 21, the first step is to avoid as practicably as possible, the occurrence of a flammable 

atmosphere:

• It is known that an HC refrigerant is being used, and therefore the flammable characteristics are 

needed to understand its behaviour in the event of a release.

• Since a flammable atmosphere can occur, it is necessary to identify the parts of the equipment or the 

installation where a flammable region may be present in the event of a release. It is a common approach to estimate the likelihood that a particular region may experience a flammable mixture. Each 

region should be characterised according to the probability or frequency of the presence of a flammable 

mixture and the extent and persistence of that flammable mixture. 

• The extent of any flammable regions should be eliminated entirely if at all possible; otherwise the 

amount present should be kept to the minimum practicable. This includes the flammable material 

being, suitably contained, prevent a release from spreading, ensuring that the contents of containers 

and pipes are clearly identifiable and adopting other practical measures, such as detection of potentially 

flammable atmospheres, alarm procedures and appropriate ventilation. 

The second step is the elimination of potential sources of ignition:

• Ignition can be caused by high energy sources such as electrical discharges and hot surfaces. Therefore 

it is important to identify when and where potential sources of ignition could occur and to analyse the 

area. Particular attention should be given to electrical or mechanical equipment, although there are 

many other potential ignition sources to which consideration must be given.

• Once the ignition potential of the flammable gas and the likelihood of flammable regions are known, 

the appropriate protection can be applied to the electrical and mechanical equipment.

The third step is limiting the severity of consequences of an ignition event:

• If there is a residual risk of ignition, the maximum pressure development and the extent of any flames 

and radiated heat should be evaluated, which may necessitate using numerical or experimental methods. 

• Adopt one or more of the possible methods of protection against overpressure and flame spread, such 

as venting, suppression, containment and isolation.

These fundamental concepts can be directly applied to the case of HCs in RAC systems and equipment:

• Step 1: consider the possibility of refrigerant leakage and how to avoid or minimise it, reduce the 

charge size of the system, and/or the amount that may be released into a particular area, use ventilation, gas detection and associated controls

• Step 2: identify all the potential sources of ignition and remove or ensure they are protected against 

ingress of refrigerant in the event of a leak

• Step 3: ensure that all housings or enclosures have venting or otherwise eliminate the possibility of 

refrigerant entering them, and use marking and instructions to raise the awareness of those who may 

come into contact with the system and refrigerant

Furthermore, equipment must be designed and manufactured after due analysis of possible operating 

faults in order to preclude dangerous situations as far as possible, and any misuse which can reasonably 

be anticipated must be taken into account. When equipment is subject to special checking and maintenance conditions must be designed and constructed with such conditions in mind and must be so 

designed and constructed as to be capable of coping with actual or foreseeable surrounding area conditions. Wherever possible, if there is a possibility of a release of flammable gas, enclosed structures may be 

employed so that a release will not give rise to a flammable atmospheres outside the equipment. If 

equipment is within a housing or a locked container, it must be possible to open such housing or container only with a special tool or by means of appropriate protection measures.
107

APPLICATION OF ATEX EQUIPMENT DIRECTIVE

For products being sold within Europe, the EU ATEX “equipment” directive (94/9/EC concerning 

equipment and protective systems intended for use in potentially explosive atmospheres) must 

be considered for all equipment which are capable of causing an explosion through their own 

potential sources of ignition. (However, equipment intended for use in domestic and non-commercial environments is broadly exempt.) The means of conformity depends upon the type of 

equipment and the manner of its application and use. 

Most RAC equipment may correspond to equipment Group II, Category 3, i.e., designed to be 

capable of functioning in conformity with the operating parameters established by the manufacturer and ensuring a “normal” level of protection, where it is intended for use in areas in 

which explosive atmospheres are unlikely to occur or, if they do occur, are likely to do so only 

infrequently and for a short period only and therefore must ensure the requisite level of 

protection during normal operation.

Equipment in this category must comply with the relevant Essential Safety Requirements 

(ESRs). This means that the equipment must be so designed and constructed as to prevent 

foreseeable ignition sources which can occur during normal operation, including taking 

account of the following:

• Principles of integrated explosion safety

• Any misuse which can reasonably be anticipated must be taken into account.

• Special checking and maintenance conditions

• Surrounding area conditions

• Marking and instructions

• Selection of materials

• Design and construction (enclosed structures and prevention of leaks, additional means of 

protection, safe opening, overloading of equipment)

• Potential ignition sources

• Hazards arising from external effects

If the equipment does fall under ATEX then compliance with the ESRs is needed, the process 

for which is summarised in the Figure below. This is achieved through conformity to either 

one of the modules: 

• Internal control of production 

(self-certification; see info box in 

this Part), or 

• Unit verification (i.e., using a 

notified body) 

Alternatively, any other module that 

specifies stricter requirements may 

be used, most of which require 

third-party involvement.

Figure indicating the means to meet 

the essential safety requirements

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APPLICATION OF ATEX EQUIPMENT DIRECTIVE 

For products being sold within Europe, the EU ATEX “equipment” Directive (94/9/EC concerning 

equipment and protective systems intended for use in potentially explosive atmospheres) must 

be considered for all equipment which are capable of causing an explosion through their own 

potential sources of ignition. (However, equipment intended for use in domestic and noncommercial environments is broadly exempt.) The means of conformity depends upon the type 

of equipment and the manner of its application and use. 

Most RAC equipment may correspond to equipment Group II, Category 3, i.e., designed to be 

capable of functioning in conformity with the operating parameters established by the 

manufacturer and ensuring a “normal” level of protection, where it is intended for use in areas in 

which explosive atmospheres are unlikely to occur or, if they do occur, are likely to do so only 

infrequently and for a short period only and therefore must ensure the requisite level of 

protection during normal operation. 

Equipment in this category must comply with the relevant Essential Safety Requirements 

(ESRs). This means that the equipment must be so designed and constructed as to prevent 

foreseeable ignition sources which can occur during normal operation, including taking account 

of the following: 

 Principles of integrated explosion safety 

 Any misuse which can reasonably be anticipated must be taken into account. 

 Special checking and maintenance conditions 

 Surrounding area conditions 

 Marking and instructions 

 Selection of materials 

 Design and construction (enclosed structures and prevention of leaks, additional means of 

protection, safe opening, overloading of equipment) 

 Potential ignition sources 

 Hazards arising from external effects 

If the equipment does fall under ATEX then compliance with the Essential Safety Requirements 

(ESRs), the process for which is summarised in the Figure below. This is achieved through 

conformity to either on of the modules: 

 Internal control of production (self-certification; see info box in this Part), or 

 Unit verification (i.e., using a notified body) 

The following sections address these aspects in detail. Much of the direction is taken from the relevant 

safety standards, but these following sections in addition attempt to provide further insight to the rules 

and give additional safety measures.
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5.1.2 Other safety considerations

It should be noted that whilst the information provided is largely specific to the use of HC refrigerants, it 

is important to recognise that there are many other aspects that the system designer must consider with 

respect to general refrigeration safety. Although not necessarily covered within this handbook, the 

following aspects should also take a high priority in the consideration of the design of any RAC system 

and associated installation:

• General electrical safety

• Electromagnetic compatibility

• Protection against moving parts

• Protection against excessive noise

• Safety in coldrooms and other areas with controlled atmospheres

• The design, testing, selection and installation of heat exchangers, pressure vessels, compressors, pumps, 

valves and other ancillary components

• The design, testing, sizing and installation of pipework and pipe-to-pipe joints and pipe-to-component 

connections, layout, use of supports and general protection

• Arrangement and setting of pressure relief and pressure limiting devices

• Provision of marking signage and documentation

In order to address these properly, the relevant safety regulations, standards and codes must be referred 

to. Standards such as IEC 61160 on design review can provide guidance in terms of ensuring that all the 

important aspects are taken into account.

INTERNAL CONTROL OF PRODUCTION

Any manufacturer/producer of equipment must document the development and production 

process so they may demonstrate the level of safety that has been achieved; in some countries, this is mandatory by law. This procedure is where the manufacturer/producer ensures 

and declares that the equipment satisfies the necessary safety requirements applicable to it, 

that is a written declaration of conformity. Supporting this declaration, the manufacturer/

producer must establish the technical documentation (as detailed below) and must keep it at 

the disposal of the relevant authorities for inspection purposes (typically for a period ending 

at least 10 years after the last piece of equipment was manufactured). The technical documentation will enable the conformity of the equipment with the relevant requirements of the 

rules to be assessed. It must cover the design, manufacture and operation of the product, as 

follows:

• A general description of the equipment

• Conceptual design and manufacturing drawings and schemes of components, 

sub-assemblies, circuits, etc

• Descriptions and explanations necessary for the understanding of said drawings and 

schemes and the operation of the equipment

• A list of the standards applied in full or in part, and descriptions of the solutions adopted 

to meet the safety aspects of the safety requirements where the standards have not been 

applied

• Results of design calculations made, examinations carried out, etc

• Test reports

The manufacturer/producer must keep a copy of the declaration of conformity with the technical documentation. In particular, the manufacturer/supplier must take all measures necessary 

to ensure that the manufacturing process guarantees compliance of the manufactured equipment with the technical documentation referred to above and with the relevant safety requirements applicable to such equipment.
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5.2 AVOIDANCE OF LEAKAGE

5.2.1 Introduction

It is essential to avoid refrigerant leakage for both safety and environmental reasons. In terms of safety if 

the likelihood of a refrigerant release can be minimised, then the flammability risk is reduced accordingly. With regards to environmental impact, although HCs have zero ODP and negligible GWP, the 

loss of refrigerant from a system will lead to a reduction in system efficiency and cooling capacity, thus 

increasing energy consumption in two respects. Depending upon the type of system, a deficit of a few 

grammes of refrigerant charge can increase energy consumption by several percent. In addition, design 

temperatures of the cooling system may no longer be achievable, and there are further financial implications associated with the replacement of the lost refrigerant and the repair work.

Avoidance of refrigerant leakage can be achieved by addressing various stages of system handling:

• Appropriate system design and selection of appropriate components and layout

• Suitable installation and tightness testing/leak checking practices

• Regular maintenance and system checks

• Servicing by competent technicians, using proper equipment

Different types of systems tend to have different leak rates; leak rates being usually defined as the 

quantity of the leaked refrigerant as a proportion of a systems total charge per year (for example, a 

system that leaks 1 kg of its 10 kg charge in 1 year is said to have a 10% leak rate). Some typical values 

taken from various studies that monitored leak rates from a population of actual systems, are provided in 

Table 7. The variation in the leak rates is mainly a function of the design of system and the manner by 

which they are looked after. It is important to be aware that it is possible – if designed and maintained 

well – for a system to have a leak rate of zero. On the other hand, it is often the case that systems have 

leak rates of over 100%. Nevertheless, it is worth noting the types of systems that exhibit higher leak 

rates, which indicates when and where greater attention should be paid to leak minimisation. 

Table 7: Typical range of average empirical refrigerant leakage for different types of systems

Type of equipment Typical annual leakage rate (% of charge)18 

Domestic refrigeration 0.5 – 2.5%

Retail refrigeration; integral/stand-alone 1 – 5%

Retail refrigeration; split/condensing unit systems 8 – 20%

Retail refrigeration; direct expansion central systems 8 – 35%

Air conditioning; integral/portable units 0.5 – 2.5%

Air conditioning; single split systems 5 – 15%

Air conditioning; multi-split systems 5 – 20%

Air conditioning; chillers 3 – 15%

18 Report of the Refrigeration, Air Conditioning and Heat Pumps Technical Options Committee, 2006 Assessment, UNEP Nairobi, 

Ozone Secretariat, 2007; IPCC/TEAP Special Report: Safeguarding the Ozone Layer and the Climate System, Switzerland, 2005.
110

Some recent European legislation on fluorinated gases19 pays attention to the reduction of leakage from 

systems. Although this regulation does not cover HC refrigerants, it may be useful to consider some of 

its requirements in terms of reducing leakage regardless of the refrigerant type. The important parts of 

the regulation stipulate the following:

• Leak checking must be carried out with the frequency dependent upon the size of the system

• Keeping records on all systems (above a certain size), including charge size, date of leak checking, any 

remedial work, the quantities of refrigerant added and removed and the identity of the technician

• Labelling of the system with the type and quantity of refrigerant inside 

• Refrigerant must be recovered during plant servicing and maintenance and at end of life.

• Any technician working on a system must be properly training and certified with the appropriate 

qualifications 

• Company certification is required for all companies employing personnel to undertake work on 

equipment containing or designed to contain fluorinated refrigerants 

The equipment operators are under obligation to ensure that all these requirements are adhered to.

5.2.2 General system design

Some general principles may be applied to the design of a system:

• Consider the use of more than one independent refrigerant circuit, so that in the event of a major leak, 

the loss of the refrigerant would be less; this can have cost and space implication which require consideration

• Generally, with large systems, the use of automatic shut-off valves can be considered, which can be 

used to isolate parts of the refrigeration circuit (e.g., receiver, condenser, etc) when a leak is detected

• When designing pipework and selecting components, it is preferable to have as few pipe joints and 

seals (for example in valves, etc) as possible

• Ensure that all the materials that are to be used within the refrigeration system (particularly valve 

seals, o-rings, etc), are fully compatible with the HC refrigerant to be used. It is important to be aware 

that the compatibility of refrigerants with elastomers is different when different types of oils are 

involved

• Be aware that unsaturated HCs (e.g., R1270) are incompatible with certain materials that saturated 

HCs (e.g., R290) are compatible with 

• Consider the full range of operating temperatures and pressures that the materials will be subjected to, 

as this can also affect the compatibility

• Try to minimise the use of components and joints that are known to result in high levels of leakage; 

A thorough overview and additional practical tools for aiding the reduction of emissions of (any) refrigerant is provided by the Real Zero project20 of the Institute of Refrigeration, and further guidance can be 

found within the Code of Practice on Minimisation of Refrigerant Emissions21. In addition, there is a 

draft standard EN 15834:2009 on the qualification of tightness of components and joints (applicable to 

components and the entire assembly), which should be used. Of particular interest is that the standard is 

intended to characterise the tightness of the parts considering the stresses met during their operations, 

following the fitting procedure specified by the manufacturer, and also specifies the minimal information to be provided by the supplier of a component to the person in charge of carrying out the fitting 

procedure. 

19 Regulation (EC) No 842/2006 on certain fluorinated greenhouse gases

20 See www.realzero.org.uk 

21 See www.ior.org.uk/ior_publication.php?pubid=E6EM1WETAB 
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Figure 22: An indication of the tendency of different individual components to leak

5.2.3 Considerations for piping

When designing and installing pipework, a number of important considerations should be adhered to:

• Pipework and components must be protected against impact, weathering, external corrosion, and 

electrolytic corrosion at the junction of dissimilar metals

• Care must be taken to ensure that all joints are brazed correctly

• Piping should not be installed in such a way that bends or joints are stressed

• Where insulation is used, care must be taken to ensure that water does not collect at the interface of 

the tube and insulation

• Steel piping has superior properties to copper piping in respect of mechanical strength and lack of 

susceptibility to vibration and work hardening, however, steel piping is subject to external corrosion 

and must be adequately protected against it

• Pipes must be adequately supported, according to tube diameter, number of joints, weight and spacing 

distance

• Piping should not be routed where it is likely to be walked on, or used as lifting beams, where this is 

impossible, protective covers and warning labels should be provided

• Pipe runs must be designed to allow for expansion and contraction

• Piping must be designed to minimise the effects of vibration

• The need to prevent liquid hammer should be taken into account in the design of pipe routing and the 

selection of valve types

• Where the decision is taken to use quick-acting valves in long lines and means of suppressing pulsation 

must be provided

• The use of mechanical joints must be minimised; welding or brazing are the preferred jointing methods. In particular, flare joints must be avoided as they are one of the most common sources of leakage

• Wherever possible compressor connections should be made using continuous piping without the use of 

vibration eliminators or flexible connectors, providing that excessive vibration or stresses will not be 

transmitted to the rest of the system

• Where vibration eliminators or flexible connectors are required, they must be installed in strict accordance to manufacturers instructions, to ensure that they do not cause catastrophic leakage 135 

manufacturer, and also specifies the minimal information to be provided by the supplier 

of a component to the person in charge of carrying out the fitting procedure. 

Figure 22: An indication of the tendency of different individual components to leak 

5.2.3 Considerations for piping 

When designing and installing pipework, a number of important considerations should 

be adhered to: 

 Pipework and components must be protected against impact, weathering, external 

corrosion, and electrolytic corrosion at the junction of dissimilar metals 

 Care must be taken to ensure that all joints are brazed correctly 

 Piping should not be installed in such a way that bends or joints are stressed 

 Where insulation is used, care must be taken to ensure that water does not collect 

at the interface of the tube and insulation 

 Steel piping has superior properties to copper piping in respect of mechanical 

strength and lack of susceptibility to vibration and work hardening, however, steel 

piping is subject to external corrosion and must be adequately protected against it 

 Pipes must be adequately supported, according to tube diameter, number of joints, 

weight and spacing distance 

 Piping should not be routed where it is likely to be walked on, or used as lifting 

beams, where this is impossible, protective covers and warning labels should be 

provided 

 Pipe runs must be designed to allow for expansion and contraction 
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5.2.4 Considerations for major system components

When designing and installing other system components, a number of important considerations should 

be adhered to:

• Heat exchangers must be protected against possible mechanical damage

• Heat exchangers containing water must be protected against freezing.

• Access must be provided for leak testing of compressors, evaporators, condensers and associated 

components

• Where there is a risk of refrigerant leakage into water or other heat sink fluid, a means of drawing off 

and sampling that fluid must be provided

• Lower temperature air coolers and drip trays should be completely defrosted during every defrost cycle

• Defrost controls should be designed and adjusted to avoid any unnecessary defrost operations, to 

minimise thermal stresses

• Heat exchangers containing water must be protected against freezing

• Compressors should be installed on anti-vibration mountings

5.2.5 Considerations for valves

The following should be considered when selecting and choosing valves:

• Sufficient valves must be provided to ensure that servicing and maintenance can be carried out without 

causing significant loss of refrigerant

• Care is required to avoid unsafe pressures in isolated circuit sections containing liquid refrigerant.

• Where reasonably practicable, valves which have a bellows or a diaphragm instead of a spindle seal 

should be used

• Valves which have O-ring spindle seals should be used in preference to valves with spindle packing 

glands provided that the O-ring material is suitable for the temperatures and fluids involved

• Where suitable elastomeric material is not available, packed glands may be used

• Seal caps should always be fitted to all valves 

• Whenever possible, the safety valve or other device which protects the high pressure side of the refrigeration circuit should be vented to the low pressure side and not directly to atmosphere, but maintenance access to the device must be possible without the use of intervening stop valves

• The low pressure side of the system should be vented to atmosphere

• The high pressure side of the system must not be protected by a bursting disc venting to atmosphere

• Dual relief valves should be encouraged to facilitate rapid change over at mandatory service intervals 

and to sustain plant operation

• An indicating device should be fitted to the outlets of valves so that a check can be made, during 

maintenance, whether the valves has discharged to atmosphere

5.2.6 Leak detection

Leakage cannot be prevented by refrigerant detection methods, but it generally helps ensuring that 

smaller leaks do not evolve into larger leaks. A number of options are available for detection. Refer to 

Part 6.1. 
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ALTERNATIVE JOINING METHODS

It is well-know that conventional flare connections can easily develop leaks. Whilst it is 

preferable to use brazed joints, it is sometimes necessary or appropriate to make mechanical 

connections, or maybe to avoid the use of a brazing torch under certain circumstances. In 

these cases, certain other options may be considered.

“Euro-flare”

The so-called “Euro-flare” – also known as 

“solder nut” and “brazing stud” – is also a 

possible option, especially whenever screwed 

connections are necessary (for example, for 

an air conditioner outdoor/indoor unit suction/

liquid line). These are flare fittings consisting 

of a brazing adapter (tube fitting), nut and 

copper seal. In case of repair only the copper 

seal has to be changed. They come with a 

variety of different fittings. 

Ferrule compression joints (“Swagelock”)

Ferrule compression fittings are permanent 

mechanical joints. They work on the basis of 

compressing and hardening metallic materials 

within the nut onto the pipe, which provides a 

gas-tight seal and resistance against vibration. 

These are normally applied to very high pressure systems and are considered highly reliable. 

Press joints (“Lok-ring”)

Where brazing is not possible, this method 

can be a very durable and reliable option 

for tube joining and making system access 

connections. It requires the use of special 

hand tools and associated components 

(typically from 1.6 mm to 35 mm nominal 

outer diameter), and is therefore applicable 

to most domestic and small commercial 

refrigeration and air conditioning systems. 

Many different fittings are available, 

including adapters, elbows, tees, reducers, 

valves and filter-driers.
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22 Within EN 378, refrigerant charge limits are also identified according to the type of system – be it direct expansion or indirect 

(where a non-hazardous secondary heat transferring fluid is used). In this publication, this variable is accounted for by means of 

the presence of any refrigerant-containing part of the system.

5.3 REFRIGERANT CHARGE SIZE LIMITS

5.3.1 Introduction

Refrigerant charge size limits are prescribed in a number of different standards, and since the requirements amongst these standards vary, this section intends to provide a compilation of those requirements:

• EN 378

• EN / IEC 60335-2-24

• EN / IEC 60335-2-40

• EN / IEC 60335-2-89

In general, the mass of HC refrigerant within a single refrigerant circuit is limited, according to the type 

of system, the type of location and the size of the space, particularly in respect to occupied areas.22 For 

installations within human occupied spaces, a minimum room size is to be specified for a given refrigerant circuit charge size. 

Two restrictions apply to refrigerant charge sizes:

• The first is a “maximum” charge size (Mmax), which is a function of the type of location and its 

occupancy (or not)

• The second is an “allowable” charge size (Mal), which is a function of size of the (occupied) area that 

the refrigerant could leak into

The allowable charge sizes are typically based on the assumption that under the worse case, the entire 

refrigerant charge from a circuit will leak into a space almost instantaneously, and since the vapour is 

denser than air, it will partially stratify – thus the allowable charge normally accounts for this by adopting a 20% safety margin. (In certain cases, this safety margin is extended to factors approaching less 

than 5%.) On the other hand, the values for maximum charge size have been chosen on a broadly 

arbitrary basis, having little or no technical basis, although it can be seen that there is a general correspondence between lower charge sizes and the number and vulnerability of the occupants. In the case of 

systems located below ground level, a common value is applied throughout on the basis that it is difficult 

for a denser-than-air vapour to disperse upwards.

A summary of these maximum and allowable charge sizes is provided in Table 10.

In general, HC refrigerants should be used only in sealed systems with restricted charge or otherwise in 

occupancy categories where only competent members of staff are present. In any case, the refrigerant 

charge in a system with any refrigerant-containing part situated below ground level is restricted to no 

more than 1.0 kg. Sealed systems with refrigerant charge of 4 × LFL (for example, 4 × 0.038 = 0.15 kg 

for R290) or less may be sited in any location or category of occupancy provided there are no sources of 

ignition associated with the refrigerating system (LFL values are provided in Table 8 for selected common HC refrigerants).

The following sections provide a description of refrigerant charge size restrictions, according to the 

occupancy category, A, B or C, and also according to the positioning of the system and its parts:
115

• Entire system within human occupied space which is not a machinery room

• Compressor and liquid receiver in an unoccupied machinery room or in the open air

• All refrigerant containing parts in an unoccupied machinery room or in the open air

• Entire system within a specially constructed ventilated enclosure

Figure 23 is a flow chart that may be used for determining the appropriate refrigerant charge size and/or 

minimum room size for HC refrigerants.

Table 8: Flammable limits and Practical Limits of several HC refrigerants

5.3.2 Occupancy categories

The identification of the type of occupancy is critical to the determination of maximum refrigerant 

charge size. This is because in some locations, occupants may be unaware of the emergency exits or may 

find it difficult to exit the building in the event of an emergency, and in other locations, the occupants 

may be well aware of the emergency procedures. Considerations of safety in refrigerating systems take 

into account the site, the number of people occupying the site and the categories of occupancy. The 

maximum quantity of refrigerant permitted (per refrigerant circuit) is a function of these conditions. 

Thus, refrigerant charge size restrictions described are limited according to the occupancy category, A, 

B or C:

• Category A: general occupancy not restricted at all – dwellings and public places where people are 

unlikely to be aware of the refrigerant hazards

• Category B: supervised occupancy – restricted to a certain number of people, some of whom are aware 

that the system is charged with a HC 

• Category C: occupancy with authorised access only – where trained personnel operate who should be 

competent in handling refrigerant or at least aware of emergency procedures

Value R600a R290 R1270 R290/

R600a †

R290/

R170 ‡

Lower 

Flammability Limit 

(kg/m3) 0.043 0.038 0.043 0.040 0.038

(%) 1.80 2.10 2.50 1.95 2.15

Practical limit (kg/m3) 0.008 0.008 0.008 0.008 0.008

Density of vapour (kg/m3)* 2.48 1.86 1.77 2.17 1.82

† Based on 50% R290 and 50% R600a molar composition

‡ Based on 94% R290 and 6% R170 molar composition

* At standard atmospheric pressure (101.325 kPa) and 21°C
116

Table 9: Types of occupancies and examples

If there is the possibility of more than one category of occupancy, the more stringent requirements apply, 

i.e., category A is chosen in favour of category B, or category A in favour of category C. However, if 

occupancies are isolated, e.g. by sealed partitions, floors and ceilings, then the requirements of the 

individual category of occupancy apply.

5.3.3 Category A o

ccupancies (general occupancy)

General occupancy is defined in EN 378-1: 2008 as “a location where people may sleep or where the 

number of people present is not controlled or to which any person has access without being personally 

acquainted with the personal safety precautions”. A sudden loss of refrigerant should not be able to raise 

the concentration of refrigerant within the room to or above the Practical Limit (given in Table 8) in a 

human-occupied space and there shall be no sources of ignition associated with the refrigerating system 

or located in an area where the refrigerant could gather in the event of an leak. 

In all system and occupancy types below, the maximum refrigerant charge per circuit is limited to 

Mmax = 1.0 kg, if any refrigerant-containing part is situated below ground level.

Entire system in human occupied space

Where (a) the entire system is located in a human occupied space, or (b) where the compressor and 

receiver part of the system is located in an unoccupied machinery room or in the open air, but part 

of the system is located in a human occupied space, then HC refrigerants shall be permitted only in 

systems with refrigerant containing part in a general occupancy with a refrigerant charge:

• Up to the allowable refrigerant charge (Mal) detailed below (see Part 5.3.5), but not exceeding the 

maximum charge of Mmax = 1.5 kg

Occupancy Description Examples

Category A Rooms, parts of buildings, or another location where 

people may sleep, where people are restricted in 

their movement or where the number of people 

present is not controlled or to which any person has 

access without being personally acquainted with the 

personal safety precautions

Hospitals, prisons, nursing 

homes, theatres, supermarkets, transport termini, 

hotels, lecture halls, dwellings, 

restaurants, ice rinks, 

passenger vehicles, etc

Category B Rooms, parts of buildings or buildings, where only a 

limited number of people may be assembled, some of 

them being necessarily acquainted with the general 

safety precautions

Office buildings, laboratories, 

places of work, places for 

general manufacturing, etc

Category C Rooms, parts of buildings, buildings where only 

authorised persons are granted access and which is 

not open to the public and; authorised persons shall 

be acquainted with general safety precautions of the 

establishment

Non public areas in supermarkets, cold stores, manufacturing 

facilities, refineries, manufacturing facilities e.g. for chemicals, food, ice and ice cream
117

System in ventilated enclosure

Where the entire system is located within a mechanically ventilated enclosure (see Part 5.6.5), HC 

refrigerants shall be permitted only in systems with refrigerant containing part in a general occupancy 

with a refrigerant charge:

• Up to the maximum charge of Mmax = 130 × LFL (kg)

System in open air

Where the entire system located in the open air, HC refrigerants shall be permitted only in systems with 

refrigerant containing part in a general occupancy with a refrigerant charge:

• Up to the maximum charge of Mmax = 5.0 kg

5.3.4 Category B occupancies (supervised occupancy)

Supervised occupancy is defined in EN 378-1: 2008 as “rooms, parts of buildings or buildings, where 

only a limited number of people may be assembled, some of them being necessarily acquainted with the 

general safety precautions.” A sudden loss of refrigerant should not be able to raise the concentration of 

refrigerant within the room to or above the Practical Limit (given in Table 8) in a human-occupied space 

and there shall be no sources of ignition associated with the refrigerating system or located in an area 

where the refrigerant could gather in the event of an leak. 

In all system and occupancy types below, the maximum refrigerant charge per circuit is limited to 

Mmax = 1.0 kg, if any refrigerant-containing part is situated below ground level.

Entire system in human occupied space

Where (a) the entire system is located in a human occupied space, or (b) where the compressor and 

receiver part of the system is located in an unoccupied machinery room or in the open air, but part of 

the system is located in a human occupied space, then HC refrigerants shall be permitted only in systems 

with refrigerant containing part in a general occupancy with a refrigerant charge:

• Up to the allowable refrigerant charge (Mal) detailed below (see Part 5.3.5), but not exceeding the 

maximum charge of Mmax = 2.5 kg

System in ventilated enclosure

Where the entire system is located within a mechanically ventilated enclosure (see Part 5.6.5), 

HC refrigerants shall be permitted only in systems with refrigerant containing part in a supervised 

occupancy with a refrigerant charge:

• Up to the maximum charge of Mmax = 130 × LFL (kg)

System in open air

Where the entire system is located in the open air, HC refrigerants shall be permitted only in systems 

with refrigerant containing part in a supervised occupancy with a refrigerant charge:

• Up to the maximum charge of Mmax = 10.0 kg

5.3.5 Category C occupancies (authorised occupancy)

Authorised occupancy is defined in EN 378-1: 2008 as “An occupancy which is not open to public and 

where only authorised persons are granted access. Authorised persons shall be acquainted with general 
118

safety precautions of the establishment.” A sudden loss of refrigerant should not be able to raise the 

concentration of refrigerant within the room to or above the Practical Limit given (given in Table 8) in a 

human-occupied space and there shall be no sources of ignition associated with the refrigerating system 

or located in an area where the refrigerant could gather in the event of an leak. 

In all system and occupancy types below, the maximum refrigerant charge per circuit is limited to 

Mmax = 1.0 kg, if any refrigerant-containing part is situated below ground level.

Entire system in human occupied space

Where the entire system is located in a human occupied space, HC refrigerants shall be permitted only 

in systems with refrigerant containing part in an authorised occupancy with a refrigerant charge:

• Up to the allowable refrigerant charge (Mal) detailed below (see Part 5.3.5), but not exceeding the 

maximum charge of Mmax = 10.0 kg

Part of system in human occupied space

Where the compressor and receiver part of the system is located in an unoccupied machinery room, or in 

the open air, HC refrigerants shall be permitted only in systems with refrigerant containing part in an 

authorised occupancy with a refrigerant charge:

• Up to the allowable refrigerant charge (Mal) detailed below (see Part 5.3.5), but not exceeding the 

maximum charge of Mmax = 25 kg

System in ventilated enclosure

Where the entire system is located within a mechanically ventilated enclosure (see Part 5.6.5), 

HC refrigerants are permitted in systems with refrigerant containing part in an authorised occupancy 

without restriction of the refrigerant charge.

System in open air or special machinery room23 

Where the entire system is located in the open air or a special machinery room, HC refrigerants are 

permitted in systems with refrigerant containing part in an authorised occupancy without restriction of 

the refrigerant charge.

5.3.6 Calculation of allowable charge sizes (Mal)

For systems that are located in occupied spaces, but are not used for cooling or heating for human 

comfort, the allowable refrigerant charge per independent circuit is determined from:

	 	 	 	 (1)

where 

Mal = allowable mass per circuit (kg)

VRm = room volume (m3)

PL = practical limit (kg/m3); see Table 8

Conversely, for a given circuit charge size, the minimum room size can be determined from:

	 	 	 (2)

 PL 

23 Within the standard EN 378: 2008, when describing occupancies, it states “machinery rooms are regarded as unoccupied”, 

whilst in the definition of machinery rooms it states that they are “only accessible to authorised persons”. Given the ambiguity, 

machinery rooms can be considered as occupancy C.
119

For systems that are located in occupied spaces, and are to be used for cooling or heating for human 

comfort, the allowable refrigerant charge per independent circuit is determined from:

	 	 	 	 	 	 (3)

where

LFL = lower flammability limit (kg/m3)

ARm = room floor area (m2)

h = some nominal height (m), according to the position of the equipment:

• h = 0.6 m for floor mounted

• h = 1.0 m for window mounted

• h = 1.8 m for wall mounted

• h = 2.2 m for ceiling mounted

Conversely, for a given circuit charge size, the minimum room floor size can be determined from:

	 	 	 	 	 	 	 	 	 	 	 	 	 (4)

For a particular sub-category of equipment, non-fixed (portable) factory sealed single package air 

conditioners or heat pumps, the allowable refrigerant charge per independent circuit is determined from:

	 	 	 	 	 	 	 	 	 	 	 	 	 (5)

This is provided that the charge size of no greater than 8 m3

 × LFL (approximately 300 g for HC 

refrigerants). There are additional requirements applied to this type of equipment, such as when the 

appliance is switched on, a fan must operate continuously supplying a minimum airflow as under normal 

steady state conditions, even when the compressor is switched off by the thermostat.

5.3.7 Equipment airflow24 

In order to reduce the risk of ignition of leaked refrigerant – especially within an enclosed area – the fan 

associated with the equipment (for example, the air handler or condenser fans) located in the enclosed 

area should have a minimum airflow rate, corresponding to:

	 	 	 	 	 	 	 	 	 	 	 	 	 (6)

 

where

Vaf = volume airflow of fan(s) (m3/s)

M = refrigerant charge (kg)

LFL = lower flammability limit (kg/m3); from Table 8

This is a generalised approximate formula which is based on measurements over a range of conditions, 

and therefore may not be accurate for all situations. It is also noted that the effectiveness of mixing is 

24 Note that this is not a requirement of any standard, but is considered to add additional means of improving safety levels

.
120

also a function of the exit velocity, so a smaller air discharge area will provide improvements. 

ADDRESSING CHARGE SIZE LIMITS

It is known that some of the calculations for charge size limits within the safety standards, 

as detailed here, can be very restrictive, sometimes with good reason, sometimes without. If 

there is a certain need for higher charge sizes, then consider certain approaches:

• Use two independent refrigerant circuits rather than one

• Use indirect refrigerant circuits so that the refrigerant charge may be kept in a location 

away from the occupied space

• Use a safety system, where if there is a leak, a limited quantity of refrigerant may be 

released into the occupied space, whilst retaining the remaining refrigerant within an 

external (outside or occupancy C) part of the system. If this type of approach is being used, 

ensure that the mechanism is tested and its reliability proved, and carrying out a thorough 

risk assessment to confirm that under no circumstances will a failure lead to a flammable 

atmosphere being created in a location that hasn’t already been designed to handle it. 

On the whole, standards are not regulations, and therefore they do not necessarily impose 

legal requirements (unless stated by a legally-binding contract). Furthermore, standards tend 

to lag technological developments (rather than lead them) so they can often be oblivious of 

new technologies, methods or techniques that could be employed to achieve a similar or 

greater level of safety. In such cases, it may be necessary to develop risk assessments and 

approvals from third-parties to enable the adoption of approaches that deviate from the 

standards. Since the drafting of standards is often dominated by enterprises that favour 

specific technology options in preference to others, standards may reflect these preferences 

whilst inhibiting others. In these cases, the new or alternative technologies, methods or 

techniques should be fed into the standards making process to enable them to become more 

inclusive.
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Location of

refrigerant

containing parts

System 

type

Refrigerant 

mass †

Occupancy type

Category A (general occupancy) Category B (supervised occupancy) Category C (occupancy with authorised access only)

RHPAC Comfort HPAC RHPAC Comfort HPAC RHPAC and Comfort HPAC

Human occupied space which is not a machinery room

Direct Allowable

M( al)

PL × VRm 2.5LFL1.25h ARm

or 0.5ARmLFL

PL × VRm 2.5LFL1.25h ARm

or 0.5ARmLFL

PL × VRm

Maximum

(Mmax)

1.5 kg, or 1 kg BG 26 × LFL, or 1 kg BG 2.5 kg, or 1 kg BG 26 v LFL, or 1 kg BG 10 kg (or 25 kg*), or 1 kg BG

In an unoccupied machinery room or in the open air or a special ventilated enclosure Indirect Allowable M( al) 5 kg, or 1 kg BG 130 × LFL, or 1 kg BG 10 kg, or 1 kg BG 130 × LFL, or 1 kg BG No limit, or 1 kg BG

Maximum 

M( max )

5 kg, or 1 kg BG 130 × LFL, or 1 kg BG 10 kg, or 1 kg BG 130 × LFL, or 1 kg BG No limit, or 1 kg BG

Notes:RHPAC = Refrigeration, heat pumps and air conditioningComfort HPAC = heat pumps and air conditioning (specifically for human comfort)Allowable and maximum refrigerant charge sizes in kg BG = below ground; note that refrigerant charges above 1 kg are not permitted below ground, including interconnecting pipework or other refrigerant-containing parts* 25 kg if compressor and liquid receiver are in an unoccupied machinery room or in the open air† Circuits containing ≤ 0.15 kg do not apply and can be sited in any locations

Table 10: Summary of maximum and allowable refrigerant charge sizes according to EN 378, and EN / IEC 60335-2-24, -89 and -40
122

Figure 23: Determination of maximum charge amount and room size for HC refrigerants
123

5.4 CHARGE SIZE REDUCTION 

5.4.1 Introduction

The reduction of refrigerant charge mass is a very important consideration in the design and construction of systems using HC refrigerants. Assuming that all other factors are the same, a greater charge size 

results in a higher risk of ignition, and therefore a reduced refrigerant charge will achieve a higher level 

of safety for a system. There are additional benefits to be gained from smaller charge sizes, such as from a 

cost perspective; not only because less quantity of refrigerant is required, but a smaller internal volume 

normally corresponds to less construction material (i.e., metal). Furthermore, smaller charges can 

improve system efficiency by reducing cycling losses due to less mass of refrigerant to be redistributed 

and to achieve thermal equilibrium. Conversely, the main disadvantage of reducing charge size is that 

the performance of systems tends to be more sensitive to leakage, i.e., efficiency and capacity can degrade 

sooner as refrigerant is leaked out. Sometimes the stability of the system can be reduced, for example, 

when controlling evaporator superheat. It is important to carry out charge reduction commensurate with 

system performance optimisation, such that dual benefits are obtained, and one isn’t achieved at detriment of the other.

Until recently, the approach of charge size reduction was not normally carried out in RAC industries, 

since there was no motivation to do it. This is a fairly new concept, and it is likely to become more of a 

focus as environmental and safety issues progress.25 

5.4.2 General approach

The general approach to reducing the refrigerant charge can be addressed through three levels:

• Considering the application; that is external considerations that, for example, reduce heat load on the 

system or shorten pipe lengths

• Considering the system architecture; that is the system type, for example, the use of a direct expansion 

instead of a flooded system or an indirect system instead of a direct expansion system

• Considering the system component; that is the selection and design of, for example, heat exchangers, 

pipework and so on

For air conditioning systems, reduction of heat load is difficult to address, as this is often an independent 

issue. However, for refrigeration equipment, issues such as insulation thickness, electrical component 

efficiency and other such design aspects should be considered. In terms of system architecture, there are 

a variety of implications that may be relevant to the system charge size: whether it is direct, flooded or 

indirect system; single or multi-evaporator; single-stage, multi-stage or cascade system; integral or split 

type system. Depending upon the type and purpose of the system, other concepts should be considered. 

For example, to adopt an indirect system instead of a direct expansion or flooded type system can reduce 

the charge size by up to a factor of 10, whilst in some cases the use of an indirect circuit may not be 

practical, it may introduce significant additional costs or it may result in a reduction in system efficiency.

A common way of assessing the refrigerant charge within a system is through the “specific charge”, 

which is the ratio of charged mass to the nominal cooling capacity. Generally, the specific charge – for a 

particular system design – varies according to nominal cooling capacity, and the application temperature 

(Figure 24). For an increase in cooling capacity the specific charge will lessen, due to the disproportionate change in internal volume for refrigerant-containing parts. For a given system (with a fixed charge), a 

lower evaporating temperature will coincide with a reduction in cooling capacity, thus the specific charge 

will be greater. In addition, systems that rely on longer pipe runs and that employ receivers will also have 

higher specific charges. 

25 The reader is directed towards publications under the International Institute of Refrigeration, where several technical conferences 

specifically address the theme of minimisation of refrigerant charge (www.iifiir.org)
124

Figure 24: Illustration of how specific refrigerant charge may vary according to system cooling capacity 

and application temperature range

Figure 25 provides some data for split type air conditioners, using R22. This data set represents around 

250 models from nine different manufacturers. It can be seen that for a given cooling capacity, some 

models use over three times as much refrigerant as some others. This example is useful for highlighting 

the potential for charge size reduction in such equipment.

Figure 25: Variation in specific refrigerant charge for approximately 250 split air conditioners using R22, 

from nine different manufacturers

5.4.3 Consideration of individual components

It is useful to understand the typical distribution of refrigerant within systems, as it helps to identify the 

areas where charge minimisation work should be focussed. Figures 3 show a breakdown of refrigerant 

distribution amongst components for a split type air conditioner, although this is similar to, for example, 

window air conditioner, a small air conditioning chiller, commercial integral display cabinet and a 

commercial freezer cabinet. In general, it can be seen that the majority of the refrigerant is held within 

the condenser, compressor, evaporator and liquid line. In terms of component design the greatest potential for charge reduction is within the heat exchangers, and this should be the main focus.

151

application temperature (Figure 24). For an increase in cooling capacity the specific charge will 

lessen, due to the disproportionate change in internal volume for refrigerant-containing parts. For a 

given system (with a fixed charge), a lower evaporating temperature will coincide with a reduction 

in cooling capacity, thus the specific charge will be greater. In addition, systems that rely on longer 

pipe runs and that employ receivers will also have higher specific charges. 

Figure 24: Illustration of how specific refrigerant charge may vary according to system cooling 

capacity and application temperature range 

Figure 25 provides some data for split type air conditioners, using R22. This data set represents 

around 250 models from nine different manufacturers. It can be seen that for a given cooling 

capacity, some models use over three times as much refrigerant as some others. This example is 

useful for highlighting the potential for charge size reduction in such equipment. 

0,0 

0,2 

0,4 

0,6 

0,8 

1,0 

0 5 10 15 20 

Specific charge (kg/kW) . 

Nominal capacity (kW) 

Specific charge (kg/kW)

Nominal capacity (kW)

0 5 10 15 20

1,0

0,8

0,6

0,4

0,2

0.0
125

Figure 26: Example distribution for refrigerant charge within a split air-conditioner

In carrying out the charge minimisation work, certain criteria should be adhered to: in particular, 

maintain the design cooling (or heating) capacity, and maintaining – or exceeding – the existing efficiency. Furthermore, it is important to consider the effect of charge variation on both cooling (or 

heating) capacity and system efficiency. This is a particular concern when dealing with systems that use 

capillary tubes, short-tube restrictors, and to a lesser extent, thermostatic expansion valves. 

Compressors

Different types of compressors have a range of internal volumes, thus the quantity of refrigerant contained within the compressor will vary widely accordingly. For example, rotary, scroll and hermetic 

reciprocating types often have smaller internal volumes than, say open and semi-hermetic reciprocating 

and screw compressors. Typically, the refrigerant mainly occupies two regions within a compressor, being 

in low pressure vapour within the suction chamber and absorbed in the oil within the sump. Thus, in 

order to reduce refrigerant charge within the compressor, three options exist:

• Select a compressor with as small an internal volume as possible

• Reduce the in internal volume of the suction chamber

• Use a oil with low refrigerant solubility

In terms of selecting a compressor with a small internal volume, data can normally be supplied by 

compressor manufacturers. Reducing the internal volume of the compressor is obviously an activity for 

the compressor manufacturer rather than system designer. It should also be noted that if the internal 

volume is very small, there can be high pressure losses along the compressor flow path which would 

therefore be detrimental to performance, and may also negatively affect oil distribution within the 

crankcase. The oil can be a significant sink for refrigerant, so using an oil with a low solubility (with the 

refrigerant used) will absorb minimal quantities of refrigerant during operation. In particular, many 

mineral oils and polyol ester (POE) oils tend to hold more refrigerant than polyalkyl glycol (PAG) oils. 

Alkyl benzene (AB) and polyalpha olefins (PAO) oils have moderate solubilities. However, several oil 

producers provide lubricants optimised for HCs, which tend to have lower solubility. Ultimately, the 

choice of oil is typically more strongly dependent upon performance criteria, rather than for the purpose 

of charge reduction, and it is usually the choice of the compressor manufacturer as to which lubricant is 

used within a specific compressor.

Evaporators and condensers

The choice of evaporator type and condenser has a major influence on the contained mass of refrigerant. 

Whilst the choice of exchanger type is limited because of the application (i.e., refrigerant-to-water, 

refrigerant-to-air, etc) it is still possible to address sub-types of heat exchanger and specific designs. 

evaporator 

condenser 

compressor 

discharge liquid suction 
126

In the case of refrigerant-to-air heat exchangers, there is a choice of finned-tube type exchangers or 

micro-channel exchangers (where the small bore tubes are essentially within the fins). The latter can be 

more costly, although their use can dramatically reduce the charge, and also the total volume for the 

exchanger (for the same capacity and temperature difference) can be notably smaller. Halving the pipe 

diameter but doubling the length (to maintain surface area) will approximately halve the charge, thus, in 

general, a higher mass velocity will result in lower charge. 

Conventional finned-tube coils can therefore be redesigned by reducing pipe diameter and increasing the 

number of circuits. Since the viscosity of HCs tends to be lower than that of the common HCFCs and 

HFCs, an incremental drop in the pipe diameter will often result in the same pressure loss; further 

reduction in diameter normally necessitate an increase in the number of circuits. Typically for the 

evaporator, only a moderate reduction in charge size may be achieved. However, adjusting the condenser 

design in this way can provide significant reductions in charge. 

An illustration of such an approach is provided in Figure 27. Initially, the condensing heat transfer 

coefficient for R22 and R290 is shown for the same condenser coil (a). However, when comparing the 

pressure drop (b), it is seen that R290 is much lower. Therefore the pipe diameter of the pressure drop of 

the R290 coil matches that of the original R22 coil (c). Finally, comparing the subsequent heat transfer 

(d), it is seen that the value for R290 is about double that of R22. However, key benefit is that the 

refrigerant volume of the condenser has been halved and correspondingly the refrigerant mass. 

Figure 27: Illustration of effect of advantageous reduction of tube diameter for R290 condenser

It is also appropriate to design the circuitry of the condenser so that the entire subcooling region is 

included within a single tube, to further enhance heat transfer in this single-phase region. Also with 

finned tubes, if it is possible the outside surface area should be increased, e.g., by more fins per unit 

length, as this allows for a smaller internal volume (or tube length), thus reducing charge. However, as 

with many other aspects, other factors pose limitations as to how closely fins can be spaced (for example, 

avoidance of excessive frosting or avoiding accumulation of debris within dusty environments).
127

A number of potential problems exist with lower charge finned tube and micro-channel exchangers, and 

it is worthwhile paying particular attention to these aspects:

• With micro-channels, the shorter circuits tend to inhibit condensate drainage, especially with single 

pass exchangers with common headers

• Frosting and defrosting is major problem because of the close proximity of the fins and tubes

• A large portion of the refrigerant can exist within the bends, tees and manifolds, thus a significant 

reduction in pipe diameter may not be as pronounced in the charge reduction of the overall heat 

exchanger

• The likelihood of internal fouling and mal-distribution of refrigerant are greater, similarly, problems 

with icing of moisture can also occur in evaporators

• When carrying out studies, and in particular modelling exercises to investigate the possibilities of 

smaller tubes, it is important to recognise that the pressure drop and heat transfer correlations usually 

employed for normal sized tube diameters, may not be applicable to very small tubes so more appropriate ones should be sought as well as experimental validation

• Within evaporators, there is a greater occurrence of boiling instability with smaller diameter tubes, 

resulting in intermittent variations in heat transfer coefficient, thus necessitating a larger than expected 

internal surface area to account for this phenomenon

For refrigerant-to-water heat exchangers, there is again a choice of different types: shell-and-tube, 

tube-and-shell, coaxial tube and plate heat exchanger types. Generally shell-and-tube exchangers (which 

have the refrigerant on the outside of the tubes) require very large quantities of refrigerant and are 

normally used for specific types of large systems. Tube-and-shell (where the refrigerant is inside the 

tubes) require smaller quantities of refrigerant. Wherever possible, it is preferable to employ plate type 

evaporators and condensers since these contain relatively small quantities of refrigerant, and in addition 

tend to be much lower cost. Different manufacturers offer plate exchangers of various designs, some of 

which require less charge than others. It is advisable to carry out a comparison of different products to 

identify the lower charge based on a given capacity.

It is also worthwhile considering the use of internally treated surfaces (such as the use of roughened 

surfaces, geometric enhancements, turbulators, etc) as these may also enable smaller tube bores whilst 

maintaining the desired heat transfer coefficients.

Lastly, it is always important to consider the implications of using “bought” heat exchangers and specially designed heat exchangers. Generally, a heat exchanger supplier may only be able to provide a 

limited number of designs, for example, in terms of the number of different pipe diameters, tube spacing, etc. This obviously limits the potential opportunities. However, if a company can offer to build any 

design required, this offers a greater scope for charge size reduction and associated optimisation. 

Liquid, delivery, suction and discharge lines

The refrigerant mass contained within interconnecting pipework can vary widely between systems due 

to particular geometry and system layouts. It is reported that well selected piping can reduce charge by 

15 – 40%, depending upon the particular system design. When using HC refrigerants, there are particular advantages compared to many other fluorinated refrigerants, such as R22, since the viscosity of HCs 

is lower. Thus for the same sized pipe, smaller pressure drops occur. This can be exploited by employing 

slightly smaller pipe diameters, which if done correctly, will reduce charge mass whilst not adversely 

affecting performance. Consideration of the liquid line can offer particular advantages. Since the 

volumetric flow within the liquid line is small (compared to vapour phase piping), smaller diameters can 

be used to significantly reduce the refrigerant mass. However, it is important that pressure drops are not 

allowed to increase too much, otherwise “flashing” of the liquid refrigerant can occur which is detrimental to system operation particularly in fittings. However, such problems can be overcome through the use 

of liquid pumps (usually applied to larger systems) or liquid-suction heat exchangers. If the system 
128

employs a reasonably long (two-phase) delivery line into the evaporator, similar benefits can be obtained 

with smaller diameters. In fact, it is possible to adopt this concept for liquid lines, i.e., to use “pre-expansion” where liquid exiting condenser is slightly expended, so that both liquid and vapour pass through 

liquid line, so that the vapour displaces what would normally be occupied by liquid. Lastly, it should be 

noted that – particularly for smaller systems – the course increments of standard refrigeration piping 

may not necessarily allow reductions in pipe sizes without increasing overall pressure drop. 

Liquid receivers and suction accumulators

Liquid receivers may be located on the high pressure side, low pressure side or at intermediate pressure in 

a multi-stage system. They usually demand high additional quantities of refrigerant (often almost 

doubling the refrigerant charge), and therefore they can be avoided if possible. However, they are 

normally used for a specific reason, for example, where maintaining efficiency over a wide range of 

operating conditions or for pump-down cycles, in which case their use may be difficult to neglect. 

Alternatively a carefully designed larger condenser may be used as an alterative to the receiver, so that 

greater refrigerant charge can be avoided. If the receiver is absolutely necessary, it should be sized so that 

it can accommodate as necessary the maximum and minimum variation in liquid level, only. Furthermore, it is preferable to use vertically mounted (instead of horizontal) as these can be more precisely 

sized to accommodate the tolerances. 

Suction accumulators are also generally used when a wide range of operating conditions is anticipated 

and capillary tube or short-tube restrictor is used in the system, to avoid liquid flooding to compressor. 

Although the accumulators may be fairly voluminous, because they contain superheated vapour the 

occupied charge mass is not as significant as a liquid receiver. However, notable reductions in charge size 

can be obtained by optimising the accumulator geometry; that is as small a volume as possible, whilst 

reducing velocity sufficiently to deposit liquid droplets.

5.5 SOURCES OF IGNITION AND METHODS OF AVOIDING IGNITION 

5.5.1 Introduction

If refrigerant leaks from the system, there must be no potential sources of ignition (SOI) associated with 

the equipment that could ignite it. Potential SOI include:26

• A spark with energy > 20 mJ

• An open flame

• A hot surface > 450°C

Therefore precautions should be taken to avoid the possibility of direct sources of ignition such as 

excessively hot surfaces, electrical switches and exposed electrical contacts or coming into contact with 

any release of refrigerant within the system. This may be addressed in a number of different ways.

5.5.2 Hot surfaces

All parts of the equipment should be checked to ensure that the temperatures of any surfaces that may 

be exposed to leaked refrigerant do not exceed the auto-ignition temperature of the refrigerant, reduced 

by 100 K (see Table 24 in Appendix 4); this equates to about 350°C for most HCs. Unless the maximum surface temperature of a device (under uncontrolled conditions) is stated by the manufacturer, the 

temperature should be checked by testing. Such tests are specified in EN 60335-1, EN 60335-2-24, EN 

60335-2-34, EN 60335-2-40, EN 60335-2-89 and EN 60204-1. In all of these standards, the tests 

follow the criteria:

26 A more extensive list of potential SOI to consider are: flames, hot gases, hot particles; mechanically generated sparks; electrical 

apparatus (electric circuits are opened and closed, loose connections, stray currents); static electricity; lightning; radio 

frequency electromagnetic waves (from 104 Hz to 3 x 1012 Hz); other Electromagnetic waves (from 3 x 1011 Hz to 3 x 1015 Hz); 

ionizing radiation; ultrasonics; adiabatic compression, shock waves; exothermic reactions, including self-ignition of dusts
129

• Temperature is measured continuously by thermocouples fixed on the exposed surface of the device

• Protective devices other than self-resetting thermal motor-protectors for motor-compressors must not 

operate, except those which are terminated by a non-self resetting protective device or by an intentionally weak part becoming permanently open-circuited

• When steady conditions are established, thermal motor protectors for motor-compressors must not 

operate

• If a control device is used which stops the defrosting at a given temperature or pressure, the defrosting 

period is automatically terminated when the control operates

• During the test sealing compound must not flow out

5.5.3 Electrical sources of ignition

Electrical components should be selected and/or positioned carefully. The RAC equipment must be 

constructed so that any leaked refrigerant will not flow or stagnate where electrical components, which 

could be a source of ignition (and which could function under normal conditions or in the event of a 

leak) are fitted. According to the relevant safety standards (EN 378, EN 60335-2-24, EN 60335-2-40, 

EN 60335-2-89) all electrical components that could act as a source of ignition under these conditions 

must comply with one of the following:27 

• The component is constructed according to EN 60079-15 or IEC 60079-15 (for group IIA gases) 

complying to clauses 9 to 26 

• The component is constructed according to EN 60079-15 or IEC 60079-15 (for group IIA gases) 

complying to 

- clauses 3 and 4

- clauses 17 to 30 

- clause 31 for restricted dressing enclosures 

- clause 33.5.3.2 (here the test may also be used for enclosures larger than 100 cm3

)

• The component is located in an enclosure which complies with the requirements of EN 60079-15 for 

enclosures (suitable for use with group IIA gases)

• Any electrical components suitable for use in zone 2, 1 or 0 area as defined by IEC 60079-14

• The component is not located in an area where a potentially flammable mixture of refrigerant and air 

could accumulate; this is demonstrated by the leak simulation test described later

In addition, care should be taken to ensure that electrical terminals, including capacitor terminals are 

adequately tightened and secured against loosening and that adequate insulation is provided to avoid live 

parts shorting together. Similarly, electric motors must be of brushless design.

Whilst it is standard practice to earth all parts of an assembly (including housing and ancillary parts), it 

is critical to ensure that this is carried out comprehensively for equipment using flammable refrigerants.

5.5.4 Fan assemblies

For the case of fan assemblies, it may be possible for sparks to be created between the fan blades and the 

housing. Whilst the likelihood of sparks occurring is unlikely, it is ultimately the responsibility of the 

system designer to consider this issue. In general, the possibility of sparking due to mechanical impact is 

essentially negated provided that certain materials are avoided, and further the likelihood of impact is 

reduced by ensuring a minimum clearance distance between the parts. For general guidance, the following should be followed:

• The fan construction must be of rigid design, considering casings, supporting structures, guards, 

protective devices and other external parts, particularly if the deformation resulting from an impact is 

such that the moving parts do not come into contact with the casing

27 Refer to the specific standard for precise details
130

• Consideration should be given to the pairing of materials for the casing and fan blades, which if come 

into contact during operation may result in heat generated from friction or sparks arising from impact; 

in general

- plastic materials for both pair is normally acceptable

- plastic materials and any metal pair is normally acceptable

- aluminium and aluminium or other metallic pairs are normally acceptable

- stainless steel pairs must not be used 

- steel alloy and brass pairs must not be used

• If (non-aluminium) metallic pairs are used, chrome content should be less than 15% (to avoid sparking), rotational speed should be less than 40 m/s, and additional considerations are necessary is the 

shaft power is greater than 5.5 kW

• Paint containing aluminium or iron oxides must not be used because of the risk of sparks

• The fan must be fitted so as to avoid excessive vibration

• All metallic parts must be earthed

• The most important criterion is the clearance distance between the fan blades and the casing, which 

shall be at least 1% of the diameter and no less than 2 mm

When selecting a fan, its purpose should also be considered, and the level of protection chosen accordingly. For example, if the fan is used solely for circulating air, then the level of protection may not 

necessarily be very high, whereas if the purpose of the fan is specifically to exhaust a flammable concentration arising from a release of refrigerant, then the requirements must be appropriate for and meet the 

rules for use in hazardous atmospheres. 

EXAMPLES OF POTENTIAL SOURCES OF IGNITION

The following electrical items should receive particular attention since they may provide 

direct electrical sources of ignition:

Providing such items only comprise solid state parts or have casings which are solid encapsulated or otherwise sealed to at least IP67 or are located externally to the casing of the 

refrigerant containing parts then the criteria of the test below are normally achieved.

• manual switches

• liquid level switch

• condensate pump

• thermostats

• flow switches

• fan speed controllers

• pressure switches

• start relays 

• programmable controllers

• potential relays

• defrost switches

• contactors, isolator switches

• universal relays

• time switches

• mini-circuit breakers

• oil differential switches

• thermal overloads

• fan delay switches
131

5.5.5 Further considerations

Depending upon the approach used for avoiding sources of ignition, its integrity over the lifetime of the 

equipment must be considered. In particular:

• Sealed or enclosed components. A damaged component could be replaced by one of insufficient 

tightness, or after repairing a component in-place, the method of sealing may accidentally be spoiled. 

In addition, general wearing of a component, such as through weathering or corrosion may also render 

it unsafe according to the requirements of safety standards.

• Solid state components. Whilst such devices do not normally produce sparks, in the event of overloading or manufacturing defects, excessive temperatures may occur, arcing or even a naked flame.

• Specially positioned components. Employing the approach that uses testing to identify the positioning 

of potential sources of ignition in locations that will not experience flammable concentrations in the 

event of leakage are advisable since it avoids the potential complications highlighted above. However, it 

is important, firstly to ensure that the tests are conducted and analysed thoroughly since it is easy to 

make errors whilst carrying out this approach, and secondly that it is not possible for the same or 

similar component to be repositioned (to a more vulnerable location). 

• Components inside confined spaces. Whilst certain safety standards permit the use of potential SOI 

inside confined spaces – such as refrigerated cabinets or chiller housing – provided that certain criteria 

are met, it is strongly recommended that this approach is avoided. Even if a number of features are put 

in place, and tests carried out, to prevent the refrigerant from entering a confined space and reaching a 

potential SOI, the consequence of ignition in such a location are much more severe than ignition 

occurring outside a confined space (see Part 5.8.7). Given the effects of ageing of components or the 

possibility of untrained technicians making unexpected modifications to equipment, it is highly 

advisable to eliminate all potential SOI from enclosed or confined spaces. 

In addition to the above, it is also worth evaluating the potential for parts that are not normally considered, to be sources of ignition under failure scenarios. This may include electrical connections and 

terminals that may work loose and re-wirable fuses.

Whilst plugs and sockets for connecting equipment to mains supply may not necessarily be SOIs, there 

is a potential for them to be, especially if they are inadvertently separated. Whilst for smaller systems 

that have a relatively small charge size, this issue may not be of concern, for systems that use larger 

charge sizes and that may be serviced on site, it can be worth considering having the plus and sockets to 

conform to the following:

• Interlocked mechanically or electrically, or otherwise designed so that they cannot be separated when 

the contacts are energized and the contacts cannot be energized when plug and socket are separated. 

• If they are allocated and connected to only one apparatus, they can be secured mechanically to prevent 

unintentional separation and the apparatus shall be marked with the warning – “WARNING – do not 

remove or replace fuse when energised”, or “WARNING – do not separate when energised”

Similarly, plugs and sockets and similar connectors for internal connections require a minimum separating force of (at least 15 N) or they are prevented by mechanical means from loosening or separating. 

It is also worth remarking on the presence of electrical arcs inside the refrigerating machine, particularly 

the compressor: it is known that for hermetic and semi-hermetic compressors, arcing will at times occur, 

however, the concentration of the refrigerant is (or should be) 100%, i.e., absent of air, or oxygen. 

Therefore, any arcing inside the system will not result in combustion. It should be noted that even in the 

event that there is an inward leak at the suction side of the compressor due to a sub-atmospheric evaporating pressure, a normal system will be unable to operate with even 5% air, let alone 90% (as would be 

required for ignition). 
132

5.5.6 Leak simulation tests for potential sources of ignition

When HC refrigerants are employed, it may be necessary to carry out a test to determine whether 

electrical components are a potential source of ignition, which is applied to one sample of each refrigeration system. This type of test is described in most of the relevant standards, although there are some 

variations, depending upon what type of equipment the standard covers. The tests included in EN 378, 

EN 60335-2-24, EN 60335-2-40 and EN 60335-2-89 are detailed below. There is some deviation 

between the tests detailed in some of the standards, partly due to the characteristics of the equipment, 

and partly due to the disconnectedness in drafting the requirements. The general methodology is provided that applies to all tests, and the variations according to equipment type are identified within the Table 

11. In general, there are two categories of equipment: refrigeration equipment for storage (e.g., domestic 

and commercial refrigerators, freezer, etc), and all other equipment. Although the test requirements for 

the former come from the standards that apply to domestic and commercial refrigeration appliances 

using up to 150 g of HC refrigerant, the test methods, from say EN 378 that apply to all other equipment, are not as suitable for refrigeration equipment for storage that uses larger charge sizes. 

However, these tests are also sensitive to the design of the equipment (at the time of testing) and of 

course to the approach taken by those carrying out the work. Therefore, additional options are also 

provided below which will enable a more robust series of tests to be carried out. 

EXAMPLE OF LEAK SIMULATION TEST

The figure below shows the results of a leak simulation test on a thermostat enclosure within 

a refrigerated compartment. The method was as described in this Part: From an electronic 

balance-mounted cylinder within a water bath at 32°C, the R600a was injected at a “critical 

points” into the cabinet in the foamed area via a capillary tube. Sampling points connected to 

an infra-red gas analyser were positioned within the thermostat enclosure and another in the 

middle of the fridge compartment. 30 grams (being 80% of the nominal charge) of R600a was 

injected at each critical joint. According to the conditions, the release time was approximately 

seven minutes. During the first test from the first “critical point”, a negligible amount of gas 

entered the compartment (data not shown as concentration <0.1% of LFL). The second test 

from the second “critical point” showed that there was a notable rise in gas concentration. 

However, it can be seen there is a delay between the time of the release and the build up of 

the gas – this is due to the gradual migration of the refrigerant through the foam within the 

wall of the cabinet. However, 

neither the concentration 

within the compartment, nor 

importantly, the concentration 

within the enclosure approached any of the minimum 

concentrations within the 

test criteria (i.e., 40%, 50% or 

75% of the LFL). Thus, in this 

example, the thermostat 

enclosure is considered not be 

a potential source of ignition. 

EXAMPLE OF LEAK SIMULATION TEST 

The figure below shows the results of a leak simulation test on a thermostat enclosure within a refriger

compartment. The method was as described in this Part: From an electronic balance-mounted cylinde

a water bath at 32°C, the R600a was injected at a “critical points” into the cabinet in the foamed area v

capillary tube. Sampling points connected to an infra-red gas analyser were positioned within the therm

enclosure and another in the middle of the fridge compartment. 30 grams (being 80% of the nominal c

of R600a was injected at each critical joint. According to the conditions, the release time was approxim

seven minutes. During the first test from the first “critical point”, a negligible amount of gas entered the 

compartment (data not shown as concentration <0.1% of LFL). The second test from the second “critic

point” showed that there was a notable rise in gas concentration. However, it can be seen there is a de

between the time of the release and the build up of the gas – this is due to the gradual migration of the 

refrigerant through the foam within the wall of the cabinet. However, neither the concentration within th

compartment, nor importantly, the concentration within the enclosure approached any of the minimum 

concentrations within the test criteria (i.e., 40%, 50% or 75% of the LFL). Thus, in this example, the 

thermostat enclosure is considered not be a potential source of ignition. 

0%

20%

40%

60%

80%

100%

0 20 40 60 80

Time from start of release (mins)

% of LFL

inside fridge compartment

inside thermostat enclosure

40% of LFL

50% of LFL

80% of LFL

5.5.6 Leak simulation tests for potential sources of ignition 

When HC refrigerants are employed, it may be necessary to carry out a test to determine wh

electrical components are a potential source of ignition, which is applied to one sample of ea

refrigeration system. This type of test of described in most of the relevant standards, althoug

there are some variations, depending upon what type of equipment the standard covers. The 

included in EN 378, EN 60335-2-24, EN 60335-2-40 and EN 60335-2-89 are detailed below. 

is some deviation between the tests detailed in some of the standards, partly due to the 

characteristics of the equipment, and partly due to the disconnectedness in drafting the 
133

When carrying out these tests, the test area should be constructed according to the requirements of, for 

example, the EU ATEX Directive and/or the requirements indicated by hazardous area standards, such 

as the IEC 60079 series. The installation should be approved by a competent body.

General test methodology

A refrigerant leak is simulated at a number of positions around the circuit that are considered to be 

“critical”, i.e., points that a leakage is most probable, as discussed below. Throughout the test, the 

concentration of refrigerant is measured continuously at positions surrounding each potential source of 

ignition. The concentration of leaked refrigerant is measured at least every 30 s from the beginning of 

the test until completion, as close as possible to electrical components which, during normal operation or 

abnormal operation, produce sparks or arcs. 

The existing protection – in whatever form – is considered to provide an acceptable level of resistance to 

the ingress of flammable refrigerant if the measurements demonstrate the following criteria are met:

• The concentration does not exceed 75% of the refrigerant LFL at any time28 

• The concentration does not exceed 50% of the refrigerant LFL for more than 5 minutes, or the 

duration of the test if less than 5 minutes during and after the release quantity has been injected

• The measured refrigerant concentration surrounding a component that will not function during the 

pre-purge period may exceed the 75% of the LFL during this time29 

The test is performed twice and is repeated a third time if one of the first tests gives more than 40% of 

the LFL.

28 It is recommended that 50% of the LFL is used throughout (instead of 75% specified within the standard) in order to be 

consistent with the requirements of EN/IEC 60079-15 

29 It is also recommended that 50% of the LFL also be used here

PAY ATTENTION TO REFRIGERATED COMPARTMENTS

It is of highest importance to consider the use of electrical items 

and other potential sources of ignition within refrigerated compartments. This is because, if there is a leak into the compartment, it 

is very difficult for it to be dispersed, unlike if the leak is to the 

outside of the appliance where the refrigerant will normally disperse quickly. If refrigerant finds its way into the compartment it is 

likely to form a flammable concentration that could last for hours, 

days, or even weeks, and in the event of a failure of an electrical 

component, then the consequences can be severe. Therefore, follow 

certain rules:

• If at all possible, make sure no potential sources of ignition, even 

if they are protected, are not located within the compartment

• Make sure there is absolutely no way that refrigerant can migrate from the position of a 

leak hole in the refrigerant-containing parts, through the insulation, along the outside or 

within electrical cables, through “sealed” panels, and so on; carry out thorough testing to 

address all eventualities.

• Make sure that any form of sealing (for example, around cable entries, etc) is extremely 

reliable, such that it cannot be removed, it will not dissolve, carbonise or degrade in any 

other way over time; consider the extended lifetime of the equipment, i.e., 20 years or 

more.
134

The generally applicable conditions for the release are as follows:

• A critical point may be, but not limited to:

- a joint in the refrigerant system tubing

- a bend of more than 90°

- some other position in the circuit that is considered to be weak due to the thickness of the metal,

- exposure to damage, sharpness of a bend or the manufacturing process

- aluminium to copper joints or other bi-metallic connections

- gaskets or seals of compressors, valves or other components

• The release is made in vapour phase, injected through a suitable capillary tube, and care should be 

taken to ensure that the installation of the capillary tube does not notably influence the test results, for 

example, by foam or other substances entering the capillary tube

• The mass flow rate through the capillary tube is dependent upon the type of equipment being tested 

and that particular part under consideration

• During a test in which the appliance is operated, gas injection is started at the same time as the 

appliance is first switched on

• The release rate should be controlled and the released mass confirmed by measurement (preferably by 

weighing the cylinder); ensure that there is liquid remaining in the cylinder upon completion of the test

• Whenever tests are carried out with the equipment running under normal operation, this is done at the 

rated voltage

• The location must be draught-free, unless the draft is produced by the appliance

• The positioning of the refrigerating system and the refrigerant sampling equipment must not notably 

influence the test results

• If a blend refrigerant is used that can fractionate, the test results are evaluated considering the blend 

component that has the lowest LFL

• The equipment for measuring the refrigerant concentration should have a sufficiently rapid response to 

changes in concentration, typically 2 to 3 seconds

• If the measuring method is one that removes gas samples, then it must do so at a rate less than 4 ml 

per minute

Particular test conditions apply according to the type of equipment under consideration, as detailed 

Table 11. For equipment that has potential SOI both within an enclosed space and outside or on the 

shell of the equipment or in positions some distance from refrigerant containing parts, two or more sets 

of tests will need to be conducted depending upon each individual situation. 

For refrigerated storage equipment, there are two categories: those with protected cooling systems and 

those with unprotected cooling systems. 

Appliances with a protected cooling system are those:

• Without any part of the cooling system inside a food storage compartment

• Where any part of the cooling system which is located inside a storage compartment is constructed so 

that the refrigerant is contained within an enclosure with at least two layers of metallic materials 

separating the refrigerant from the storage compartment, each layer having a thickness of at least 0.1 

mm, the enclosure has no joints other than the bonded seams of the evaporator where the bonded 

seam has a width of at least 6 mm

• Where any part of the cooling system which is located inside a storage compartment has the refrigerant contained in an enclosure which itself is contained within a separate protective enclosure, if 

leakage from the containing enclosure occurs, the leaked refrigerant is contained within the protective 

enclosure and the appliance will not function as in normal use

• The protective enclosure must also withstand a scratch test (as described in the relevant standards)
135

Appliances with an unprotected cooling system are those:

• Where at least one part of the cooling system is placed inside a food storage compartment or those 

which do not comply with the requirements for protected cooling systems

Equipment may also be designed to employ a pre-purge system, where a fan is used to purge a particular 

space where potential SOIs may be present, but before they are energised. If such an approach is employed, then the design of the circuits must be fail-safe, that is, if the airflow cannot be proved, then the 

electrical circuit cannot be energised.

AWARENESS OF OWNERS AND OPERATORS

Depending upon the type and number of systems being installed, as well as the local circumstances, it may be necessary for the equipment owners and operators to be fully aware of the 

use of flammable refrigerants (for example, building and facilities managers). Sometimes the 

installation is such that additional work may be carried out that is somehow linked to or impacts on the refrigerating or air conditioning system that could compromise the intended level 

of safety. This particularly applies to situations where other parties unrelated to the cooling 

equipment are required to do work that necessitate tampering with the existing installation. If 

these contractors are unaware of the presence or implications of flammable refrigerants, then 

subsequent hazardous situations may arise. Therefore owners and operators need to be aware of 

any work that is to be carried out that falls into this category, and enlist assistance and advice 

from the relevant personnel who are competent with regard to the cooling systems. Situations 

that may pose a risk primarily include installation or modification to electrical equipment and 

electrical supplies that are linked to, or even located nearby, the refrigeration system, but even 

structural modifications to buildings, housings, etc. It is essential that where systems currently 

conform to safety requirements, the activities of other parties do not result in non-compliance. 
136Table 11: Overview of the various test requirements for different types of equipment Table 1: Overview of the various test requirements for different types of equipment 

Refrigerated/freezer cabinets

Criterion

Protected cooling system Unprotected cooling system

All other systems

Leak quantity 50% of the charge ±1.5 gÆ For componentsinside space

80% of the nominal refrigerant charge ± 1.5 g or the maximum

that can be injected in 1 hour, whichever is the smaller

80% of the nominal charge of the refrigerant ± 1.5 g

Total release amount is total

nominal charge or the maximum

quantity that leaks based on testing

Leak rate Constant rate over one hourÆ For componentsinside space

According to the release amount made through a capillary tube of

diameter 0.7 mm ± 0.05 mm and a length of between 2 m and 3 m

Total release amount in time not exceeding 10 minutes

Air conditioners, heat pumps, etc (up

to 5 kg): Total release amount ±5%

in four minutes

Other systems: The total release

amount at 0.0017 kg/s (100 g/min)

per 1 m3 of internal volume of the

equipment enclosure

Location of release At the point of closest approach of critical points in the external parts of the cooling circuitÆ For componentsinside space

In the most unfavourable direction Close as possible to the centre of the back wall of compartment,

one‐third of the height down

In the most unfavourable direction

Operating mode Appliance switched off or operated under normal operation, whichever gives the least favourable resultÆFor componentsinside space

Appliance is tested with doors and lids closed, and is switched off

or operated under normal operation, whichever gives the more

unfavourable result. During a test in which the appliance is

operated, gas injection is started at the same time as the appliance

is first switched on.

Two tests are carried out: (a) where 30 minutes after the injection

is completed, the door or lid is opened at a uniform rate in a time

between 2 s and 4 s, to an angle of 90° or to the maximum,

whichever is less; (b) as with (a), except from the start the door or

lid is subjected to an open/ close sequence at uniform rate of

between 2 s and 4 s. For more than one door or lid, the less

favourable sequence or combination of opening lids or doors is

used. If fitted with fan motors the test is performed with the less

favourable combination of motor operation

Appliance switched off or operated

under normal operation, whichever

gives the least favourable result

(unless a pre‐purge is activated prior

to energising any loads, in which

case test is conducted whilst

appliance is operating

Refrigerantcylinder temp

32 °C ± 2 K for leakage simulation on low‐side pressure circuits, or 70 °C ± 2 K for leakage simulation on high‐side pressure circuits 20 – 25°C

Test room size Not specified Volume ≥ 4 × M / LFL, height ≥ 2.2 mDuration of test Until the concentrations start to go downÆFor componentsinside space

At least 1 h after injection of the gas has stopped Until the concentrations start to go down

Not stated (until the concentrations

start to go down)
137

Additional options

The test methods specified within the standards are based on the assumption that the condition of the 

equipment will remain as new, but this is obviously not the case. Activities such as transportation, poor 

quality service and maintenance, unanticipated component failures, unauthorised modification, reinstallation and basic ageing processes can result in a loss of integrity of the original design and construction. Therefore, it is pertinent to increase the severity of the leak simulation tests in order to address 

these unknown possibilities. 

Aspects to consider regarding the refrigerant release include:

• Assume that a leak could occur from any refrigerant-containing part, not only the “critical” points

• Simulate a leak occurring from a wide pipe diameter to represent a catastrophic pipe fracture

• Consider leaks emanating from ends and joins in pipe insulate where the refrigerant may travel to if 

the rupture is originally from an insulated part of the pipework

• Simulate liquid (or two-phase) leaks in addition to vapour leaks as these could also occur from a 

system

• Test release masses greater than that of the nominal charge, to simulate the case of an over-charged 

system, or where there is a release originating from refrigerant transfer hoses connected to a refrigerant 

cylinder

• Identify possible channels, ducts and cable sheathing that the refrigerant could possible pass through

Aspects to consider regarding the test room conditions:

• The rest room should be completely sealed so that the high concentration within the test space is not 

gradually diluted

• If the equipment may be installed inside and the possibility of it being located in a small space, then 

“soak” the entire piece of RAC equipment within a high concentration of refrigerant to simulate 

extreme conditions; this can be done over a long period of time (for at least one hour), both under still 

conditions and with a constant airflow within the room (average airspeed of around 0.2 m/s) to 

encourage ingress into parts of the equipment

• For confined compartments, such as completely or partially enclosed housings, storage spaces, etc, 

totally fill the volume with refrigerant; gaps and small openings can be covered with paper or film to 

simulate a severe situation

• Measure the gas concentration at more frequent intervals, such as at least every 10 s, since under 

turbulent airflow conditions, the gas concentration can vary erratically over very short intervals 

Aspects to consider regarding the potential SOI:

• Measure the concentration of gas surrounding a component enclosure, rather than inside it, to account 

for it accidentally being replaced with a non-sealed enclosure

• Loosen or damage seals, openings or covers of enclosures to simulate the situation where the technician 

has not left the component in its original condition, or it has been subject to aggressive ageing

• Measure the concentration around solid state components in case of faults

• Remove seals around cable entries and grommets 

• Measure concentration around other non-sparking components such as electrical connections and 

terminals that may work loose, or fuses that may blow 

Other options to increase the severity of the test conditions should be sought, and in particular, they 

should be relevant to the particular characteristics of the equipment under consideration.
138

5.6 DESIGN OF SYSTEM INSTALLATION

5.6.1 Introduction

This section specifically addresses technical requirements for installing systems and equipment. It is 

focussed on the design and construction of the equipment, rather than installation practices of technicians. 

The material represents a compilation of the requirements from several different standards, mainly EN 

378, DIS ISO 5149, IEC 60225-2-24, IEC 60225-2-40, and IEC 60225-2-89. However, this only 

represents guidance and provides some explanation. In order to conform to a safety standard, the safety 

standard should be used. However, in absence of requirements within a national standard, the material 

here could be used in addition.

This section covers:

• Installation of systems inside (normally occupied spaces)

• Installations outside (both occupied and unoccupied locations)

• Machinery rooms

• Piping in general (for any location)

• Safety valves

• Gas detection

• Additional system safety concepts

5.6.2 General requirements for installation of systems inside 

The main considerations for systems that are installed inside where non-competent persons may be 

present (i.e., occupancy categories A and B) relate to the size of the refrigerant charge. In particular, it 

must be ensured that the refrigerant charge of the individual circuits of the system do not exceed the 

charge size limits, as described in Part 5.3. The use of these charge size limits assumes that no additional 

requirements are necessary for the occupied spaces. 

Nevertheless, for the installation and siting of equipment, consideration should also be given to the local 

environment, whereby obviously dangerous situations must be avoided. In this way, attention should be 

paid to the routing of pipework, location of exposed refrigerant-containing parts and major potential 

sources of ignition (such as open fires). 

5.6.3 General requirements for installations outside

There are two situations to consider for outdoor installations to ensure against damage to the system and 

in the event of releases, undesirable consequences:

• where the equipment is located in an area accessible by members of the public, and

• where the equipment is located in a restricted area, with access to authorised persons only

In general, the installation should meet the following guidelines:

• All refrigerant-containing and other critical parts of the equipment must be protected from mechanical 

damage

• Equipment housing should be designed and constructed to be robust resistant to weathering and other 

forms of damage
139

• The equipment should be positioned at a certain distance away from items that may be negatively 

affected by a release of refrigerant, although this is done with consideration to the size of the refrigerant charge

• The equipment should be positioned so that there is always good free ventilation around all sides of the 

equipment, and it will not be inhibited by any permanent or temporary blockages

• The area should be free of combustible materials 

• Consideration should be given to the presence of drains, etc, in case escaped refrigerants could pass 

into them

• Consideration should be given to the positioning of the equipment with regards to opening to other 

buildings, duct inlets, vents, etc

In particular, for equipment located in an area accessible by members of the public:

• The charge of individual refrigerant circuits should not exceed the values specified in Part 5.3

• The equipment housing should be designed to prevent or inhibit interference from others, possibly by 

including special access tools, locks or similar approach

• Consideration should be given to the positioning of the equipment with regards to areas where people 

may congregate

In particular, for equipment located in an area accessible only by authorised personnel:

• Access to the area should be controlled by the means of a fence or similar, which is locked

• The fencing or similar should provide good access to workers, and should preferably be at a radius of 

between 2 m to 5 m away from the equipment, depending upon the charge size and the design of the 

equipment

It is appropriate to designate some “safe” distance from refrigeration systems located outside, in order to 

minimise the possibility of flammable concentrations entering human occupied places (for example, 

through windows, ventilation openings, where people may be congregating outdoors, etc). In general, it 

is difficult to predict the maximum distance that a release of gas will remain above its LFL for an 

outdoors situation, particularly with small quantities (for example, below 100 kg)30. One approximation 

is to consider the maximum volume that may result following a catastrophic release of refrigerant. 

However, outside wind speeds tend to be fairly high (compared to indoor environments) even when the 

air seems “still”, so the extent of the flammable mixture should also be adjusted to account for further 

dispersion provided by the surrounding air. 

Using this approach, the minimum “safe” distance, d (m) may be approximated from equation (7), 

according to the situation illustrated in Figure 28. 

 (7)

where M is the refrigerant charge per individual circuit (kg) and henc is the height (m) of the enclosure 

or fence surrounding the system. Note that the distance of the fence from the unit is not particularly 

relevant (provided it is within the “safe” distance), and in the case that no fencing is present, the height 

of the unit housing may be used for the calculation. The constant CW is a function of the local airflow 

conditions. For example, if the equipment is located in an area which is fairly sheltered, such as besides 

or between buildings, CW ≈ 0.5, whereas if the system is located in an exposed location, such as on a 

roof, CW ≈ 0.25. However, it is always necessary to assess the specific situation on a case-by-case basis.

30 Whilst gas dispersion models are widely available to study such situations, they are predominantly applicable to industrial-scale 

releases, and cannot be used for the situation under consideration here.
140

Figure 28: Indication of the “safe” distance from a refrigeration system 

In addition, especially for equipment with large refrigerant charge sizes (say, above 25 kg per circuit), 

national regulations for the storage of flammable gases should be considered. 

5.6.4 Machinery rooms

For systems, or parts of systems that are located within machinery rooms, certain rules apply. In general 

the machinery room must be located in accordance with local and national regulations, and must also 

conform to the general requirements of safety standards that apply to machinery rooms using any type 

of refrigerant. 

When systems using HC refrigerants are located within machinery room, additional requirements must 

be addressed. These largely relate to the fact that a flammable concentration can be present and therefore 

all possible measures must be taken to avoid its ignition. In general:

• Where the risk of explosion may occur because it is possible for the concentration of refrigerant to 

reach the lower flammability limit, the installation should comply with the requirements for hazardous 

areas (for example, Ex-rated components and construction)

• There must be no source of ignition inside the machinery rooms (see Part 5.5)

• Combustion equipment must not be installed in the same machinery room as that containing an HC 

refrigerating system (for example, no boilers, etc) since these are SOIs

• All piping and ducting passing through walls, ceilings and floors must be tightly sealed so that leaked 

refrigerant cannot pass through into other enclosed or occupied areas

• Air intakes for any equipment must not be taken from within the machinery room

• Precautions must be taken so as to prevent leaked refrigerant that is denser than air entering into 

drainage systems

• Voids in the machinery room floor should be avoided, or designed so that heavier than air refrigerant 

could not accumulate in these spaces in the event of a leak

Consider that it may be possible to design the machinery room such that any release of flammable 

refrigerant is detected and a sequence of measures such as alarms, shutting down electrical supplies and 

use of extract ventilation, so as to avoid excessive use of explosion-proof components.

The machinery room should be designed and built specifically with consideration of the use of HC 

refrigerants. In particular:

• There must be direct access (doors) to the outside machinery rooms is the refrigerant charge in the 

equipment could result in a concentration higher than 20% of the LFL
141

• If the door does not open directly to the outside air then it should be through a dedicated vestibule 

equipped with self-closing, tight-fitting doors

• Have as large an open wall area as possible; ideally at least 50% of the area of one of the walls should 

be open, and preferably close to 100%, since this both encourages good dispersion the event of a 

release but also minimises the severity of the consequences in the event of ignition

• The open area may be fencing, grilles, etc, but should not pose any resistance to the free-flow of air

• If there is any less than 25% of the total (four walls plus ceiling) area that is not open, then some 

explosion relief must be provided if it is possible for the concentration of refrigerant to reach the LFL, 

so that if ignition does occur, only a particular part of the construction will fail or lift, and will do so 

in a “controlled” or intended manner, rather than uncontrolled damage to the building

• This explosion relief may be in the form of a frangible wall or roof, which should have very low mass 

and weak fixings, and should require a force of less than around 20 kPa to open

It is important to have open wall spaces in the machinery room for two purposes. First, free airflow to 

the outside will enable the dilution and removal of refrigerant in the event of a leak. Secondly, if a 

flammable concentration does occur, and it is ignited, then a large open area will reduce the possibility 

of a large overpressure developing and thus more likely to avoid severe consequences such as damage to 

people and property. 

The access to the machinery room should be permitted for suitably trained, authorised persons only. 

Thus, the door should be locked and appropriate signage provided (although movement through the exit 

of the room must not be restricted).

Ideally, the area around the machinery room should meet the requirements for installations of equipment outside (see Part 5.6.3).

There must be an audible and visual alarm positioned inside and at least a visual alarm positioned 

outside the machinery room, close to its entrance. The alarm is be used to warn technicians inside the 

machinery room and those who may enter it from the outside. 

In addition, the emergency exhaust ventilation must be used and should meet the following:

• The outlet from the exhaust ventilation must be in accordance with national regulations

• Emergency exhaust ventilation fan must be either (a) with the motor outside the airflow, or (b) rated 

for hazardous areas, since its purpose is to handle flammable atmospheres

• The fan must be located to avoid pressurisation of the exhaust ductwork in the machinery room, that 

is, it should “suck” and not “push”

• Fan motors and fan blades must not cause sparks to occur if it contacts the duct material (see Part 

5.5.4)

• The outlet must not be restricted but means of keeping rubbish, leaves and birds from entering should 

be employed

• The bottom of any rising ductwork open to the outside must have a drain with a trap for rainwater and 

with access for inspection

• Discharge ducting must be positioned so that there is no risk of vented refrigerant entering other 

buildings in the area nearby, or re-entering the machinery room itself

• The exhaust duct discharge is best positioned at as high a position as possible, and pointed in several 

different directions so as to encourage better dispersion of the vented refrigerant

• The exhaust duct suction inlet points should be well positioned so as to ensure that good flow will 

occur over all the refrigerant-containing parts of the system and that no regions for stagnation could 

occur (see Figure 29)

• The inlet ducts or louvers should be balanced to ensure and even flow throughout
142

The ventilation rate is dependent upon the operating scheme, such that:

• If the machinery room contains absolutely no potential sources of ignition according to hazardous area 

standards, then the ventilation rate should be at least the greater of equation (8) and (9)

 (8)

 (9)

 

• If there are potential sources of ignition, which will be terminated in the event of a leak, then the 

ventilation rate must be at least according to equation (10) to ensure that even in the case of a major 

catastrophic leak, the refrigerant concentration within the machinery room should not exceed the LFL

	 	 	 (10)

• Under all circumstances, there should be a background ventilation rate of at least 4 air changes per 

hour available whenever the machinery room is occupied by technicians or other personnel, i.e., on 

constantly or initiated by (fail-safe) sensors

 

Again, where ventilation fans are used to ensure the discharge of a flammable atmosphere, the fan 

assembly should be suitable for hazardous areas. An emergency stop button (or buttons) must be provided in the machinery room (except for emergency mechanical ventilation), the action of which is to 

stop all refrigerating machinery. A remote switch must be provided outside and near to the machinery 

room door for isolating all electrical equipment not protected for use with HC refrigerants and for 

stopping all machinery.

Fire extinguishers are to be installed in accordance with local fire authority requirements and notices 

describing their correct usage be posted.

Figure 29: Suggestion for mechanical ventilation inlets and outlet for a machinery room

175

V V air = 0.003× Rm & (8) 

2/3 V&

air = 0.014×M (9) 

 If there are potential sources of ignition, which will be terminated in the event of a leak, then the 

ventilation rate must be at least according to equation (10) to ensure that even in the case of a 

major catastrophic leak, the refrigerant concentration within the machinery room should not 

exceed the LFL 

air

0.004× = M V

LFL

& (10) 

 Under all circumstances, there should be a background ventilation rate of at least 4 air changes 

per hour available whenever the machinery room is occupied by technicians or other 

personnel, i.e., on constantly or initiated by (fail-safe) sensors 

Again, where ventilation fans are used to ensure the discharge of a flammable atmosphere, the fan 

assembly should be suitable for hazardous areas. An emergency stop button (or buttons) must be 

provided in the machinery room (except for emergency mechanical ventilation), the action of which 

is to stop all refrigerating machinery. A remote switch must be provided outside and near to the 

machinery room door for isolating all electrical equipment not protected for use with HC 

refrigerants and for stopping all machinery. 

Fire extinguishers are to be installed in accordance with local fire authority requirements and 

notices describing their correct usage be posted. 

Figure 29: Suggestion for mechanical ventilation inlets and outlet for a machinery room 
143

5.6.5 Ventilated enclosures

As mentioned in Part 5.3, the use of a ventilation enclosure may be employed so that larger refrigerant 

charges can be safely applied to occupied spaces. In general, the type of system must be either a fully 

indirect system, where all refrigerant containing parts are within the enclosure, or a partially indirect 

system, where refrigerant containing parts are ducted directly to the outside, as illustrated in Figure 30. 

In addition, the following applies:

• There must be absolutely no potential SOIs located within the enclosure or within the ventilation duct, 

specifically, they should be of a type that cannot be modified or accidentally exposed

• Ideally, as many electrical items as practicable, should be positioned on the outside of the enclosure

• The room within which the ventilation enclosure is installed should be at least ten times the volume of 

the enclosure; this is a largely arbitrary value, but the general idea is to avoid a flammable concentration developing within the room in the event that a leak occurs during servicing of the equipment, and 

to sufficiently relieve any overpressure that may develop in the event of ignition within the enclosure

• The room must also have sufficient air inlets to enable the make up of exhausted air, i.e., it must not 

be completely air tight 

• The appliance must be designed so that it does not operate unless all of the access panels are securely 

fitted, such that refrigerant cannot enter the room

• The refrigerant-containing parts have to be isolated from the occupied space by the enclosure, such 

that in the event of a catastrophic release of refrigerant, none can migrate from the enclosure into the 

room

• The appliance enclosure must have a ventilation system that produces airflow from the appliance 

interior to the outside space, through sealed ducting, such that there is always a negative pressure 

within the enclosure

• The ventilation duct must also remain open so that if there is a leak of refrigerant and the fan is not 

operating (for some reason), then the majority of the refrigerant can migrate through the duct, in 

preference to any gaps in the enclosure walls

This negative pressure – which must be checked by measurement in the interior of the appliance enclosure – shall be 20 Pa or more and the flow rate to the exterior shall be at least 2 m3

/h or greater, according to that specified by equation 11.

 (11)

 

where Vmin is the volume flow of the ventilation (m3/h), is a safety factor = 4, is the refrigerant charge 

mass (kg), and ρr is density of the refrigerant at atmospheric pressure at 25 °C (kg/m3) (see Table 8)

The ventilation system is to be operated as follows:

• The ventilation fan is operated permanently and the fan speed or air flow is monitored, and in case of 

failure the appliance or the compressor is switched off within 10 s, or

• The ventilation fan is switched on by a refrigerant detector at a value above 25 % of the LFL, and the 

detector has to be located at a suitable point according to the density of the refrigerant

This function must be tested to ensure it performs as intended. Further, it is essential that the detector, 

ventilation and differential pressure sensor function are checked at regular intervals, and any failure 

must be indicated and the system be switched in a safe mode. The manufacturer’s instructions must 

contain these instructions, as well as a specification for the maximum length and size of the ventilation 

duct and the number of bends, so that the intended pressure drop is not exceeded.
144

Figure 30: Schematic diagram of options for ventilated enclosures
145

DEVELOPMENT OF A R290 ENCLOSURE FOR SUPERMARKET SYSTEMS 

Various options may be considered for a supermarket refrigerating system, and one such 

approach is to adopt a special ventilated enclosure comprising the entire refrigerating system, 

which provides cooling to a secondary heat transfer circuit, which is fed into the sales area.† 

The principle design approach for the refrigeration plant is for a self-contained system 

located within a gas-tight enclosure. By positioning the refrigerant-containing parts outside 

the property (e.g., on the roof top), many of the essential elements of the relevant regulations 

(i.e, the ATEX Directive) can be satisfied. Thus, particular attention is paid to the design of the 

enclosure so that when considering the rules for hazardous area, it is possible to use components which are not Ex-rated, thus being more cost efficient. In summary:

• All pipework, as connections between different circuit components, such as the heat exchanger, valves, pressure switch, control units, compressor, pumps, etc, are produced with 

brazed connections, thereby almost entirely excluding the possibility of leakage. All components and connecting lines are located within the enclosure.

• Since R290 is denser than air, it will collect at the bottom of the enclosure in case of 

leakage therefore the base is constructed as a leak-proof pan so that any releases will be 

held within the enclosure.

• Within the gas-tight enclosure, at least one gas sensor is positioned, where upon exceeding 

a pre-set concentration the gas sensor isolates the electricity supply from all electric 

components.

• There is an additional fan in the wall of the enclosure which also does not have to be 

Ex-rated; this fan ventilates the otherwise gas-proof enclosure to the ambient, primarily for 

the purpose of dissipating the heat arising from the system components (e.g., compressors).

• In the event of a release of refrigerant, the electricity supply to this additional fan is 

terminated, before the Ex-rated fan is initiated to exhaust any released refrigerant

• In addition, the electrical control cabinet within the enclosure that feeds the circuit components, is totally separated (by open ground) from the refrigeration plant – this total separation 

is necessary because in the case of an emergency, the control cabinet stays in operation.

• This remote cabinet also control the Ex-rated fan and other components in the area outside 

the enclosure, such as those associated with the secondary circuit. 

A further advantage of this approach is that the machinery for the secondary circuit such as 

pumps, etc) are also mounted within the enclosure, which provides convenience in terms of 

versatile positioning and mounting of the entire assembly, only requiring coupling to the main 

lines of the secondary circuit following its installation. Also, since the entire refrigerating 

system is factory-sealed, there is no need for strength testing, tightness testing and charging 

on-site, thereby improving overall quality control and minimising the potential for errors.

† Lidl Germany has implemented the system; refer to the case study in Part 7 for further information
146

5.6.6 Installation of pipework

When systems are installed inside, outside or in machinery rooms, there may be some additional pipework necessary, which is addressed by this section and applies equally to all situations. Also, the requirements for site-installed pipework are virtually identical to those for pipework in packaged equipment. 

There are a number of general requirements for pipework used for any type of refrigerant, for which the 

relevant publications should be referred. Here, guidelines are provided specifically for piping for HC 

refrigerants:

• The installed piping must not present a hazard for persons and free passage in escape and access routes 

must not be restricted

• No valves and detachable joints must be located in areas accessible to the general public

• Inside occupied spaces, non-permanent joints are not allowed except in the case of split units where site 

made joints directly connecting the indoor unit to piping may be permitted

• Any brazed, welded, or mechanical connections must be completed before opening the valves to 

permit refrigerant to flow between the refrigerating system parts 

• An access valve must be provided in the system to evacuate the interconnecting pipe and/or any 

uncharged refrigerating system part, if at least one part of the system is pre-charged and should 

whenever possible be located outside

• Flared connections should not be used, but where absolutely necessary flared joints should be restricted 

to use with annealed piping and to pipe sizes not exceeding 19 mm and not less than 9 mm outside 

diameter, and to locations where the joints remain exposed for visual inspection

• Refrigerant tubing and flexible connectors must be protected or enclosed to avoid mechanical damage

• Low temperature solder alloys, such as lead/tin alloys, are not acceptable for pipe connections

• If piping passes through service ducts, walkways and crawl spaces, they must be vented to a safe place 

to prevent a dangerous accumulation, that is, if the concentration could exceed the LFL

DEVELOPMENT OF A R290 ENCLOSURE FOR SUPERMARKET SYSTEMS 

This figure shows the top-view of the enclosure of the refrigeration system in connection with 

control cabinet and air-cooled condenser.

178

the Ex-rated fan is initiated to exhaust any released refrigerant 

 In addition, the electrical control cabinet within the enclosure that feeds the circuit components, is totally 

separated (by open ground) from the refrigeration plant – this total separation is necessary because in 

the case of an emergency, the control cabinet stays in operation. 

 This remote cabinet also control the Ex-rated fan and other components in the area outside the 

enclosure, such as those associated with the secondary circuit. 

A further advantage of this approach is that the machinery for the secondary circuit such as pumps, etc) are 

also mounted within the enclosure, which provides convenience in terms of versatile positioning and 

mounting of the entire assembly, only requiring coupling to the main lines of the secondary circuit following 

its installation. Also, since the entire refrigerating system is factory-sealed, there is no need for strength 

testing, tightness testing and charging on-site, thereby improving overall quality control and minimising the 

potential for errors. 

This figure shows the top-view of the enclosure of the refrigeration system in connection with control cabinet 

and air-cooled condenser. 

†

 Lidl Germany has implemented the system; refer to the case study in Part 7 for further information 

5.6.6 Installation of pipework 

When systems are installed inside, outside or in machinery rooms, there may be some additional 

pipework necessary, which is addressed by this section and applies equally to all situations. Also, 
147

• Channels or ducts should contain no electrical wiring or potential ignition sources

• Where piping passes through occupied spaces, the maximum permissible charge of refrigerant must 

not exceed the allowable refrigerant charge (see Part 5.3), or if the charge size of the system exceeds 1.5 

kg of refrigerant, the system pipework must not pass through occupied spaces

• It is possible to pass pipework through ventilated conduit so that if there is a leak of refrigerant, then it 

will pass along the conduit into the outside; in this case the conduit must be rigid, tightly sealed, 

continuous, fire resistant and sufficiently protected from external mechanical damage from disconnection and it must not be possible for others to alter or affect it in any other way

• Refrigerant piping must not be located in lift wells, public lobbies, hallways, stairways, stairway 

landings, entrances or exits, apart from the following exceptions, unless the piping has no mechanical 

joints, valves, or controls therein and are protected and accidental damage

• Marking should be applied to pipework or insulation to indicate the presence of flammable gas

Specifically in terms of piping from pressure relief devices or piping that contains refrigerant charging points:

• Piping from pressure relief devices must be discharged to a safe place

• If the discharge is to atmosphere, refrigerant must be vented via a correctly sized pipe (as required in 

the relevant standards), and at sufficient height to prevent local hazards, including the possibility of 

ignition of the discharge vapour; the use of equation (7) (see Part 5.6.3) may be used to estimate the 

safe distance

• Marking to indicate the presence of flammable gas must be placed on relief vent outlets

• Where reasonably practicable, charging points for refrigeration systems containing more than 1.5 kg of 

HC refrigerant shall be in the open air

• Marking to warn of the presence of flammable refrigerant should also be applied to charging points

Care has to be taken to exclude HC refrigerants where any welding or brazing is to be undertaken. This 

can be achieved by recovering refrigerant and purging the pipe section with oxygen-free dry nitrogen 

(OFDN). Further guidance for technicians installing pipework and components for HC systems can be 

found in Part 6.

5.6.7 Indirect or secondary systems

When HC refrigerants are used within indirect circuits, release of the refrigerant into the areas served by 

the secondary heat transfer fluid (due to leakage through the evaporator or condenser wall into the 

secondary circuit) must be prevented. This may be achieved by implementing at least one of the following options:

• Use an automatic air/refrigerant separator, within the secondary circuit on the outlet pipe from the 

evaporator or the condenser and must be at a higher level relative to the heat exchanger; the air/

refrigerant separator must have a flow rating and be rated to discharge the refrigerant that can be 

released through the heat exchanger, and it must discharge refrigerant into the vented unit housing, 

specially constructed machinery room, or outside air, or

• Use a double wall heat exchanger, between the primary and the secondary circuit, in order to avoid 

refrigerant leakage into the secondary circuit, or 

• Use a design that ensures that the pressure of the secondary circuit is always greater than the pressure 

of the primary circuit in the area of contact (such as a high-pressure HTF), or

• Use a double indirect system 

In general, where the quantity of refrigerant exceeds 25 kg, measures should be taken to detect the 

presence of refrigerant in any associated circuit containing a heat transferring fluid, for example, by 

means of a gas detector.
148

5.6.8 Use of pressure safety devices

Certain devices are sometimes required to control the pressure within the system in the event of a 

failure. The handling of pressure in this respect is the same for HCs as with any other refrigerant, and 

therefore dedicated guidelines on these matters should be referred to. However, the requirements for 

HCs tend to be slightly different and more restrictive than for non-flammable refrigerants, so a summary 

is provided here. 

In general, the need for safety devices – such as pressure relief valve (PRV) and pressure limiting switches 

– is a function of the size of the system and the upper pressures it may possibly develop, as well as other 

mechanical features of the equipment. 

Determining appropriate means of protection

As mentioned for PRVs and pressure limiting devices, Figure 31 should be used to determine the minimum means of protection against excessive pressure. This requires up to three parameters to be identified:

• Maximum allowable pressure (PS)

• Pressure equipment category (PE)

• Results of an intrinsic safety test

A summary of the required procedures is detailed below.

Maximum allowable pressure

The design pressures for refrigerating system components and the assembly shall not be less than the 

maximum allowable pressure (PS) for the system. The PS shall not be less than the saturation pressures 

of the refrigerant corresponding to specific designated temperatures, which are normally based on a 

design ambient temperature (particular to the local climate), the part of the system and the type of 

condenser. For example:

• The high pressure side of a system with air cooled condenser, PS should correspond to around 13 K 

above the design ambient temperature

• The high pressure side of a system with a water cooled condenser or hot water heat pump, PS should 

correspond to the maximum leaving water temperature plus 8 K

• The high pressure side of a system with an evaporative condenser, PS should correspond to around 11 

K above the design ambient temperature

• The low pressure side of a system, PS should correspond to the design ambient temperature

• The low pressure side of a system with a heat exchanger exposed to indoor ambient temperature only, 

PS should correspond to the indoor design temperature

Pressure equipment category 31 

The pressure equipment (PE) category requires a category to be obtained for each of the components 

within the system and the highest provides the PE category for the entire assembly. The basic methodology is as follows:

• For each component, identify whether it is a vessel (such as an accumulator, a compressors, a received, 

etc) or piping (a pipe, a valve, etc)

• If the component is a vessel, find the volume (in litres), or if it is piping, the nominal diameter (DN, 

in mm)

• Find the PS, which should normally be based on the PS value of the entire assembly

• If the component is a vessel, calculate the product of PS × volume, or if it is piping, the product of 

PS × DN

• Use Table 12 to determine the PE category

31 This is the approach defined within the European Pressure Equipment Directive (PED) (97/23/EC)
149

The highest PE category for any one component is normally the PE category allocated to the

entire assembly.

Table 12: Identification of PE Category for HC systems using small sized vessels and piping

Requirements for intrinsic safety test

This test is only applicable for equipment as indicated in Figure 31. It is primarily used for determination of the maximum pressure during abnormal operation, and both the high pressure side and the low 

pressure side are evaluated.

For determination of the pressure at the high pressure side, the heat exchanger at the high pressure side 

of the refrigeration system is subjected to following test:

• The system is installed taking into account the instructions of the manufacturer

• The system is operated at an ambient temperature of 23°C ± 5 K

• When steady conditions are attained, the flow of the heat transfer medium (e.g., air, water) to the high 

pressure side heat exchanger is restricted or shut off, whichever is the most unfavourable without the 

refrigeration system being non-operative (and if the refrigeration system is equipped with external 

heaters, they must be activated) 

The highest pressure that occurred during this test is recorded.

For determination of the pressure at the low pressure side, the heat exchanger at the high pressure side of 

the refrigeration system is subjected to following test:

• The system is installed taking into account the instructions of the manufacturer

• The refrigeration system is not operated in order to simulate standstill conditions

• The temperature of the heat transfer medium (e.g., air, water, etc) to the low pressure side heat exchanger is maintained at the maximum temperature specified by the manufacturer for 30 min (if the 

medium is a liquid) or 60 min (if the medium is air)

Type PS (bar)

Vessel Piping Vessel Piping PE

Category V (litres) DN (mm) PS × V PS × DN

if and and and and and then

Vessel >0.5 & ≤ 200

≤1 - - - < I

>1 - ≤25 - < I

>25 & ≤50 - I

>50 & ≤200 - II

Piping >0.5

- ≤25 - - < I

>25 & ≤100 - ≤250 I

>100 & ≤250 - >100 & ≤3500 II
150

The highest pressure that occurred during this test is recorded.

A hydrostatic strength pressure test is then carried out on 3 samples of each component and joints, or on 

the assembly as a total, at a pressure of 3 times the recorded pressure for the respective parts of the 

system. Alternatively other equivalent tests (such as burst test) may be used. The acceptance criterion is 

that the component or assembly under test shall not rupture.

Pressure relief valves

PRV are needed in the event of abnormal operation or an external fire to prevent the build-up of excessive pressure and subsequent pressure blast. The situation that necessitates a pressure limiting device for 

systems can be determined from Figure 31. Standard literature should be referred to for the selection and 

sizing of PRV, as well as the discharge line sizing as the same rules apply to all refrigerants. When used, 

the settings for the PRV must be according to:

• Pressure relief device setting: 1.0 × PS

• Pressure relief device that achieves the flow at 1.1 × PS: ≤ 1.1 × PS

Discharge from pressure relief devices can only take place so that persons and property are not endangered by the released refrigerant. An indication device is required to check during maintenance whether 

the relief valves have discharged to atmosphere.

Pressure limiting devices

Larger systems are normally provided with a pressure limiting device (high pressure cut-out switch), 

although the situation that necessitates their use is indicated in Figure 31. The high pressure cut-out 

shall be of the manual reset type, set to operate at the following pressures:

• Safety switching device for limiting the pressure for systems with relief device: ≤ 0.9 × PS

• Safety switching device for limiting the pressure for systems without relief device: ≤ 1.0 × PS

If used for protection of the refrigerating system against excessive pressure, they must not be used for 

control purposes; if a high-pressure switch is used for control purposes, a separate device must be fitted 

in addition, and the relevant marking applied.
151

Figure 31: Flow chart for determining the appropriate means of protection against excessive pressure
152

Temperature limiting device

Under certain circumstances a temperature limiting device may be used; this is a safety switching device 

which is approved and designed to fail-safe so that in the event of a defect or malfunction of the device, 

the power will be interrupted.

Fusible plugs and busting/rupture discs

In isolation, fusible plugs or bursting/rupture discs must not be used with HC refrigerants since once 

they melt, they will release the entire refrigerant charge, which is not desirable. However, they may be 

used in series with pressure relief valves. This has two benefits – first it helps to prevent leakage through 

the PRV seal, and second, it provides an indication that the PRV has lifted which helps to bring attention to the fact that the system may have a problem.

Arrangement of pressure indicators

For systems containing more than 1.0 kg of refrigerant, connections for pressure indicators must be 

provided (the fitting of permanent pressure indicators is optional). Where the refrigerant charge exceeds 

2.5 kg refrigerant, the system should be equipped with pressure indicators on each pressure side of the 

system (including intermediate pressure stages). It should be noted that although this is specified within 

safety standards, the logic for doing this is not evident. For example, most systems do not indicate a loss 

of refrigerant via pressure unless they are extremely low in charge, and furthermore, the addition of more 

fittings increases the possibility of leakage.

Level indicators on refrigerant receivers

Refrigerant receivers in systems containing more than 2.5 kg of refrigerant and which can be isolated 

should be provided with a liquid level indicator to show at least the maximum liquid level. On occasions 

where liquid receivers are used, an indicator can be useful anyway to alert of a loss of refrigerant.

5.6.9 Fixed refrigerant detection32 

Usually, machinery rooms must be installed with an appropriate safety system that comprises gas 

detection, ventilation equipment and alarms. In addition to machinery rooms, there may be other 

situations where permanent refrigerant detection may be employed. In general, the detectors should meet 

the following:33

• Permanently installed, and preferably multi-point sensing detectors must be fitted to satisfy safety 

requirement and alert the user or operator to the presence of leaked refrigerant

• The detector(s) should be reliable (less than 5% drift per year) and accurate (within ±3% of LFL) and 

should not be affected by other substances present in the machinery room or elsewhere

• They should have a rapid response time, for example, < 5 s at 25% of LFL

• Whilst some electronic detectors can be ‘tuned’ so that they react only to a single substance, others 

cannot discriminate between refrigerant and volatile compounds such as cleaning fluids or solvents; 

some electronic detectors can give false readings if they are contaminated with certain chemicals.

• They should be installed strategically so that they cannot be inadvertently damaged, and should be 

easy to maintain

• Detectors may be used to initiate the isolation of electrical equipment that does not conform to the 

relevant requirements (see Part 5.4) before the refrigerant reaches the Practical Limit

• The detector(s) have to function at a level not exceeding 20% of the LFL, and then automatically 

activate an alarm, start mechanical ventilation and stop the refrigerating system when it triggers

• The detector(s) must continue to function at higher concentrations, and may be used to activate 

further alarms and increase the flow rate of exhaust ventilation upon detection of higher concentrations

32 Note that fixed refrigerant or gas detection systems are not “leak detection”, they simply observe the presence of a gas at a 

particular location, and must not be assumed to provide any indication that a leak has not occurred.

33 See http://www.hse.gov.uk/pubns/gasdetector.pdf for further guidance on selecting gas detectors
153

• Detector sampling points should be located so that they provide rapid signals in the event of a leak, 

and that the effect of air movement does not inhibit their effectiveness; where the refrigerant is heavier 

than air (as is the case with most HC refrigerants), sampling points must be located at floor level

• A single detector sampling point can normally cover an area of about 30 m2

 provided it is mounted at 

floor level

• Detectors must be calibrated for the specific refrigerant they are intended to detect; be aware that 

certain types of detectors (such as corona discharge) may not necessarily be suitable for flammable 

gases if the head has not be designed correctly, so ensure that the correct types is selected 

Detectors with as fast a response time as possible should be used. Nevertheless, it should be noted that it 

could take many seconds or even minutes for a high concentration of refrigerant to be transmitted by a 

gas detector. Thus, it cannot be assumed that a gas detector will instantaneously initiate emergency 

ventilation – this needs to be taken into consideration when designing safety response mechanisms.

Where gas detection is used, robust maintenance and calibration schemes must be put in place. All types 

of gas detection are known to drift and can become contaminated over time and therefore become 

ineffective after moderate periods of time. The effectiveness of a detection and emergency system is only 

as good as the maintenance regime. 

In addition to conventional gas detection methods, other means should be employed where appropriate 

to assist with the identification of a leak. The following may be considered:

• Charge level indication, which is a means of determining whether the system is correctly charged with 

refrigerant

• Whilst factory charged systems which have few breakable joints may not require visual indicators, any 

system which is likely to need occasional service access to circuit components should be fitted with a 

liquid line sight glass

• For larger systems which would otherwise use gauge glasses, seal-less level indicators using magnetic or 

inductive or capacitive sensors should be preferred

5.6.10 Integration of system safety concepts

In principle, the initial approach to improving the level of safety of the equipment should be to optimise 

the design so as to minimise the concentration in the event of a catastrophic release. This can be 

achieved through a number of different design considerations, such as reducing refrigerant charge size as 

much as possible, positioning refrigerant-containing parts as a high a level as possible, and adjusting the 

design so as to increase air speed to help disperse a release. (These aspects are addressed in more detail in 

Parts 5.4, 5.8.5 and 5.8.6.) Appropriate correlations can be employed to identify which parameters can 

be used to reduce the concentrations for a particular construction.

Depending upon the type of system and the environment within which it is installed, it may be possible 

to incorporate additional safety concepts in order to reduce the quantity of refrigerant released, or to 

disperse the refrigerant so as to ensure a lower concentration. There are normally two aspects to this 

approach: first a sensing method to identify a potential problem, and second, an action to try to mitigate 

the problem. In practical terms these correspond to a means of recognising the release of refrigerant, and 

then an action to reduce the quantity of refrigerant that could be leaked out, or to prevent the accumulation of a flammable cloud. Table 13 includes a number of example combinations. 
154

Table 13: Example sensing methods and preventative actions and indication of effectiveness

Sensing methods

The main sensing methods are described as follows:

• Gas detection: a gas detector is used to recognise a release of refrigerant. However, this type of approach must be used with care, since, particularly in certain occupancies, the detector may get damaged if not protected well or may be subject to nuisance signals arising from other sources that are 

present in the space. Similarly, it is important that the sensor is positioned in the optimum location in 

order to have the highest likelihood of sensing the highest concentration within as short a time period 

as possible. Furthermore, most types of gas detectors require recalibration over time, which may not be 

practical in certain situations. 

• Pressure switch: a pressure switch may be used to provide an indication of a possible loss of refrigerant. 

However, the effectiveness is dependent upon the type of system, and is also sensitive to other conditions, such as the outside temperature or indoor set-point, system pull-down, and so on. This is not 

normally a particularly reliable method, so testing of the mechanism over the anticipated ranges of 

operating and environmental conditions is necessary.

• System parameter algorithm: it is possible to characterise the performance of the system – through 

parameters such as saturation pressures and temperatures and compressor current – to identify the 

deficit of charge, irrespective of environmental or other operating conditions. For example, the change 

in condensing pressure and compressor current for a given outside temperature. This can be fairly 

reliable, provided that the effects of ageing on the performance of the system are taken into account, 

and that the response time is rapid with respect to the time scale for a catastrophic refrigerant leak. 

Figure 32 shows how selected system parameters vary with a reduced charge, for a system using a 

thermostatic expansion valve and for a system using a capillary tube.

• Liquid level sensor: For systems with receivers, there will be no variation in most system performance 

parameters as the refrigerant until sufficient refrigerant has been leaked out to empty the receiver; 

depending upon the size of the received and the initial charge level, this could account for a large 

portion of the charge size. For these types of systems, use of devices such as liquid level sensors within 

a receiver may be used to identify a reduction in refrigerant quantity, although the change in receiver 

level will also vary with operating conditions which must be taken into account. 

Action

Sensing method

Gas 

detection 

Pressure 

switch 

Parameter 

algorithm

Liquid level 

sensor

Initiate extract ventilation ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔

Initiate/continue unit airflow ✔ ✔ ✔ ✔ ✔ ✔

Redirect dampers (ducted system) ✔ ✔ ✔ ✔ ✔ ✔

Shut down electrical feed ✔ ✔ ✔ ✔

Close solenoid shut-off valves ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔

Activate by-pass valve ✔ ✔ ✔ ✔ ✔ ✔

Terminate compressor ✔ ✔ ✔ ✔ ✔ ✔
155

In addition, there are certain other means of indicating a loss of refrigerant, such as flow meter type 

devices used to identify the presence of bubbles in the liquid line.34

Figure 32: Effect of reduction in refrigerant charge on selected system parameters, for a system with a thermostatic expansion device (left) and a system with a capillary tube (right) based on 35°C outside temperature

The sensing method should be used to produce an action that helps to minimise the amount of refrigerant released, or reduce the concentration of the released refrigerant or both. Figure 33 illustrates the 

effects of certain combinations. In the first case, if a leak occurs with no further action, a high concentration of refrigerant may develop within the room over the duration of the release. With the use of one 

set of measures, the concentration may be limited by using a pressure switch to pump the refrigerant into 

the outside unit, thus preventing any further build-up of refrigerant. In another case, the system parameters algorithm may be used to imitate the airflow of the unit within the room, so that the refrigerant 

is rapidly dispersed and the concentration build-up is minor. In the last case, a gas detector within the 

room is used to initiate extract ventilation which then reduces refrigerant from the space.

Figure 33: Change in room floor concentration with initiation and termination of airflow (note that this 

illustration does not indicate that one option is any more effective than another; the differences are only 

for purposes of clarity of the diagram)

34 Over recent years, there have been developments on sensors that fit into a system’s liquid line that is used to directly indicate 

the absence of refrigerant from the system (i.e., through the presence of flash-gas). Is it not known whether these have been 

commercialised to date, but such a device would present a very interesting sensing device for a safety control system.

-100% 

-50% 

0% 

50% 

100% 

40% 50% 60% 70% 80% 90% 100% 

Deviation from full charge . 

Charge 

cond press 

evap press 

subcooling 

superheat 

discharge 

temp 

compr 

current -100% 

-50% 

0% 

50% 

100% 

40% 60% 80% 100% 

Deviation from full charge . 

Charge 

cond press 

evap press 

subcooling 

superheat 

discharge 

temp 

compr 

current 

190

The sensing method should be used to produce an action that helps to minimise the amount of 

refrigerant released, or reduce the concentration of the released refrigerant or both. Figure 33 

illustrates the effects of certain combinations. In the first case, if a leak occurs with no further 

action, a high concentration of refrigerant may develop within the room over the duration of the 

release. With the use of one set of measures, the concentration may be limited by using a pressure 

switch to pump the refrigerant into the outside unit, thus preventing any further build-up of 

refrigerant. In another case, the system parameters algorithm may be used to imitate the airflow of 

the unit within the room, so that the refrigerant is rapidly dispersed and the concentration build-up 

is minor. In the last case, a gas detector within the room is used to initiate extract ventilation which 

then reduces refrigerant from the space. 

Actions 

There are a number of actions that may be considered, although their suitability will depend upon 

the type of system being used and the cost implications, as discussed: 

-100%

-50%

0%

50%

100%

40% 60% 80% 100%

Charge

Deviation from full charge

cond press

evap press

subcooling

superheat

discharge

temp

compr

current -100%

-50%

0%

50%

100%

40% 60% 80% 100%

Charge

Deviation from full charge

cond press

evap press

subcooling

superheat

discharge

temp

compr

current

Figure 32: Effect of reduction in refrigerant charge on selected system parameters, for a system 

with a thermostatic expansion device (left) and a system with a capillary tube (right) based on 35°C 

outside temperature 

Figure 33: Change in room floor concentration with initiation and termination of airflow (note that 

this illustration does not indicate that one option is any more effective than another; the differences 

are only for purposes of clarity of the diagram) 
156

Actions

There are a number of actions that may be considered, although their suitability will depend upon the 

type of system being used and the cost implications, as discussed:

• Initiate extract ventilation: this is essentially what should be used for machinery rooms (see Parts 5.6.4 

and 5.6.5)

• Initiate/continue unit airflow: airflow from an indoor air handler or condensing unit can be very 

effective in reducing the concentration of leaked refrigerant, especially if the discharge velocity of the 

air is high

• Redirect dampers: for a ducted system, dampers within the air stream that may be carrying leaked 

refrigerant from the evaporator may be redirected to vent any refrigerant to the outside

• Shut down electrical feed: this is often used in machinery rooms, but may also be used in other 

situations, where it is possible for a high concentration to develop nearby electrical components (even 

if they are protected); obviously ensuring that the switching itself does not create a source of ignition

• Close solenoid shut-off valves: if part of the system is outside, a pump-down cycle can be activated by 

using a solenoid valve in the liquid line, which will prevent refrigerant being passed to the inside space 

(see Figure 34); it is necessary to use a normally closed solenoid valve in case of failure of the electrical 

supply (under certain circumstances a valve may also be placed in the suction line but this is probably 

unnecessary since the compressor normally only leak back a small amount of refrigerant especially as it 

may encourage leakage)

• Activate by-pass valve: similar to the use of a shut-off valve, but the refrigerant is bypassed away from 

the indoor components

• Terminate compressor: compressor operation is terminated to as to prevent refrigerant being pumped 

into the inside space, and in the event that the high-pressure parts are inside, the reduction in pressure 

may help to reduce the leak rate 

Figure 34: Use of a normally-closed solenoid valve in a remote or split type system

The effectiveness of these methods will be a function of the type of system and the design of the control 

strategy, so it is important to ensure that whatever approach is used, is well tested and checked under a 

variety of different failure conditions. 

191

 Initiate extract ventilation: this is essentially what should be used for machinery rooms (see 

Parts 5.6.4 and 5.6.5) 

 Initiate/continue unit airflow: airflow from an indoor air handler or condensing unit can be very 

effective in reducing the concentration of leaked refrigerant, especially if the discharge velocity 

of the air is high 

 Redirect dampers: for a ducted system, dampers within the air stream that may be carrying 

leaked refrigerant from the evaporator may be redirected to vent any refrigerant to the outside 

 Shut down electrical feed: this is often used in machinery rooms, but may be also be used in 

other situations, where it is possible for a high concentration to develop nearby electrical 

components (even if they are protected); obviously ensuring that the switching itself does not 

create a source of ignition 

 Close solenoid shut-off valves: if part of the system is outside, a pump-down cycle can be 

activated by using a solenoid valve in the liquid line, which will prevent refrigerant being passed 

to the inside space (see Figure 34); it is necessary to use a normally closed solenoid valve in 

case of failure of the electrical supply (under certain circumstances a valve may also be placed 

in the suction line but this is probably unnecessary since the compressor normally only leak 

back a small amount of refrigerant especially as it may encourage leakage) 

 Activate by-pass valve: similar to the use of a shut-off valve, but the refrigerant is bypassed 

away from the indoor components 

 Terminate compressor: compressor operation is terminated to as to prevent refrigerant being 

pumped into the inside space, and in the event that the high-pressure parts are inside, the 

reduction in pressure may help to reduce the leak rate 

The effectiveness of these methods will be a function of the type of system and the design of the 

control strategy, so it is important to ensure that whatever approach is used, is well tested and 

checked under a variety of different failure conditions. 

Figure 34: Use of a normally-closed solenoid valve in a remote or split type system 
157

5.7 MARKING AND INSTRUCTIONS 

5.7.1 Introduction

It is important to provide warning signs, marking, and detailed information to all personnel that may 

be directly affected by the safety risks of equipment and substances. The necessity to have signage and 

instructions applies to most activities and equipment. For example:

• Warning of hazardous substances within systems, cylinders, working areas

• Requiring workers and other personnel of activities that they should do

• Making workers and other personnel aware of what they must not do

• Informing workers of the correct procedures and processes that should be carried out in relation to 

particular equipment

The use of signage, marking and instructions is normally a requirement of safety standards and 

regulations. 

5.7.2 Marking and signage

There are five main categories of safety signs; each has a different shape and colour. These are 

summarised as follows:

Prohibition 

• Description: a red circular band with a diagonal cross-bar on a white 

background

• This implies: “You must not”, “Do not do”, “Stop”, etc

• Normally there is a black symbol within the circle which denotes that a 

certain activity or behaviour is prohibited

Warning 

• Description: a yellow triangle with a black border

• This implies: “Caution”, “Risk of danger”, “Hazard ahead”, etc

• Normally there is a black symbol within the triangle which denotes 

a warning against that specific type of hazard

Mandatory

• Description: a blue solid circle

• This implies: “You must do”, “Carry out the action”, “obey an 

instruction”, etc

• Normally there is a white symbol within the circle which denotes the 

action that must be followed

Safe condition

• Description: green solid square or rectangle

• This implies: “The safe way”, “Where to go in an emergency”, etc

• Normally there is a white symbol or white text within the rectangle or

square which provides information about the safe thing to do the or 

the safe direction to go in
158

Hazardous labelling

• Description: a diamond shape, of varying colours 

• This implies that the package contains a particular hazardous substance

• Normally there is a symbol in the top half of the diamond, beneath which 

there is corresponding text which provides the primary hazard warning, 

and a hazard class number is at the base of the diamond. The colour of the 

diamond is also dependent upon the substance

Specific to the situation under consideration:

• There are a number of prohibition signs that are likely to be used, particularly in the case where 

technicians and other workers are involved with refrigerant handling and associated equipment. Figure 

35 includes a selection of possible symbols that may be adopted.

Figure 35: Some prohibition signs that may be used during refrigerant handling and other activities

“do not enter” “authorised persons only” “no smoking” “no naked flames”

• Warning signs may be applied to both the equipment and to working areas. In terms of the equipment, 

the flame warning symbol should be applied to the equipment nameplate, on remote pipework, and on 

the repair manual and must be always visible when accessing parts for maintenance. Figure 36 provides some examples of such signage. 

Figure 36: Some warning signs that may be applied to equipment and working areas

“flammable gas” “extremely flammable” “danger hazard area”

• Mandatory symbols may be applied to both the equipment, manuals and working areas. For example, 

a symbol for reading the user manual, the repair manual and the installation manual should be visible 

on equipment. It is also required that a statement requirement that the appliance must be installed, 

operated and stored in a room with a floor area larger than “X” m2

 be applied to portable appliance.

Figure 37 provides some examples.
159

Figure 37: Some mandatory signs for use on equipment

“read manual or handbook” “warning – ”

• Safe conditions symbols may be used in technician working areas and in permanent installations such 

as production lines and workshop areas, for example to indicate safe exit passages and locations of 

emergency stop buttons. Figure 38 provides some examples.

Figure 38: Some mandatory signs for use in working areas

“emergency exit” “emergency stop”

• Hazardous substance labelling, such as that in Figure 39 for flammable gases, is normally applied to 

refrigerant containers and refrigerant storage areas. 

Figure 39: “flammable gas” hazard label

The official symbols described here can be found within ISO 3864, ISO 7000 and IEC 60417.35

35 see http://www.graphical-symbols.info/ 
160

5.7.3 Manuals and other instructions

Sets of instructions, in the form of manuals, guidance notes, data-sheets, etc, should be provided for 

both training and a source of reference for nearly all stages in the equipment life. In particular, manuals 

and other guidance should be provided for:

• Design of equipment and installations

• Manufacturing, operation of production line equipment and assembly

• Operation and working of the production area safety system

• Storage and distribution of equipment

• Installation of the systems and/or equipment

• Service, maintenance, dismantling and disposal of the systems and/or equipment

• Operation of the systems and/or equipment for the user

Specifically for equipment using flammable refrigerants, it must be accompanied by further instructions, 

including at least the following:

• The information with which the equipment is marked, together with any appropriate additional 

information to facilitate maintenance (e.g. address of the importer, repairer, etc)

• Instructions for safety: putting into service, use, assembling and dismantling, maintenance (servicing 

and emergency repair), installation, adjustment, an indication of the danger areas in front of pressurerelief devices (when used)

• Where necessary, training instructions

• Details which allow a decision to be taken beyond any doubt as to whether an item of equipment in a 

specific category or a protective system can be used safely in the intended area under the expected 

operating conditions

• Electrical and pressure parameters, maximum surface temperatures and other limit values

• Where necessary, special conditions of use, including particulars of possible misuse which experience 

has shown might occur

• Where necessary, the essential characteristics of tools which may be fitted to the equipment or protective system.

On being put into service, all equipment must be accompanied by a translation of the instructions in the 

language or languages of the country in which the equipment is to be used (and by the instructions in 

the original language). Instructions must contain the drawings and diagrams necessary for the putting 

into service, maintenance, inspection, checking of correct operation and, where appropriate, repair of the 

equipment, together with all useful instructions, in particular with regard to safety. Ensure that literature describing the equipment must not contradict the instructions with regard to safety aspects.

Depending upon the size of the enterprise that is producing the equipment, the type of systems and 

equipment, and other factors, the manuals may be separate for each stage (or sub-stage), or the manuals 

for certain stages may be combined. In any case, the information must be complete and include all the 

relevant instructions and data for the equipment to be used correctly and safely. Of utmost importance is 

that any such instructions should be written clearly and concisely so that everyone can comprehend it 

correctly; ensure that any reader will understand exactly what the manual intends. 

Table 14 provides an overview of the type of information the manuals applicable for each general stage. 

The relevant information on safety is mostly available within the relevant sections of this publication. 

However, this only applies to safety and flammability aspects; there is of course other material that 

should be included in all cases. 
161

Table 14: Overview of the general information required for manuals Table 1: Overview of the general information required for manuals

Stage (and target groups)

Relevant Part

of this

handbook

Design (design/ development

engineers)

Manufacture (production

workers, supervisors,

maintenance staff)

Storage and distribution

(warehouse staff, supervisors,

delivery staff)

Installation (installation

technicians)

Service and maintenance

(service/ maintenance

technicians)

Operation (appliance/ system

users or operators)

Basic flammability safety 1.2.1 9 9 9 9 9 9

Refrigerant safety classification 1.2.2 9     9 9 9

Basic working with HCs 1.2.3 9 9 9 9 9

Regulations 1.5.2, 1.5.3 9 9 9      

Principles RAC safety standards 1.5.4 9     9 9

Technician tools and equipment 3.2.3        9 9

Production site refrigerant supply 4.2    9        

Equipment for appliances production 4.3    9        

Safe operation of production line   4.4    9        

Workshop and repair areas 4.5    9 9    9

Principles safe design 5.1 9     9 9

Design for avoiding leakage 5.2 9     9 9

Refrigerant charge size limits 5.3 9     9 9

Avoiding sources of ignition 5.5 9 9 9 9 9

Outdoor installation requirements 5.6.1, 5.6.3 9     9 9

Machinery rooms 5.6.4, 5.6.5 9     9 9

Component installation and selection 5.6.6, 5.6.7 9     9    

Fixed gas detection 5.6.8 9    9 9 9

Marking 5.7.2    9 9 9 9 9

Risk analysis 5.8 9           

Refrigerant handling procedures 6.1, 6.3, 6.5    9 9 9 9

Commissioning of systems 6.3        9 9

Retrofitting, retro‐filling systems 6.4          9

Pressure‐temperature data A.1 9      9 9

Flammability characteristics A.3 9 9    9 9

Refrigerant use sheet A.8        9 9

Refrigerant safety data sheet [supplier] 9 9 9 9 9 9
162

Whilst Table 14 refers to particular sections within the handbook, the actual material within the manuals or other documentation does not need to be exactly reproduced, but the relevant material may be 

used to assist with building up the documentation. Depending upon the set up of the facility under 

consideration or the type of systems and equipment being referred to, differing material will be required. 

Similarly, the depth of the information provided within the documentation will vary according to the 

type of activity under consideration and also the complexity of the systems and equipment.

In order to check that the instruction manuals are of sufficient quality, they should be “tested” by having 

trials of less-competent persons try to follow the relevant instructions, and to assess the adequacy of the 

subsequent work and obtain their feedback.
163

5.8 RISK ANALYSIS

5.8.1 Introduction

Risk analysis, typically in the form of a quantitative risk assessment (QRA) and other techniques, should 

be carried out on systems and equipment that uses flammable refrigerants. The main reasons for carrying out a risk analysis are:

• To ensure that a detailed safety evaluation has been carried out, since safety standards are only on 

qualitative assumptions about risk, made by working groups, committees, etc, and thus are not always 

robust for all situations

• To enable the identification of ways and means to improve the level of safety of the systems and 

equipment, by way of detailed investigations of all of the factors that affect the risk

In particular, the use of risk analysis helps to avoid emotive descriptions such as “safe” or “unsafe”. 

Furthermore, because the approach is intended to represent a real life case, the use of “safety factors” and 

“worse case” assumptions are not applied. It also provides a useful medium for achieving a rational 

understanding of flammability risks associated with the use of HC refrigerants. In general, if there is 

little knowledge and understanding of the risks and the components of the risk associated with the use of 

a particular technology, the safe design, use and operation of equipment will have many uncertainties 

associated with it. This leads to a more risky situation. However, if those involved attain a greater 

knowledge and understanding of the issues, then a much higher level of certainty in the safe design, use 

and operation will be achieved. This ultimately leads to a reduced level of risk.

5.8.2 General risk assessment techniques

Determining the risk of something is to estimate the likelihood of harm that a particular hazard, or set 

of hazards, may cause to people or property. The risk itself is a product of the likelihood of an undesirable event happening, and the severity of that undesirable event. Thus to carry out a risk assessment it is 

necessary to identify and analyse the hazards, estimate the risks, and using this output determine 

possible risk-reducing measures. 

There are four common techniques for carrying out a risk assessment: hazard and operability study 

(HazOp), failure modes and effect analysis (FMEA), event tree analysis (ETA), and fault tree analysis 

(FTA). These may be used individually or together.

To carry out such activities, it is important to obtain qualitative and quantitative data based on past 

experience; on occasions when this is not possible, experiments and calculation may be used as a means 

to obtain the appropriate information on the hazards and contributing events and processes. When 

analysing events and processes related to equipment and installations, it is essential to ask open questions, such as “how...?”, rather than “what...?”, so that a wider understanding is gained (i.e., “how does 

this event occur?”, not “what event occurs?”). Furthermore, the risk analysis should be carried out by a 

team covering the necessary expertise. At least, it should include:

• Specialist(s) on the design, construction and operation of the system/equipment/installation under 

consideration

• Specialist(s) on the physical and chemical mechanisms that result in the hazards under consideration

• Reviewer(s) to check the reasonableness of the overall assessment

In addition, there are a number of standards that may be directly or broadly applicable to risk assessment 

of the situation or equipment under consideration, and these should be sought.36

36 See for example, EN 15198 – Methodology for the risk assessment of non-electrical equipment and components for intended use 

in potentially explosive atmospheres; EN 1127 – Explosive atmospheres. Explosion prevention and protection; EN 15233 – Methodology for functional safety assessment of protective systems for potentially explosive atmospheres
164

The output of any such study should include identification of any items, locations, set of conditions, 

activities that lead to the greatest risk, and present approaches to target these, which should be ranked in 

order of priority. 

Failure modes and effect analysis (FMEA)37 

FMEA primarily addresses the effects of failures or malfunctions of individual components (or process 

actions) within a system, with the objective of identifying which components are the most critical and 

thus, which require greatest consideration. The overall approach requires each component to be listed 

and a thorough series of questions asked (such as those in Figure 40 regarding the manner of its failure 

and the possible outcomes in the event of it failing. 

Figure 40: Questions to be asked for each component within a system as part of an FMEA

Table 15: Example of some FMEA questions for fixed flammable gas detection sensor

37 Guidance can be found in IEC 60812 – Analysis techniques for system reliability – Procedure for failure mode and effects 

analysis (FMEA)

How fail? Causes of? Effects of? How serious? How detected? How remedied?

No signal Faulty 

connection

No alarm or 

venting

High Regular test 

signal

Manual repair

No signal Contaminated 

sensor

No alarm or 

venting

High Regular test 

sample

Manual 

replacement

No signal Covered sensor No alarm or 

venting

High Regular test 

sample

Manual action

False signal Contaminant in 

air

Other gas leak Low Alternate 

detector

Alarm signal

... ... ... ... ... ...
165

Finally, for a system or overall installation, a summary sheet should be prepared which presents the 

failure modes in a prioritised sequence, making it obvious which elements require most attention. This 

should be complimented with corrective actions or measures, which could be design changes, new or 

changed procedures or processes, servicing or maintenance plans, organisational changes, and so on. 

Figure 41: Example of determination of risk on the basis of the frequency of an undesirable event occurring and the cost-severity of the damage cause by the consequence of the event; “A” is unacceptable, “G” 

is acceptable 

An example of how such an analysis may be carried out is provided in Table 15.

For each failure the level if risk should be identified. This is carried out by:

(i) Estimating the severity of each failure, which may be categorised from negligible or minor to 

catastrophic, and

(ii) Estimating the probability of each failure – typically from experience and/or calculation – which 

may range from improbable to frequent.

From the product of severity × probability, the risk of each failure can be determined. Thus a failure that 

has minor severity and is very improbable does not present a problem. However, a failure that is likely to 

occur very frequently and has a catastrophic severity must be addressed further. Figure 41 illustrates this 

concept, by means of quantifying different levels of frequency of an event, and severity of the consequences (in terms of cost). The most desirable situation falls under “G”, whereas the least favourable is 

“A”. Note also that if a component is linked to others (as it nearly always the case) either mechanically or 

procedurally, then the ultimate consequence may be significantly more (or less) severe than initially 

indicated; it either case it must be accounted for. 
166

Event tree analysis (ETA)38 

ETA is a logic-based technique, characterising the likelihood of hazards occurring according to contributing events not occurring or occurring. This approach is commonly used to analyse situations involving 

releases of flammable or toxic gases.

Essentially, each possible event leading up to one or more end consequences, starting with one or initiating event, must be listed, and a probability assigned to each of these events. The initiating event may be 

a component failure, a change in condition, a human action or some other occurrence, whilst the end 

consequence may be an ignition event, overpressure, fatality, property damage, and so on. Starting from 

the initiating event, a sequence of paths are plotted in order to identify the consequences of each possible 

event. The occurrence of each event (and non-occurrence of the event) has a probability assigned, from 

which the overall probability of the end consequence is determined. 

An example of an event tree for a release of flammable gas from a pipe, leading to possible ignition, is 

presented in Figure 42.

Figure 42: Example of event tree for a flammable gas release from a pipe

Fault tree analysis (FTA)39 

FTA is another technique that combines a graphical approach and estimated probabilities to determine 

the likelihood of undesirable outcomes. It helps to systematically develop an overview of the possible 

events leading to one or more consequences. 

It is carried out by first identifying the most serious consequence, or ‘top event’. From that, the fault tree 

is constructed in a manner that relates the sequence of events that ultimately lead to the occurrence of 

the top event. Usually, it is produced using a series of the logical ‘AND’ and ‘OR’ gates, which represent 

the combination of conditions required to satisfy the subsequent event. For each event, a probability 

should be assigned. Where two or more events are necessary for the subsequent event to occur, then an 

AND gate is used and the probabilities multiplied. Whereas if the prior event may act independently to 

result in the subsequent event, an OR gate is used and the probabilities summed. 

Figure 43 is a basic illustration of a fault tree, showing the failure of the protection of a SOI events and a 

release of flammable gas events, leading to the top ignition event.

38 Guidance can be found in IEC 60812 – Analysis techniques for system reliability – Procedure for failure mode and effects 

analysis (FMEA) 

39 Guidance can be found in IEC 62502 – Analysis techniques for dependability – Event tree analysis
167

Figure 43: Example of a fault tree leading to a top event of ignition of flammable gas by an unprotected SOI

Hazard and operability study (HazOp)40

A HazOp is not actually a risk assessment technique (by definition), but it provides a useful means of 

gaining insight to the possible hazards posed by systems and installations, which can then be quantified 

by other means. Broadly, to carry out a HazOp requires a series of “what if?” questions to be asked about 

a particular process, system or workings of an installation. It is used to systematically examine the 

manufacturing, design, construction, installation, operation and service and maintenance activities of 

systems or equipment. 

Figure 44 is a flow chart with the typical HazOp procedure. Initially the boundaries of the system, 

equipment, activities, etc, need to be established, which then needs to be broken down into individual 

elements for examination. For each element, certain guide words should be used to examine the possible 

“deviations” (i.e., problems, faults, mistakes, etc) in operation. These guide words are generally:

• “no” or “none” g the negation of the intention

• “more” g a quantitative increase

• “less” g a quantitative decrease

• “as well as” g in addition to

• “part of” g a qualitative decrease

• “reverse” g the opposite of the intention

• “other than” g a complete substitution

40 Guidance can be found in the standard IEC 61882 – Hazard and operability studies (HAZOP studies) – Application guide
168

For each of the deviations identified, the causes should be then sought, since these may be used to help 

prevent the deviations. Similarly, the existing design and associated controls should be checked in order 

to determine if or how they prevent the deviation. Next, the consequences of the deviations must be 

identified, and subsequently, and estimation of the risk arising from the deviation, possibly using the 

same approach detailed in Figure 41. If the risk is unacceptably high, then alternative means of handling 

the deviation need to be developed. The entire process should be carried out for all elements within the 

chosen boundary.

Figure 44: Typical work flow diagram for carrying out a HazOp analysis

To illustrate the approach, an example is given of a technician charging HC refrigerant into a system. A 

number of possible deviations are listed based on the guide words: 

• “no” or “none” g e.g., no electronic balance, hose connection loosens

• “more” g e.g., overcharged refrigerant, pressure too high

• “less” g e.g., insufficient refrigerant in cylinder, lack of ventilation

• “as well as” g e.g., SOI present nearby, air in the system

• “part of” g e.g., no gas detector present, valve cap not replaced

• “reverse” g e.g., backflow from system, back-seat instead of front-seat manifold valve

• “other than” g e.g., untrained technician, wrong hose connection

A selection of these is included in Table 16 as examples.
169

Table 16: Example application of HazOp to HC refrigerant system charging during servicing

5.8.3 Specific methodology

This section presents a methodology for quantitative risk assessment (QRA) of flammable refrigerants in 

RAC systems. It is intended to provide a general approach to quantifying the main individual events – in 

terms of probabilities – that lead to a given consequence and the evaluation of that consequence. 

Figure 45: Basic sequence of events causing a hazard from flammable refrigerants

Figure 45 provides a basic overview of the sequence of events that lead to undesirable consequence and 

hazards: RAC component failure leading to a refrigerant leak g creation of a flammable mixture g

ignition of the mixture g consequence event g damage. The first output of interest from a QRA is the 

frequency of ignition – expressed as the number of occurrence of an event per unit time, for a specific 

RAC equipment design, within a particular environment. The second output is the severity of the 

consequences caused by that ignition event.

Deviation Cause of 

deviation

Consequence Existing

controls

Possible actions

Hose connection 

loosens

Insufficient 

tightening

Release of gas Manual stop valve Use gas detector, 

activate emergency airflow

Overcharged 

refrigerant

Poor manual 

control

Pressure relief 

activates, system 

part ruptures

Manual weight 

check

Recover refrigerant, activate 

emergency airflow

SOI present nearby Technician not 

checked area

Ignition of release None Reminder alarm, 

have checklist

Valve cap not 

replaced

Technician forgot Slow release of 

gas

Instructions, signs Valve-to-cap 

connecting string 
170

Whilst the use of QRA should be applied to many of the stages during the lifetime of the equipment, 

the phases that are focussed on here are those during the in-use stages. In particular:

• In-use operation of the systems

• During service and maintenance (refrigerant handling)

• During storage (if applicable)

The two groups of persons at risk during these activities should also be considered:

• Member of the public 

• Workers (technicians) 

Lastly, the locations under consideration must also be addressed, which relate to the presence of the 

refrigerant-containing parts, typically:

• Ignition of flammable mixture within a room (occupied space or machinery room)

• Ignition of flammable mixture within the equipment’s indoor enclosure or housing

• Ignition of flammable mixture outside (in the open air)

• Ignition of flammable mixture within equipment’s outdoor enclosure or housing

A map of these concepts is provided in Figure 46.

In general, the risk of ignition for an outside location is normally much smaller than for an indoor 

situation, due to the large area and high rates of ventilation. Similarly, due to the wide variety of conditions and the very small quantities of gas anticipated to be released, the calculation of the risk can be 

rather uncertain. Although the discussion hereafter therefore relates more so to releases inside occupied 

or enclosed spaces, consideration must also be given to outside areas. 

Figure 46: Map of modes, locations and target groups to consider in risk analysis

When evaluating the risk, a wide number of conditions should be accounted for

• Use mode: normal operation, storage, servicing, maintenance

• Operating mode: compressor on or off

• Unit airflow condition: off or on, different flow rates

• Mechanical ventilation: off or on, different flow rates

• Presence of thermal sources
171

• Infiltration and natural ventilation: different rates according to environmental conditions

• Presence of SOIs: different positions, different types

• Leak size: ranging from very small to very large

• Controls: failure of control circuits, detectors, fans, valves, etc

In order to properly evaluate the probabilities described above, it is useful to have an understanding of 

the physical processes that lead to them. Therefore a discussion of such aspects as refrigerant flammability characteristics, refrigerant leakage, dispersion of refrigerant leaks and overpressure and thermal dose 

is presented later.

Frequency of ignition

An ignition event is coincidence of three fundamental events: 

• Occurrence of a leak, 

• Development of a flammable-refrigerant/air mixture at a specific location, and

• Co-existence of a source of ignition being “active” within the flammable mixture.

These events have their individual probabilities or frequencies, and the frequency of ignition ( f* ) is 

essentially the product of these. The ignition frequency of a single leak under a particular set of conditions (f*) is calculated from equation (12).

 (12)

where f leak,i and Pi

F*

 are leak frequency and probability of ignition of a flammable mixture by an active 

SOI, respectively. f leak,i refers to a specific leak size in terms of duration, under a set of conditions and is 

largely related to the construction/installation of the system and compressor operating mode (on- or 

off-cycle), and is normally based on empirical (and anecdotal) data. i represents each individual set of 

operating and environmental conditions. Pi

F*

 may be evaluated with respect to a vertical element/region 

within the room so that sources of ignition (SOI) are linked to local formation of a flammable mixture 

(in light of the relative buoyancy of the gas). 

To account for the dynamic nature of equipment operation and/or associated environment, fi

* is 

normally evaluated for each set of conditions, such as compressor operating mode and the presence of 

alternate or multiple airflow types. Consequently, the overall ignition frequency (f* ) is the sum of the 

individual ignition frequencies for all leak sizes, weighted with the corresponding time fraction for each 

combination of conditions – compressor operating mode and each airflow type – that is present (equation 13).

 (13)

with each φj

 referring to different operating modes, infiltration rate, presence of thermal currents, 

mechanical ventilation, and so on.

For determining the probability of ignition (Pi

F*

) for an active source of ignition (SOI) surrounded by 

a mixture at a flammable concentration (CF

) within an enclosed space, the characteristics of each 

individual SOI should be accounted for. For a given space-time, ignition could potentially occur when 

an active SOI is present at the same time and spatial position as CF

, as illustrated in Figure 47. The 

coincidence of these leads to ignition, as indicated by the blackened area. To determine PF*

, it is evident 
172

that two component probabilities are needed: probability of an active SOI at the same time as CF, and 

probability of CF

 at the same spatial position as the potential SOI. Pi

F*

 is determined from equation (14).

 (14)

where Pv

F is the probability of a flammable volume, Psoi is the probability of an active source of ignition, 

Nsoi is the number of SOI, and NE is the number of active events of each SOI. Pv

F

, and therefore PF*, is 

a function of the size and duration of a flammable mixture, influenced by many parameters, including 

charge size, leak duration and airflow conditions, arising from infiltration, convection by thermal 

sources, evaporator and/or condenser fans, and various forms of mechanical ventilation, and requires 

modelling of a release to determine relevant characteristics.

Figure 47: Venn diagram indicating occurrences necessary for ignition

Occurrence of SOI events

Within a given space, an active SOI may be present on the RAC equipment or elsewhere within the 

room, and on tools used for servicing activities. For a single active SOI event assumed to occur for some 

duration randomly within a reference period, the probability of its occurrence can be given by the ratio 

of the duration of the SOI to the duration of that reference period. Similarly, if a flammable volume 

event occurs randomly over a given duration within the same reference period, the probability of the 

flammable concentration being present is the ratio of the duration of that flammable concentration to 

the reference period. As the SOI event and the flammable volume event are independent, the probability 

of them occurring simultaneously within the same reference period is the sum of both probabilities. 

Therefore, the probability of the SOI event being present at the same time as the flammable concentration can be written as equation (15), showing the probability of an active SOI within a flammable 

volume within a given reference volume under a given set of conditions resulting from a certain leak size 

(in terms of duration). 

 (15)

where Pavail is included to account for the availability of the SOI (e.g., if electrics are protected against 

ingress of refrigerant, Pavail = 0, or the integrity of protection may fail, 0 < Pavail < 1; otherwise, for 

permanent SOI, Pavail = 1.)
173

The significance of the positioning of the sources of ignition should also be considered, since the probability calculations require the room be divided into three levels of equal volume to account for the locality of SOI. If there is a major proportion of the flammable concentration occurring consistently within 

the upper levels of the room, then all SOI should be addressed, however, if the majority remains within 

the lower level, then it may be possible to account only for the SOI around the floor level. Values of the 

ratio of flammable volume-time existing within the lower level of a room (below 1 m) to total flammable 

volume-time for a variety of different situations are shown in Figure 48 as a percentage of cases that have 

a proportion the flammable volume-time below the height of 1 m within the room, relative to the total 

arising from a given release. It is seen that some 70% of the cases have at least 90% of their flammable 

volume-time existing in the lower level, and 85% of cases with at least 80% of the flammable volumetime within the lower layer. It is therefore considered acceptable to only account for the SOI at floor level. 

Figure 48: Proportions of flammable volume-time being present within the lower level for a variety of 

different situations

Occurrence of flammable volume events

The probability of having a flammable volume (Pv

F

) is based on the coincidence of the active SOI being 

present in the same spatial location as the flammable concentration. For this, it is assumed the SOI are 

located randomly within the same reference volume that the flammable concentration may exist, thus 

the need for Pv

F

. Thus there are two possible outcomes: a flammable concentration event occurs within a 

given location representing a flammable volume, or the concentration < LFL. This probability is the ratio 

of the number of flammable volume events to the total possible events for the flammable volume to 

occupy, where the number of events is interpreted as total volumetric elements, so the probability of the 

flammable volume is given by (equation 16).

 (16)

where the reference volume V ́ corresponds to the horizontal levels chosen for grouping local SOI

 , and is the mean flammable volume existing within that reference volume. 

Psys is the probability of a system to release its charge, also interpreted as “annual leak rate” or the ratio 

of total mass leaked from a given population of systems to the refrigerant bank. Pperc is percolation 

probability which is failure to ignite a CF

 due to small pockets of unmixed gas or air within a cloud.

210

The significance of the positioning of the sources of ignition should also be considered, since the 

probability calculations require the room be divided into three levels of equal volume to account for 

the locality of SOI. If there is a major proportion of the flammable concentration occurring 

consistently within the upper levels of the room, then all SOI should be addressed, however, if the 

majority remains within the lower level, then it may be possible to account only for the SOI around 

the floor level. Values of the ratio of flammable volume-time existing within the lower level of a 

room (below 1 m) to total flammable volume-time for a variety of different situations are shown in 

Figure 48 39 as a percentage of cases that have a proportion the flammable volume-time below the 

height of 1 m within the room, relative to the total arising from a given release. It is seen that some 

70% of the cases have at least 90% of their flammable volume-time existing in the lower level, and 

85% of cases with at least 80% of the flammable volume-time within the lower layer. It is therefore 

considered acceptable to only account for the SOI at floor level. 

0% 20% 40% 60% 80%

0-10%

11-20%

21-30%

31-40%

41-50%

51-60%

61-70%

71-80%

81-90%

91-100%

Percentage of flammable volum

within the lower level

Proportion of cases

Figure 48: Proportions of flammable volume-time being present within the lower level for a variety 

of different situations 

Occurrence of flammable volume events 

The probability of having a flammable volume ( F PV ) is based on the coincidence of the active SOI 

being present in the same spatial location as the flammable concentration. For this, it is assumed 

the SOI are located randomly within the same reference volume that the flammable concentration 

may exist, thus the need for F PV . Thus there are two possible outcomes: a flammable concentration 

event occurs within a given location representing a flammable volume, or the concentration < LFL. 

This probability is the ratio of the number of flammable volume events to the total possible events 

for the flammable volume to occupy, where the number of events is interpreted as total volumetric 

elements, so the probability of the flammable volume is given by (equation 16). 

′

F

F h

V,i sys perc

h

=V P P P

V (16) 

 

39 from Colbourne and Suen (2008a) 

Proportions of cases

0% 20% 40% 60%

91-10%

81-90%

71-80%

61-70%

51-60%

41-50%

31-40%

21-30%

11-20%

0-10%

Percentage of flammable volume

within the lower level
174

Flammable volumes

In carrying out a quantitative risk assessment (QRA) on the likelihood of ignition, it is important to be 

able to accurately estimate the size and duration of a flammable region that has arisen due to a leak of 

refrigerant for any set of conditions. There are a variety of different approaches that may be used for this 

purpose. These may include:

• Computational fluid dynamics (CFD)

• 2-D or 3-D zonal decay models

• Gaussian models

• Simplistic methods

The choice of approach for estimating the flammable volume and flammable time will be dependant 

upon the resources available, the necessary accuracy, the availability of validation data, and so on. In any 

case, it is useful to consider the three distinct processes that may arise from a refrigerant release:

• Descending plume: When a leak develops within the refrigerant circuit, it produces a high velocity jet, 

which may impinge on a surface or flow directly into an open space in any direction, but eventually 

gives way to buoyancy forces and a relatively low velocity plume is formed that falls towards the floor, 

whilst increasingly entraining more air from the surroundings causing it to dilute.

• Spreading plume: If the descending plume approaches the floor with a concentration at or above the 

LFL, the plume is considered to spreads across the floor. As this happens, the flow entrains air from 

above and subsequently dilutes further. As the descending plume continues to the floor, the new denser 

front displaces the existing diluted mixture thereby creating an upper layer, and each successive layer 

entrains material from the layer above it.

• Cloud decay: At the end of the release, if any of the mixture is at or above LFL then a cloud is considered to be present. The concentration within the cloud tends to decay in a similar manner to that for 

the spreading plume in terms of entrainment of the more dilute mixture from above. However, there is 

negligible horizontal flow across the floor (due to cessation of the descending and spreading plume) so 

whilst a velocity gradient between the layers still exists due to the air movement within the room the 

rate of entrainment is at a slower rate.

In carrying out calculations to evaluate these processes, it is also essential to account for the various 

sources of airflow, including unit airflow, mechanical ventilation, infiltration, and thermal convection.

Consequences

The ignition event can result in one or more “primary” consequences, which depend upon the local 

conditions: a jet fire, a flash fire, and/or an explosion (which is characterised by the development of 

sufficient overpressure from the expansion of the gases). The interaction of these primary consequences 

with the surroundings, lead to possible “secondary” consequences: thermal damage from radiated heat, a 

secondary fire perhaps due to flame impingement or sufficient overpressure to cause damage to property 

and/or people. To account for these, intensity of thermal radiation and overpressure (within the room) 

were used to evaluate consequence, from where the individual risk of fatality (associated to the installation) is estimated. Frequency of fatality (ffatal) is the sum of individual fatality frequencies resulting from 

each fi

* (equation 17). 

 

 (17)
175

where Nocc,i and φocc,i are the number of occupants and their residence time fraction, respectively. 

 is the probability of fatality due to thermal intensity applied to an occupant (Iocc) and/or room 

overpressure ( Δρ°

Rm ) corresponding to the conditions for fi

*.

The probability of fatality associated with a dose of thermal radiation can be calculated, for example 

from equation (18), when 0 < Pfatal < 1.

 

	 	 	 	 	 (18)

where a = - 3.79 and b = 0.54.

The probability of fatality due to overpressures can be calculated, for example from equation (19), when 

0 < Pfatal < 1.

	 	 	 	 	 	 	 	 	 	 	 	 	 (19)

where a = - 3.62 and b = 0.76. 

Overall risk

In order to represent the overall risk impact posed by an installation, the use of integrated thermal 

intensity-frequency (equation 20) and integrated overpressure-frequency (equation 21) may be used. 

They represent the time- and severity-weighted consequence of ignition. 

 (20)

 

 (21)

Alternatively, for a single set of conditions, the discreet risk can be found from the product or for the 

risk due to thermal intensity or overpressure, respectively.

Acceptability of risk

It is necessary to put the calculated risks into context if equipment is to be judged as “safe” or “unsafe”. 

This was achieved by establishing certain limits to compare against the outcome of the QRA, indicating 

an acceptable or unacceptable risk considering: frequency of ignition and frequency of fatality. Ignition 

risk may be interpreted as fire risk, since ignition may lead to a secondary fire. In this respect, it is useful 

to compare the risk of RAC equipment against risks from, say, domestic refrigerators (non-HC), which 

have a value of 1.1×10-5 y-1, which is evidently considered “acceptable” by society. For fatality risk, the 

UK Health and Safety Executive recommend values for “negligible” risk to an individual: member of the 

public ffatal = 1×10-6 y-1, and service industry worker ffatal = 1×10 10-5 y-1. Thus calculated ffatal should 

be lower than these. A summary of the suggested acceptable risk criteria is given in Table 17.
176

Table 17: Suggested maximum acceptable risk criteria

Often the output of a QRA can be considered by plotting a frequency-consequence curve, for example, 

such as that in Figure 49. This example is for the ignition of a flammable refrigerant that has leaked 

into the indoor unit, outdoor unit and into the room, when the airflow is either on or off. Using this 

approach is a useful tool for observing the overall risk, and in particular, helping to identify the situations that could be potentially high-risk. The figure is divided into four sections, where the upper right 

quadrant represents the region of “significant risk” (i.e., severe consequence occurring with high frequency), and the lower left quadrant representing the region of “negligible risk” (i.e., negligible consequence 

occurring with low frequency). Where risk values land within the regions of high risk, consideration can 

be given to design or procedural changes so that the risk can be reduced.

Figure 49: Example of a frequency-consequence curve for ignition of flammable refrigerant from different 

sized leaks into the indoor unit, outdoor unit and occupied space for an air conditioner

Criteria

Limits

To members of public To members of public

Frequency of ignition (fire) (f* ) < 1×10-5 y-1 < 1×10-5 y-1

Thermal intensity (Iocc) < 1050 s (kW m-2)4/3 < 1050 s (kW m-2)4/3

Overpressure (Δρ°

Rm) < 250 kPa < 250 kPa

Frequency of fatality (ffatal) < 1×10-5 y-1 < 1×10-6 y-1

0,0001 

0,001 

0,01 

0,1 

1 

10 

100 

1E-11 1E-9 1 E-7 1E-5 1 E-3 1E-1

Maximum overpressure (kPa) . 

Ignition frequency (/yr) 

indoor unit 

outdoor unit 

room (off-cycle)

room (on-cycle)

negligible risk 

indoor unit 

outdoor unit 

room (off-cycle)

room (on-cycle)

negligible signficant

negligible

significant risk

significant
177

5.8.4 Flammability characteristics

The flammable characteristics of a substance also affect the risk in various ways, so it is important to 

consider these characteristics in light of the environment within which they will be used. The following 

provides a brief introduction to the aspects to be considered.

Lower and upper flammable limits – The flammability limits, and in particular, the LFL are used to 

relate the size of refrigerant charge to the dimensions of the spaces that the equipment may be located in. 

In addition, it is required for determining air flow rates for extract ventilation. They are also critical for 

the operation of refrigerant detectors in terms of set values. 

Minimum ignition energy and auto-ignition temperature 

These characteristics are primarily related to the consideration of sources of ignition. Both on the RAC 

equipment, and in certain cases, in the surrounding area, it is important to avoid potential sources of 

ignition. Ensuring that any potentially hot surfaces have a sufficiently low temperature, or devices that 

could produce an electro-static charge above the minimum ignition energy helps reduce the hazard. 

Similarly, service and maintenance technicians can consider the use of their tool and how they work on 

equipment with respect to these characteristics.

Heat of combustion, adiabatic flame temperature and laminar flame speed

These characteristics are of primary use when carrying out risk assessments. In particular these help 

understand the severity of the consequences of an ignition event. For example, the amount of thermal 

radiation emitted and the strength of a pressure wave caused by an explosion.

Refer to Appendix 4 for a detailed explanation of the flammability characteristics.

5.8.5 Refrigerant leakage

In carrying out risk assessments, it is essential to ensure that the leakage characteristics are well known, 

so that they can be represented precisely. Thus gathering empirical data on leakage is a vital exercise. In 

particular, the following information should be sought:

• Positions of the system where leaks arise from, and the locations

• Reasons for the leakage (corrosion, mechanical connections, broken seals, etc)

• Release rate

Such information should be drawn from as large a population of equipment as possible in order to 

achieve a sufficiently representative data-set. Furthermore, additional details should be recorded such as 

the age of installation, local environmental conditions, etc. It is also beneficial to request service and 

technician staff to record how much refrigerant they added to a system in order to get an impression of 

the size of the leaks. 

Taking a systematic approach to leak analysis can yield benefits in terms of reliable quantitative data on 

leakage and appropriate means of mitigation. Table 18 provides some examples of possible causes of 

leaks.

For each cause of leakage, it is important to understand the conditions and mechanisms that lead to such 

a leak occurring, what the likelihood of them occurring with the system and anticipated conditions 

under consideration. A useful tool to carry out such an analysis is FTA (see Part 5.8.2). Latterly, what 

measures can be put in place to prevent those mechanisms and thus the leak from developing. Note that 

different types of failure apply to some piping materials (such as steel) and rarely to others (such as 

copper). 
178

Table 18: Examples of causes of leaks, development rate and prevention

Type of leak Cause Development Prevention

Forced rupture damage mechanical impact 

from external object

Immediate protect equipment against 

external impact, drop test

Pitting corrosion, crevice 

corrosion, galvanic 

corrosion

Presence of chloride, 

dissimilar metals 

Slow, 

gradual

Avoid combinations, 

contaminants

microbiologically-induced 

corrosion

Presence of certain 

microorganisms

Slow, 

gradual

Prevent occurrence of stagnant 

moisture, protection of surfaces

Erosion-corrosion High velocity flow, 

containing particulates

Slow, 

gradual

Reduce velocities and 

particulates

Stress-corrosion 

cracking

Strain and tensile 

stresses within pipe, 

pressure/temperature 

transients, ammonia 

and water presence

Gradual g

immediate

Prevent combination of conditions

Fatigue cracking Excessive fork hardening from due to 

vibration rate

Gradual g

immediate

Good pipe design, vibration 

testing

Thermal fatigue Thermal stratification, 

cycling, stripping

Gradual g

immediate

Good pipe design, vibration 

testing

Pressure rupture, burst Excessive internal 

pressure

Gradual g

immediate

Good piping design, selection 

of pipe material, consideration 

of temperature fluctuations

Loosening of fitting Vibration, poorly made 

connection

Immediate Pressure limiting devices, 

proper design pressure

Softening of elastomeric 

seal

Chemical reaction with 

materials, high absorptivity

Slow, gradual 

to medium 

rate

No mechanical joints or well 

made mechanical joints, no 

screw fittings

Fretting Repetitive rubbing of 

surface

Slow, gradual Proper material compatibility 

checks

Liquid hammer Pressure wave from 

instantaneous valve 

closing

Slow, gradual Avoid contact between hard 

surfaces
179

All of the data can be collated in order to develop a distribution of different leak sizes for a particular set 

of equipment. Thus, for each nominal incremental leak size, the frequency and consequence may be 

evaluated. An example of such a data-set is provided in Figure 50. 

Figure 50: Example of a leak size distribution for a set of systems, where large leaks are very infrequent 

and small leaks are much more frequent 

Figure 51: Example of refrigerant leak holes due to corrosion

Another means of evaluating the size of a leak is to enclose the leaking component within an air-tight 

container. Into the leaking component is fed a supply of gas, and then the gas concentration within the 

container can be measured and the additional mass of the vessel after a certain period of time. By using a 

mass balance, the leak rate for a given pressure differential (and particular gas) can be estimated. An 

example of the type of set-up that may be used is illustrated in Figure 52.

0,0000001 

0,00001 

0,001 

0,1 

0,001 0,01 0,1 1 10 

Leak frequency (1/yr) . 

Leak mass flow rate (g/s) 

Leak frequency (1/yr)

Leak mass flow rate (g/s)

0,001 0,01 0,1 1 10

0,1

0,001

0,00001

0,0000001
180

Figure 52: Option for measuring release rate from a leaking component, joint or other element

Also as a part of the leak evaluation process, it is useful to assess exactly how much refrigerant remains 

in the system after a leak has ceased, i.e., how much refrigerant will actually leak out, rather than the 

quantity that is charged into the system. Some refrigerant usually remains in the system, sometimes 

absorbed within the compressor oil, and also how much is retained in the internal volume of the system 

under atmospheric pressure. This may be done experimentally, by weighing the system before and after a 

leak, or estimated by calculation from the internal volume and the mass and solubility of the refrigerant 

within the compressor oil. 

The quantity of refrigerant retained can typically vary from 5% to 50%, depending upon the size and 

geometry of the system, the operating mode and operating conditions, type of oil, and so on.

5.8.6 Dispersion of refrigerant releases 

Once a leak has occurred, the risk becomes a function of the behaviour of the gas with respect to the 

local environment. In particular, the release may originate from a refrigerant containing part located 

external to the confines of the refrigerating equipment, or from a part located within the housing. If the 

release occurs within the housing, then it may be rapidly transferred out of the equipment, or it may 

accumulate within. For example, if the conditions are such that the refrigerant exiting the leak hole is 

immediately mixed with the surrounding air within a very large space, then the amount of flammable 

material will be small, and unlikely to come into contact with a source of ignition. Conversely, if the 

refrigerant leak enters a relatively small space with minimal air movement, then due to its density being 

greater than that of air, it may accumulate and exist for a longer period of time within its flammable 

limits. The larger this “cloud” and the longer it exists for, then the greater the likelihood that it may 

come into contact with an active source of ignition.

Figure 53 and Figure 54 illustrate this concept of the formation of a flammable region for a release into a 

room, and into equipment housing (or even machinery room), respectively; the flammable region is the 

volume of the gas/air mixture that is in a concentration between the LFL and UFL.
181

In order to estimate the amount and concentrations of released refrigerant that exists within its flammable range, it is important to be able to characterise how the release disperses. One means of evaluating 

the complex dispersion process is by observing the development of floor concentrations. Understanding 

the various physical parameters that affect the dispersion of a release is important for both carrying out a 

risk analysis and also for developing design features of the RAC equipment. Thus, the following elaborates on some selected aspects affecting dispersion of a release. (Appendix 5 contains a set of correlations 

for calculating average floor concentrations under a range of conditions.)

Release rate

Normally, that that a higher release flow rate produces higher concentrations, since a greater quantity is 

dumped in a shorter time, giving it less time to disperse before the region is flushed with more gas. For a 

finite charge, the mass flow rate of the refrigerant (assumed to be constant) dictates the release time, 

which implies that the shortest time for the total charge to be leaked will produce higher concentrations. 

The minimum release time assumes a complete shearing of a refrigerant pipe, such that the compressor 

pumps out al the refrigerant within a matter of minutes. The actual time for this to occur depends of 

course upon the charge size, compressor displacement, component dimensions and so on. However, 

under real conditions a loss of refrigerant is likely to stop the compressor, thus slowing release rate, 

combined with dissolution from compressor oil, reduction of internal pressure due to rapid vaporisation 

of refrigerant, internal restrictions such as expansion devices and other valves, and so on. Experiments 

reveal that for smaller systems the fastest possible leak time is around three or so minutes, and longer for 

larger systems. In reality, leaks occur over a wide range of durations, from minutes to days to weeks and 

longer. 

Figure 55 shows the maximum floor concentration for a release of R290 for the complete charge of 

refrigerant to be released over a range of different durations. In general it is seen that the longer the 

release time (or lower the mass flow rate) the lower the maximum floor concentration will be. Of course, 

most causes of leaks, a release with a high mass flow is unlikely to occur immediately; most leaks start 

small and evolve into larger ones.

Figure 53: Illustration of the flammable region 

following a refrigerant leak from an evaporator 

into a room

Figure 54: Illustration of the flammable region 

following a refrigerant leak within equipment 

housing and gradual escape of mixture
182

Release velocity

Typically, a higher leak velocity improves the mixing of the released refrigerant within a space. Generally, 

a leak from a refrigeration circuit will be at very high velocity due to the large pressure difference. 

However, in some cases the leak may impinge on the inside surface of an enclosure causing the release 

into the room itself to have negligible momentum. Examples of this include releases inside a refrigerated 

compartment or within AHU casing. 

Releases may be in vapour phase or mixed phase (once it expands into the atmospheric pressure and 

temperature). Vapour-phase releases are considered to be the worse case since two-phase releases are 

expected to produce more favourable mixing since the liquid rapidly flashes off to create a large amount 

of mixing within the room. 

Release direction, height and location

The orientation of a release strongly influences floor concentrations. A downward direction leads to 

higher floor concentrations, whilst upward directed releases produce much lower concentrations. In the 

case of very low velocity releases though, the effect of orientation becomes minor since the momentum 

of the plume is small compared to buoyancy forces. 

The mean concentration within a plume of released gas also reduces with distance from the source, 

which is reflected by floor concentrations. Figure 56 shows how sensitive maximum floor concentrations 

are to the release height. Given that refrigerant-containing parts of RAC equipment vary widely in their 

height, it is important to consider the effect of leaks from a variety of heights. 

Room size

Generally the size of the room area and its volume will affect the concentrations arising from a release. 

As would be expected, for a given release mass, the floor concentrations will reduce as the room size gets 

larger, as shown in Figure 57. However, if a mass that is proportional to the room volume is released (for 

example, based on a fixed mass per m3

 of room volume) then the maximum floor concentration can be 

higher, as shown in Figure 58. This is because of the additional time it required for the refrigerant to 

move across the room. It is also noted that if there is some airflow within the room, the rate of increase 

in floor concentration with larger room size because diminished. In terms of room geometry, several 

studies have found that room shape and ceiling height had negligible influence on floor concentrations 

particularly in a still environment. 

0 

0,01 

0,02 

0,03 

0,04 

0,05 

0,06 

0 5 10 15 20 25 30 

Max mean floor conc (kg/m3) . 

Time to release entire charge (mins) 

0.2 kg 

0.4 kg 

0.6 kg 

LFL 

0 

0,01 

0,02 

0,03 

0,04 

0,05 

0,06 

0,0 0,5 1,0 1,5 2,0 2,5 

Max mean floor conc (kg/m3) . 

Release height (m) 

300 g in 3 mins 

300 g in 7 mins 

300 g in 14 mins 

LFL 

Figure 55: The maximum floor concentration 

following the release of a given quantity of R290 

into a 25 m2 room over different release times

Figure 56: The maximum floor concentration following the release of a 300 g into a 25 m2

 room for a 

range of release heights for different release times
183

Floor surface and obstacles

Normally, a courser floor texture will result in poorer mixing and thus higher concentrations because of 

the greater frictional resistance to the gas cloud moving across the surface. Thus thick carpets tend to be 

more hazardous than smooth tiles, for example. In terms of obstacles within the room, it is known that 

obstacles do not generally inhibit mixing, except in certain occasions where channels are created or when 

there is a barrier at floor level.

Air movement

Air movement has a major influence on dispersion of a release. Firstly, movement of air is generated by 

the falling of the gas within the room, and may also be produced by infiltration, forced airflow and 

thermal sources. Since RAC equipment often utilises an integral fan to discharge air from the evaporator 

or condenser into the room, it is important to consider its effect on dispersion, as well as exhaust or other 

ventilation sources. 

Infiltration rates within rooms are known to vary widely depending upon the construction of the 

building and the external weather conditions, typically varying from as low as 0.5 h-1 air changes to over 

10 h-1 air changes. Measurements have shown that even the smaller infiltration rates of less than 0.5 h-1

influence floor concentrations. Thermally induced convection from warm surfaces can produce significant air mixing, thus lowering floor concentrations. Such thermal sources may include heat transfer 

through walls, generation of heat from human (or animal) occupants, from radiators or similar heaters 

and electrical appliances. 

The air speed in the room has a strong influence on the mixing of a release in a room. Generally, the 

higher the airspeed the lower the concentrations (assuming all other parameters are constant). Also, it is 

known that once some critical air speed is achieved, then essentially homogenous mixing will occur, that 

is no stratification of the refrigerant release will be present. This is illustrated in Figure 59 for two 

different release quantities. In terms of airflow from RAC units, the discharge velocity of the air duct 

influences the room air speed. Figure 60 shows how a smaller duct area produces better mixing, despite 

the same airflow rate. 

Figure 57: Maximum floor concentration for a 0.5 kg 

release into a room within 7 minutes under still 

conditions

Figure 58: Maximum floor concentration for a 

release mass corresponding to 8 g/m3 into a room 

within 7 minutes, with and without airflow

0 

0,01 

0,02 

0,03 

0,04 

0,05 

0,06 

0 10 20 30 40 50 60 70 80 

Max mean floor conc (kg/m3) . 

Room area (m2) 

0.5 kg in 3 min 

0.5 kg in 7 min 

0.5 kg in 14 min 

LFL 

60% of LFL 10% of LFL 

0 

0,01 

0,02 

0,03 

0,04 

0,05 

0,06 

0 20 40 60 80 

Max mean floor conc (kg/m3) . 

Room area (m2) 

no airflow 

125 m3/hr 

250 m3/hr 

LFL 
184

The positioning of the source of airflow discharge source, such as the fan or the duct, can also influence 

the mixing of the refrigerant. Further, the height of the ventilation inlet and outlet are critical to mixing, 

particularly with respect to the position of the release source. Since on RAC equipment, the fan height 

can vary widely with equipment type, it is considered an important variable. Figure 61 illustrates the 

influence of height variation of floor concentration – when there is no airflow, the closer the release to 

the floor, the higher the concentration. However, if there is airflow, and the duct discharge is at about 

the same position at the release, the height has little influence on the concentration. If the duct height is 

fixed at a high level, the presence of airflow causes the floor concentration to be reduced, but it continues 

to increase as the release position approaches the floor. 

Similar trends apply to the direction of the airflow discharge; whilst most condensing units discharge air 

in a single direction, many duct outlets have a multi-directional discharge vent. As with the height of the 

discharge, the airflow direction relative to the direction of the release is a significant factor in the amount 

of mixing. 

Refrigerant type

Several HCs are likely to be used in refrigeration and air conditioning systems: R290, R600a and 

R1270, and mixtures thereof. Each has a slightly different density and therefore they will exhibit slightly 

different dispersion characteristics. Figure 62 compares the floor concentrations for these three refrigerants over a range of airflow rates. It is seen that whilst R290 and R1270 behave similarly, R600a tends to 

give notably higher concentrations. The density of R600a vapour at atmospheric pressure and temperature is about 40% higher than R290 and R1270, and therefore has a tendency to sink towards the 

ground faster and is less susceptible to the effects of surrounding air movement.

Releases into small enclosures

A slightly different situation is that illustrated in Figure 54, where a leak occurs within the housing of 

the refrigerating equipment. Due to the level of confinement, only a relatively small quantity of refrigerant can escape from the enclosure and a flammable concentration rapidly develops, and thereon remains 

for a long duration. The small volume of the enclosure encourages homogenous mixing of the refrigerant 

and air mixture into a high concentration, thus with the continual ingress of air, it is possible that a 

flammable concentration could always be present. With this type of situation it is important to ensure 

that there is as free a flow of air through the enclosure as possible, which may of course require mechanical ventilation. In fact, this situation is also comparable to the case of a machinery room, where rather 

large quantitative of refrigerants (in relation to the size of the room) may be released into the space.

Figure 59: Effect of mean room air speed, of a 

release into a 25 m2 room; at a sufficiently high 

air speed, the maximum concentration is the same 

as the mean room concentration

Figure 60: Effect of air outlet duct area on floor 

concentration of a 0.5 kg release in 7 min into a 

25 m2 room; the smaller duct area produces a 

higher velocity the creates better mixing

0 

0,01 

0,02 

0,03 

0,04 

0,05 

0,06 

0,00 0,05 0,10 0,15 0,20 

Max mean floor conc (kg/m3) . 

Mean room air speed (m/s) 

0.6 kg, av conc 12 g/m3 

0.2 kg, av conc 4 g/m3 

LFL 

0 

0,01 

0,02 

0,03 

0,04 

0,05 

0,06 

0,00 0,10 0,20 0,30 

Max mean floor conc (kg/m3) . 

Airflow rate (m3/s) 

0.025 m2 duct area 

0.100 m2 duct area 

LFL 
185

5.8.7 Consequences of ignition

Once the refrigerant has leaked from the system and has formed a flammable mixture, it is important to 

understand the possible consequences if it is ignited. The consequence may be perceived as a change in 

the distribution of the energy that is released after the combustion process. The flow chart in Figure 63 

illustrates the types of processes that are undergone to result in a consequence. 

Figure 63: Combustion process leading to consequences

Consequences of ignition have two categories: a primary consequence which describes the events that 

occur as a direct result of ignition (e.g., pressure rise and thermal radiation) and a secondary consequence, which are the events that are caused by the primary consequence (e.g., damage to buildings and 

secondary fires).

The severity of the consequences is partly related to the initial quantity of heat released in the combustion process, but it is also affected by the environment under which the combustion process occurs. For 

example, in the case of R290, ignition of a stoichiometric mixture will result in a flame temperature of 

around 2000°C (i.e., approaching the adiabatic flame temperature, Table 24). If this occurs inside and 

the nearby surroundings are fairly combustible a secondary fire could occur, whereas if this occurs 

outside on non-combustive materials, the secondary consequence could be minimal. 

Figure 61: Effect of release height in relation to 

air discharge height, when the duct is at the same 

height as the release, and when the duct height 

is fixed

Figure 62: Variation in floor concentration for 

different HC refrigerants, over a range of air 

flow rates

0 

0,01 

0,02 

0,03 

0,04 

0,05 

0,06 

0,0 0,5 1,0 1,5 2,0 2,5 

Max mean floor conc (kg/m3) . 

Release height (m) 

duct = release height 

duct = 2.2 m 

LFL 

0 

0,01 

0,02 

0,03 

0,04 

0,05 

0,06 

0,00 0,05 0,10 0,15 0,20 

Max mean floor conc (kg/m3) . 

Airflow rate (m3/s) 

R600a 

R290 

R1270 

LFL 

5.8.7 Consequences of ignition 

Once the refrigerant has leaked from the system and has formed a flammable mixture, it is 

important to understand the possible consequences if it is ignited. The consequence may be 

perceived as a change in the distribution of the energy that is released after the combustion 

process. The flow chart in Figure 63 illustrates the types of processes that are undergone to result 

in a consequence. 

Figure 63: Combustion process leading to consequences 

Consequences of ignition have two categories: a primary consequence which describes the events 

that occur as a direct result of ignition (e.g., pressure rise and thermal radiation) and a secondary 

consequence, which are the events that are caused by the primary consequence (e.g., damage to 

buildings and secondary fires). 

The severity of the consequences is partly related to the initial quantity of heat released in the 

combustion process, but it is also affected by the environment under which the combustion 

process occurs. For example, in the case of R290, ignition of a stoichiometric mixture will result in 

a flame temperature of around 2000°C (i.e., approaching the adiabatic flame temperature, Table 

22). If this occurs inside and the nearby surroundings are fairly combustible a secondary fire could 

occur, whereas if this occurs outside on non-combustive materials, the secondary consequence 

could be minimal. 
186

The two forms of consequences that should be addressed are thermal intensity (I), which can be used to 

quantify degrees of burns to people (or likelihood of secondary fire), and overpressure (Δρ°) that causes 

damage to building structure and injury to people. An outcome of large and/or Δρ° includes damage to 

buildings, their contents, injury to people and fatalities. (With regards to an ignited jet or plume, its 

velocity is generally greater than flame speed and so burning is unlikely to be sustained.) 

The necessary I for flashover (that is, leading to a secondary fire) varies considerably with construction 

and furniture materials. Data showed flashover to occur over a range of I = 125 – 4100 s (kW m-2)4/3, 

including different foam insulation, wood and gypsum based materials. Other easily combustible materials such as loose paper or hair may ignite at even lower I.

Thermal radiation 

When a flammable substance burns, the heat energy is partially given off as thermal radiation. A “dose” 

of thermal radiation may be sufficient to cause burns to individuals nearby. The severity of burns is a 

function of heat flux and its duration, and this dose is termed thermal intensity, and it is a function of 

the heat flux from the combustion and the duration that the heat source is present (say, the burning 

time). The heat flux radiated onto an occupant (qocc, in kW m-2) is a function of the total heat released 

(the product of the mass of flammable material and its heat of combustion), the burning time, and an 

incidence ratio which is influenced by the size and shape of the flammable volume.

At around Iocc= 115 s (kW m-2)4/3 pain will be felt on exposed skin, becoming more severe with higher 

Iocc. Above Iocc = 1050 s (kW m--2)4/3 fatalities are expected and death is almost guaranteed at 6500 s

(kW m-2)4/3. 

Overpressure 

When a flammable mixture is ignited, the exothermic reaction raises the temperature of the combustion 

products, translating to an increase in pressure and/or volume. Under ideal conditions, where ignition is 

at the centre of a spherical stoichiometric mixture, the maximum pressure or volume can be reliably 

determined from the gas law. Based on the initial (ambient) temperature of the flammable volume, and 

the maximum adiabatic flame temperature, the maximum pressure that can be reached is approximately 

seven times the atmospheric pressure, assuming a confined (fixed) volume that is completely filled with 

the mixture. Conversely, if the flammable mixture were in an unconfined volume (i.e., constant pressure) 

its volume after combustion would be approximately seven times the initial volume of the flammable 

mixture. For most situations under consideration, the flammable material is within a partially confined 

space and only occupies part of that space. This implies both a pressure rise, and a volumetric change of 

the burning mixture within the room. As a result the overpressure within the room (Δρ°

Rm) will be less 

than seven times atmospheric pressure.

The pressure and/or volume of a flammable mixture increase exponentially following ignition until a 

maximum pressure (ρmax) is reached, and that development of Δρ at time (t) after ignition follows the 

“cube-law”. The rate of the burning front under ideal conditions is at a speed that corresponds to the 

laminar burning speed (about 0.4 m/s for HCs, see Table 24). However, the influence of room geometry, 

obstacles and air movement creates turbulence which further accelerates the flame front. Based on 

experiments in fairly empty rooms, this corresponds to an increase of about three times the laminar 

burning speed. 

Most rooms and enclosures are not completely sealed, and most occupied spaces have paths in the room 

fabric through which developed pressure will escape. As Δρ°

Rm rises, material may be vented from the 

room, and this occurs in two stages. Initially, any openings such as gaps in the room fabric, ventilation 

ducts, etc, allows the higher pressure gas to escape from the room. Secondly, certain barriers that com-
187

prise the room construction may eventually give way at a given Δρ°

Rm, thereby enlarging the venting 

area. In both cases, the exhausted material results in a lower rate of pressure rise. The overpressure at 

which panels, windows and other items are blown out, is a function of their mass (inertia), size and the 

strength of fixings. 

Four examples of Δρ°

Rm development over time are given in Figure 64, which were based on a flammable 

R290 mixture in a 40 m2

 × 3 m room. By far the greatest Δρ°

Rm is for a fully confined room that is 

entirely filled (120 m3

) with a stoichiometric mixture. By introducing a vent panel (equivalent to 5% 

or the total wall area), there is a major reduction in Δρ°

Rm as the excess pressure is rapidly exhausted 

(noting also that the burn time is reduced because some of the flammable material was vented before it 

was burned). A more realistic situation is where the room contains a flammable layer of 0.5 m deep (or 

24 m3

 at a concentration between LFL and stoichiometric), and when ignited produces Δρ°

Rm proportionally lower than the completely flammable room. Again, by introducing a vent, Δρ°

Rm is further 

reduced.

Figure 65 provides examples of the overpressure evolving from different design features of equipment 

housing. It is assumed that refrigerant has leaked into a rigid metal enclosure that is half filled with a 

stoichiometric gas/air mixture (this may also be analogous to a machinery room). Simulations for four 

situations are presented:

• Housing with 0.5% of the enclosure wall area open

• Housing with 10% of the enclosure wall area open

• Housing with a steel panel covering 15% of the wall area

• Housing with a plastic panel covering 15% of the wall area

It can be seen that with a very small opening, the effects of ignition could result in a significant overpressure (nearly 200 kPa), with the possibility of the resulting shockwave causing notable damage to property. However, if the opening is significantly larger (say 10% of the enclosure surface area, in this case) 

then the rising pressure is rapidly vented, and the resulting overpressure is some 100 times lower than in 

the previous case. The use of detachable panels has a similar effect, although there tends to be an initial 

peak that represents the blowing-off from its fixings. Nevertheless, the resulting overpressure is massively 

reduced compared to the small vent opening, and it would be highly unlikely to result in secondary 

Figure 64: Examples of room overpressure development under different situationsFigure 65: Examples of compartment overpressure 

development with different designs
188

damage. This example emphasises the importance of appropriate design of equipment housing. 

If there is overpressure within an enclosure that escapes, a shock-wave will travel outwards. The pressure 

wave will have an exponential decay away from source, and the rate of decay is mainly a function of 

source overpressure only. However, within enclosed spaces, shockwave will be reflected (but dampened), 

but nevertheless, it may still damage building structure. 

To interpret the severity, any Δρ°

Rm below about 3 kPa is unlikely to cause any physical damage to 

persons or property. Persons exposed to overpressure (alone) above about 250 kPa would be begin to 

suffer fatalities. As Δρ°

Rm approaches 450 kPa, death is almost guaranteed. 
189

6.1 TECHNICIAN ACTIVITIES AND REFRIGERANT HANDLING 

6.1.1 Introduction

This section mainly deals with the issues faced by technicians that are working on systems and equipment that use HC refrigerants. Primarily this involves refrigerant handling aspects, but also checking 

that the area and the equipment are safe to use HCs and that refrigerant containers are handled properly. 

Studies on flammable refrigerants have demonstrated that the risk of fire or explosions is higher when 

systems are being worked on, compared to when they are operating normally. Due the fact that the 

possibility of a release of refrigerant and the presence of potential sources of ignition is greater, the risk of 

ignition is typically 100 – 1,000 times greater than when the equipment is not subject to human interference. This highlights the importance of having only competent technicians working on such systems, 

and that it is essential to follow proper safe working procedures. 

The main stages of the RAC equipment life that require handling of refrigerants include the following:

• Assembly and installation of systems and equipment

• Carrying out routine maintenance on systems and equipment

• Carrying out servicing and repair activities to systems and equipment

• Decommissioning, dismantling and disposal of systems and equipment

During these stages, a variety of specific activities are normally carried out that involve either refrigerant 

handling directly, or the possibility of contact with an emission of refrigerant. These include, for example, refrigerant recovery or venting, evacuation, leak checking and gas detection, charging and general 

handling of cylinders. On the other hand, there are also certain activities that do not relate directly to 

the refrigerant, but are equally important since they also contribute to the safety of the system in the 

event of an accidental release or provision of warnings to others, such as proper sealing of systems, 

repairs to electrical components and marking of systems.

Whilst the requirements detailed forthwith may seem considerably more onerous than when non-HC 

refrigerants are used, in actual fact, the majority of the requirements are identical for both flammable 

and non-flammable refrigerants. However, it is the importance of following the rules precisely for safety 

purposes that is the primary difference. Therefore, in addition to having specific knowledge related to 

HC refrigerants, technicians must also be knowledgeable in RAC systems technology in general and 

should be fully competent in the safe handling of non-flammable refrigerants. 

Whatever the type of refrigerant, some common hazards apply to all refrigerants, such as:

• Gases and liquid under pressure, when released under atmospheric conditions can cause freeze burn 

(similar to frost bite) if it comes into contact with skin. Therefore, proper personal protection (such as 

goggles, gloves and full body clothing) must be worn. If the skin does come into contact with refrigerant under these conditions, treat the affected area by bathing the area with cold water as the first aid 

followed by consultation with a medical professional. 

PART 6: WORKING ON SYSTEMS AND EQUIPMENT
190

• Released refrigerant will displace air in the lower part of the room, therefore posing the threat of 

asphyxiation and causing suffocation to occupants or other toxic effects. Therefore, ventilation is 

required and the technician must be aware of the necessary actions to take in this event. In case of 

such accidents, the person must be removed to an uncontaminated area and kept warm and still, and if 

required, given artificial respiration or oxygen and seek medical help if needed.

Furthermore, it is difficult to anticipate all possibilities and situations, so it is essential to be aware that 

the requirements here are not exhaustive, and are intended as a general guide only. Additional precautions may be appropriate dependent upon the particular equipment and conditions. 

Whilst it is the technicians that will be carrying out the work on the system, and handling the refrigerant, the employer and the owner and operator of the facilities have the overriding responsibilities. In 

most countries, this is a legal responsibility. In particular, the employer/owner/operator must be responsible for the following:

• Ensuring that all equipment and materials for use by the technician are fit for purpose and are in an 

acceptable condition

• Ensuring satisfactory working conditions and, in particular, adequate lighting, good accessibility, etc

• Ensuring that working procedures/instructions are available for each process to be undertaken by the 

technician

• Ensuring that the person sent to carry out a particular activity is component to do so, and if not, then 

a supervisor of the required level of competence is always present

• Ensuring that a general strategy is in place so that correct working practices are employed

Lastly, all parties – technicians as well as the employer, facilities owner and operators – must put in place 

a system to record all the actions that have taken place, and in particular record any accidents, incidents 

and near misses that have occurred during the working activities. In the event that some such event does 

occur, it should be investigated and measures put in place to prevent it from reoccurring (see Part 1.3 

and Part 2). In the case that there is a problem with the RAC equipment, the fault or problem must be 

reported to the supplier or manufacturer so that the problems can be rectified accordingly. All activities 

associated with handling the equipment should be logged on data-sheets (see Appendix 9 for an example). 

6.1.2 Risk assessment

Whenever someone is working on a system that contains flammable refrigerants, the necessary precautions must be taken. The identification of those precautions is usually obtained through the process of 

risk assessment. In principle, an ignition event due to HC refrigerants can occur only when three 

essential preconditions simultaneously occur:

• First is the refrigerant release

• Second is the occurrence of a flammable mixture of HC and air

• Third is the presence of an active ignition source of a certain energy level or temperature at the same 

location and at the same time

The combination of the above three occurrences has to be prevented. An analysis of each working 

activity must be carried out. 

The employer and/or facilities owner and/or operator (or its representative, which may be authority 

delegated to a sufficiently competent technician) has to make a suitable and sufficient assessment of the 

risks to employees arising from the flammable substance and to eliminate or reduce the risk, as far as is 

reasonably practicable. This is achieved by adopting a process which either eliminates or reduces the risk. 

The risk assessment procedure must consider:
191

• The hazardous properties of individual substances and the hazardous properties of substances when 

used in combination and the circumstances of the work

• The individuals that may be at risk of harm

• The likelihood that an explosive atmosphere will occur and its persistence

• The likelihood that ignition sources will be present and become active and effective

• The scale of the anticipated effects of a fire or an explosion

Based on these considerations, measures must be devised and applied, consistent with the risk assessment 

and appropriate to the nature of the activity or operation, to the following (in order of priority):

• Reduce the quantity of dangerous substances to a minimum

• Avoid or minimise the release of a flammable substance

• Control the release of a dangerous substance at source

• Prevent the formation of a flammable atmosphere, including the application of appropriate ventilation

• Ensure that any release of a flammable substance which might give rise to risk is suitably rendered safe

• Avoid ignition sources

• Reduce to a minimum of the number of workers and eliminate the members of public that may be 

exposed

• Avoid propagation of fire or explosion

• Provide fire and explosion protection methods

• Provide suitable personal protective equipment

The risk assessment must be regularly reviewed and make any revisions that are found to be necessary. 

Before a workplace containing places where a flammable mixture could occur can be used for the first 

time, the employer and/or facilities owner and/or operator has to ensure that its overall fire and explosion safety is verified by a competent person. All risk assessments must be documented.

SAFE WORKING CARDS

Companies should provide their employees with laminated cards to assist their working safety 

on site. These laminated cards should include a site safety check list and a basic risk assessment procedure. They should be hard-wearing and be easy and convenient for the technicians 

to use, comprising the most important aspects to remember. If the technicians are likely to 

encounter a range of different types of equipment, it may be pertinent to develop such cards 

for each specific type of system or environment. 
192

Figure 66: Identification of activities that may involve and emission of refrigerant
193

Figure 66 shows typical sequence of activities that technicians may carry out when working on a system 

for the purposes of installation, maintenance, servicing and dismantling. During any of these activities, 

the technicians may have to carry out refrigerant handling activities, or may come into contact with an 

emission of refrigerant for some reason. The majority of such situations are identified within 

Figure 66; but of course, many other circumstances arise that also demand additional considerations. 

The following sections therefore provide some guidance of the important considerations for these 

activities in particular, so that appropriate risk assessment and subsequent working instructions can be 

developed. In addition, guidance is also provided for the other activities, i.e., where the presence of 

flammable refrigerant is not anticipated, but which must be addressed since they also contribute to the 

overall safety of the site-work and to the longer-term safety of the equipment when technicians are not 

present.

6.1.3 General precautions for working

Before carrying out any work on a refrigerating system or associated equipment, it is essential to ensure 

that the immediate area is suitable for working safely, and the appropriate precautions are in place. In 

particular, prior to beginning work on systems containing HC refrigerants, safety checks are necessary to 

ensure that the risk of ignition is minimised.

The following precautions should be taken before working on the refrigerant circuit:

• All staff and others working in the local area must be instructed on the nature of the work being 

carried out

• The area around the workspace must be sectioned off

• Obtain permit for hot work (if required)

• Working within confined spaces should be avoided

• No flammable materials are stored in the work area 

• No ignition sources are present anywhere in the work area

• Suitable fire extinguishing equipment (CO2 or dry-powder type) is available within the immediate 

area

• The work area is properly ventilated before working on the refrigerant circuit or before brazing or 

handling electrics

WORKING AREA GAS DETECTION

Whilst technicians are working on systems, it can be advisable to make use of a portable 

gas detector. Such a detector can be clipped to clothing or placed on the floor within the 

working area. It should be switched on for the duration of the work, and set to alarm at 

15% of the LFL, to warn that flammable concentration may be nearby. In this way, technicians 

can be alerted whenever an inadvertent release of flammable refrigerant occurs, and can 

immediately act upon the relevant emergency procedures.
194

• Ventilation should safely disperse any released refrigerant and preferably expel it externally to the 

outside

• Suitable flammable gas detectors are present and operating to warn workers of a dangerous concentration of refrigerants and that the gas detection equipment being used is non-sparking, adequately sealed 

or intrinsically safe

• All maintenance staff have been instructed

• Erect appropriate signage, including “no smoking” and “do not enter the area” signs

• All appropriate and necessary tools and equipment are available

Only work with the appropriate type of nitrogen: oxygen-free dry nitrogen (OFDN). The presence of 

oxygen can introduce a flammability risk (and the presence of moisture can be damaging to the reliability and operation of the refrigerating system). In some countries, carbon dioxide (CO2) may be more 

readily accessible to technicians than nitrogen; this is an acceptable alternative, provided that it meets 

the same requirements in terms of no oxygen and no moisture, i.e., oxygen-free dry carbon dioxide. 

The technician should always carefully read the installation and/or service manual that is provided by 

the manufacturer, so that they are aware of any special particular requirements associated with the 

equipment under consideration. New or replacement components should be according to the manufacturers specifications. If in doubt consult the manufacturer’s technical department for assistance.

Other activities required to be carried out on the system or equipment that require the assistance of other 

skilled personnel, should only be carried out under the supervision of the person competent in the use of 

flammable refrigerants.

If the installation permits, it is recommended that the equipment is removed from its existing position to 

a controlled workshop environment where work can usually be conducted in a more controlled and thus 

safer manner.

Some initial issues must also be addressed prior to working on a particular system or piece of equipment 

before carrying out any work:

• It is essential that the technician is completely familiar with the equipment and all its detail

• The technician must be familiar with the equipments purpose and operation

• The equipment should, whenever possible, be isolated from the electricity supply

• Ensure that all refrigerant handling and mechanical handling equipment is available

• All necessary personal protective equipment is available and being used correctly

TEMPORARY FLAMMABLE ZONES

When working on systems using flammable refrigerants, the 

technician should consider certain locations as “temporary flammable zones”. These are normally regions where at least some 

emission of refrigerant is anticipated to occur during the normal 

working procedures, such as recovery, charging, and so on; typically where hoses may be connected or disconnected. In anticipation of the maximum quantity of refrigerant that may be released 

during such a procedure (such as disconnecting a hose whilst it 

is full of liquid refrigerant), the minimum distance from this point 

that should be considered as a temporary flammable zone, is 

around half a metre in all directions. 
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6.1.4 Accessing a refrigerant circuit

Ideally when accessing a system, either to add refrigerant or remove it, service valves should be employed. 

If service valves are not present, then a shraeder type valve should be selected. For smaller systems there 

may not be any direct means of accessing the system, in which case two options are available:

• Application of a piercing tap valve

• Use of piercing pliers

If either of these methods is applied, then it is essential to select the correct diameter fitting for the pipe, 

otherwise it is highly likely that the refrigerant will not be contained and a large release will occur. It is 

also important to note that neither of these methods is considered to be a permanent access point to the 

system. Therefore, after all the refrigerant has been removed and the system flushed with OFDN, the 

pliers or piercing valve must be removed, and replaced with a permanent connection. 

Regardless of the means of accessing the system, any method will result in some emission of refrigerant 

and therefore the appropriate precautions should be put in place to minimise the size of the emissions 

and eliminate any potential sources of ignition.

Under no circumstances must the system be broken into it contains any flammable refrigerant or any 

other gas under pressure, by means of cutting or breaking pipework. 

A number of other aspects must be considered when gaining access to a system:

• If it is necessary to break into a system, especially to change parts or to carry out brazing, all of the 

refrigerant must be recovered from the system, using the appropriate procedures detailed below

• Although it may be possible to pump-down a system and isolate refrigerant within parts of the system 

that is not being worked on, it is generally preferable to remove the entire refrigerant charge in case of 

unexpected failures

• If refrigerant has been removed, the system must be flushed with OFDN; although there will always 

be some residual HC within the system, the concentration in OFDN must be sufficiently low to render 

it non-flammable (thus, this process may need to be repeated several times)

• Flushing is achieved by breaking the vacuum in the system with OFDN and continuing to fill until 

the working pressure is achieved, then venting to atmosphere, and finally pulling down to a vacuum

• Before carrying out any further work, the area should be checked with an appropriate refrigerant 

detector prior to and during any hot work to make the technician aware of a potentially flammable 

atmosphere

• OFDN is then be purged through the system both before and during the brazing process; this operation is absolutely vital if brazing operations on the pipework are to take place

• Compressed air or oxygen must not be used for flushing or filling the system under any circumstances 

whatsoever

In all cases, only refrigerant handling and other service equipment designed for use with flammable 

refrigerants should be employed when working with HC refrigerants.

6.1.5 Refrigerant recovery

Prior to working on a system, it is necessary to remove the refrigerant from the system. Under most 

circumstances it is recommended to recover the refrigerant, as opposed to venting it. Conventional 

recovery procedures, as used for any other refrigerant, are equally applicable when dealing with HC 

refrigerants. However, special attention should be paid to certain aspects: 
196

• The recovery machine used must be suitable for use with flammable refrigerants, and in particular, it 

should not have any potential sources of ignition (the requirements are the same as those for a refrigerating system)

• The recovery cylinder must be suitable for the refrigerant used (specifically, in terms of the pressure 

rating and the compatibility of valve seals, etc)

When connecting hoses between the refrigeration system, manifold gauges, recovery machine, and 

recovery cylinder, ensure that the connections are secure and there are no potential sources of ignition 

nearby. Since it is good practice to purge the hoses, manifold and recovery machine prior to recovery to 

avoid the ingress of refrigerant, this should be done to minimise the emission of refrigerant but also 

whilst making sure that there is sufficient ventilation to dilute the release. 

Filling of the recovery cylinder should be done carefully by monitoring the mass of refrigerant added 

into the cylinder, thus the cylinder should be kept preferably on electronic balance throughout the entire 

procedure. Ensure that the cylinder does not overfill, that means the cylinder is not filled to more than 

80% of its volume with liquid refrigerant. Similarly, the discharge pressure should also be monitored to 

ensure that the maximum allowable pressure of the recovery cylinder is never exceeded. After recovery 

has been completed, the recovery cylinder should be labelled with the type and mass of refrigerant it now 

contains. 

RECOVERY CYLINDERS – BE CAREFUL!

When using a refrigerant recovery cylinder with HC refrigerants, it is essential to use it properly. Liquid HCs have less than half the density of fluorinated refrigerants, and therefore they 

take up more than twice the volume within a cylinder. If this is not considered when adding 

refrigerant to a recovery cylinder, there is a possibility of the recovery cylinder bursting – the 

consequences are severe! Any recovery cylinder should be filled to a maximum of 80% of its 

volume. If the refrigerant is R22, it must only be filled to 80%; if the refrigerant is R290, is 

must only be filled to 80%. However, in the case of R22, the mass may be 10 kg, whereas with 

R290 the mass may only be 4 kg. The figure below illustrates this concept. The essential thing 

to remember is that when the cylinder gets warmer (as it may do whilst standing outside in 

the direct sunlight, or sitting in a van being transported) the liquid expands and takes up more 

volume – this is also shown in the figure below. If the liquid expands too much, then the 

cylinder will be unable to withstand the pressure and will subsequently burst, certainly causing damage and injury. The maximum fill capacity of the cylinder can be estimated from: 

Max fill of HC (kg) = 0.4 × max fill of HFC or HCFC (kg)

For a more accurate calculation, the conversion factors in Table 20 can be used instead of 0.4.
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The recovery machine should be operated until the system pressure reaches a value of 0.3 bar, absolute 

(-0.7 bar gauge) or lower. Since HC refrigerants tends to be soluble in many types of oil, there may be a 

subsequent rise in pressure because of the slow desorption of refrigerant from the compressor oil. Thus, a 

second or third run of the recovery machine may be necessary. Once the refrigerant has been recovered 

to the appropriate system pressure, the system should be flushed with OFDN, to render the contents 

non-flammable.

General guidance on safe recovery procedures can be found in other publications.

6.1.6 Refrigerant venting

Venting may be carried out as an alternative to recovering the refrigerant. Because HC refrigerants have 

no ODP and negligible GWP, under certain circumstances it may be considered acceptable to vent the 

refrigerant. However, if this is to be considered, it should be done in accordance with the relevant national 

rules or regulations, if they permit. In particular, before venting a system, it would be necessary to:

• Ensure that legislation relating to waste material has been considered42 

• Ensure that environmental legislation has been considered

• Ensure that legislation addressing safety of hazardous substances is satisfied

Normally, venting is only carried out with systems that contain a small quantity of refrigerant, typically 

less than 150 g; larger quantities should be recovered. 

If venting is to be carried out, a set of special procedures is required to ensure that it is done safely, by 

following the general safety procedures discussed within this section, and through appropriate use of a 

suitable hose:

• Venting to inside a building is not permissible under any circumstances 

• Venting must not be to a public area, or where people are unaware of the procedure taking place

• The hose must be of sufficient length such that it will extend to at least 3 m beyond the outside of the 

building 

• The venting should only take place on the certainty that the refrigerant will not get blown back into 

any adjacent buildings, and that it will not migrate to a location below ground level

• The hose it made of material that is compatible for use with HC refrigerants and oil

• A device is used to raise the hose discharge at least 1 m above ground level and so that the discharge is 

pointed in an upwards direction (to assist with dilution)

• Ideally, there should be a type of rose on the end of the hose so that the vented refrigerant can discharge in different directions, with fairly small outlet orifices (so as to assist dilution) 

• Close to the inlet of the hose, an oil separating device is fitted to present the emission of refrigeration 

oil, so that it may be collected and disposed of properly following the venting procedure (a recovery 

cylinder may be used for this)

• There must be no sources of ignition near the hose discharge

• A flammable gas warning sign must be positioned close to the hose discharge

• The hose should be regularly checked to ensure that there are no holes or kinks in it, that could lead to 

leakage or blocking of the passage of flow

When carrying out the venting, the flow of refrigerant should be metered using manifold gauges to a 

low flow rate, so as to ensure the refrigerant is well diluted. Once the refrigerant has ceased flowing, the 

system must be flushed out with OFDN; if not, then the system should be pressurised with OFDN and 

the venting procedure carried out two or more times, to ensure that there is minimal HC refrigerant 

remaining inside the system.

42 Within the EU for example, there are conflicting views as to whether venting of such certain refrigerants is permissible.
198

A schematic diagram illustrating the vent hose is provided in Figure 67.

Figure 67: A diagram illustrating the positioning and design of the vent hose

6.1.7 Repair of leaks

It is of utmost importance to properly repair refrigerant leaks, as soon as they are discovered. If they 

cannot be repaired immediately, the refrigerant charge should be removed from the system until the 

point at which the leak can be properly repaired. A number of considerations are relevant when attempting to repair a leak:

• Repair the leak properly – this means, removing the refrigerant, examining the leak source, determining the reason for the leak and carrying out the proper course of action (it does not mean simply try to 

tighten the connection, or some other “quick-fix”)

• From examining the leak and subsequently determining the cause, try to identify and action relevant 

means to ensure that the leak will not reoccur 

• If the leak has occurred from a flared connection, if possible try to replace it with a brazed or similarly 

effective joint 

• Before embarking on the repair, ensure that the refrigerant had been removed and the system flushed 

with OFDN, especially if brazing is to take place

If system has been accessed using means such as piecing plies or line tap valves (due to there being an 

absence of appropriate screwed fittings for manifold gauge hoses), it is absolutely not acceptable to leave 

these devices attached to the system – they are highly prone to leakage and are easily mishandled. 

Instead, there exist various options for re-sealing a system, including fittings using brazing, press connections (e.g., “lok-ring”), Euro-flare connections and ferrule compression joints (e.g., “swagelok”) (see Part 

5.2). Whichever method is used, the pipe where the line tap valve or piercing pliers had been used must 

be replaced, and a proper charging point, such as Schrader valve or some other service port be fitted. 

Remember that whether a service prot of a Schrader valve is used, the cap must always be fitted. 

In general, the guidance on leak prevention should be followed when repairing a leak (see Part 5.2).
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6.1.8 Leak checking (for tightness testing)

Leak detection is an important activity to carry out when working on refrigeration systems, and an 

essential one for systems that use HC refrigerants. It is also vital to recognise that leak detection is not 

gas detection; gas detection is merely an aid to detecting leaks. It is noted that some methods used for 

leak detection do not necessarily rely on the detection of gas. 

During manufacturing or factory assembly of the system, the preferred method of leak detection is to 

pressurise the system with helium and use a highly sensitive helium gas detector to search for leaks. 

There is specific equipment available for carrying out these procedures. However, using pressurised 

helium detection is not convenient for site work. Therefore a number of other means for leak detection 

may be considered during on-site work:

• Bubble test: the system is pressurised to the nominal working pressure with OFDN (or the refrigerant, 

after charging for final leak testing), and every single joint, connection and component is and checked 

for bubbles using soapy water or other such fluids. This is the most commonly used method and is 

considered to be one of the most reliable.

• Holding pressure test: the system is pressurised to the nominal working pressure with OFDN, and the 

pressure is monitored over a period of time (at least 10 minutes) in order to check for a fall in pressure. 

This should be carried out within a constant temperature environment. However, this method is less 

accurate, it may not pick up very small leaks and the change in pressure may be a result in other factors 

such as internal pressure equalisation of mixing with oil.

• Gas detection: the system is charged with OFDN and a whiff of refrigerant to the nominal working 

pressure and refrigerant gas detectors are used to check every single joint, connection and component 

for the presence of refrigerant. (When using gas detection, see Part 6.1.4.) Often, this method is used 

alongside the bubble test to pinpoint the exact position of the leak. 

• Fluorescent dye: this requires that a particular dye be added to the system, which normally mixes with 

the oil. Thus, when leak occurs, the location of a leak can be traced, with the assistance of an ultraviolet lamp. Again, depending upon the size and location of the leak, this method often requires 

further identification of the exact leak position using the bubble test method.

• Ultrasonic sensor: the system is pressurised to as high a pressure as permissible (according to the 

system maximum operating pressure) with OFDN, and the sensing device is used to convert and 

amplify the sound of the leak such that the operator can detect it audibly. The effectiveness of this 

method is sensitive to the amount of noise in the surrounding area, and again requires the use of a 

bubble test to determine the precise position of the leak hole.

Upon identification of the leak, the appropriate procedures should be used to repair it. It is essential to 

be aware that systems may have more than one leak, so the system should be repeatedly checked, including positions of recently repaired leaks, to ensure that all the leaks have been found.

In general, frequent inspection of charge level and gas detection should be carried out, especially on 

larger systems. Whenever there is any indication that leakage has occurred, actions should be taken 

immediately to find and repair the leaks.

6.1.9 Strength (pressure) testing

Testing of the strength of the system using pressure is normally required after changes have been made 

to the system, including re-connecting parts of the system using brazing or mechanical joints, exchanging one or more components or making an addition to the assembly. The strength (pressure) test should 

be conducted in the same manner as with any other refrigerant. In summary:
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• Ensure all personnel are at a safe distance from any refrigerant containing parts

• Charge the system with an inert gas typically OFDN

• Gradually pressurise the system to 1.1 × allowable working pressure of the system, as prescribed on the 

system data plate

• Hold the pressure for several minutes and then gradually depressurise the system

• Check all parts of the system for deformation 

If no deformation of the system parts is found, then the test result is positive.

If the maximum working pressure is not displayed on the system, then it may be estimated based on the 

saturation pressure of the refrigerant at 55°C, although it does depend upon the local climate conditions; 

if the maximum ambient is expected to be higher, then the test pressure should also be increased. (Please 

also refer to Part 5.6.7.)

6.1.10 System evacuation

After the system has been sealed, leak checked and strength pressure tested, it is necessary to evacuate it 

in order to remove air, moisture and unwanted residual refrigerant. (Note that evacuation will not 

remove particulate matter.) If this directly follows refrigerant recovery or venting, it is necessary to flush 

the system with OFDN. If flushing it not possible because of the system configuration then some OFDN 

should be added to the system after recovery before evacuation takes place. This is necessary to prevent 

flammable mixtures occurring. 

When connecting the hoses between the system, gauge manifolds, and vacuum pump, ensure that the 

connections are secure and there are no potential sources of ignition nearby. Furthermore, ensure that 

the pump discharge is in an area free of potential sources of ignition. It is also necessary to ensure that a 

proper vacuum gauge is used since conventional manifold gauges will not provide a proper reading, and 

in fact often leads to the technician assuming that a good vacuum has been achieved when it may 

certainly not be the case.

The system should be evacuated to the desired pressure (typically 500 microns or less), and then left to 

stand for about 15 minutes to ensure that all of the refrigerant has been removed from the oil and any 

residual moisture has evaporated. If the pressure continues to rise, then this could be due to evaporating 

moisture or an (in-flowing) leak. If it continues after two or more evacuation procedures, then this suggests 

the presence of a leak, since there will be a finite quantity of moisture to remove. If the system is to be 

worked on (for example, breaking into it, brazing, etc), then the vacuum must be broken with OFDN. 

Ensure that the vacuum pump is of good quality and of appropriate capacity for the system, and that the 

oil level is correct. 

Along with other service machinery, the vacuum pump should be free of potential sources of ignition. 

This typically requires that the on/off switch be sealed or of a non-sparking type, alternatively it may be 

switched remotely at the plug socket provided this is located away from the refrigerant containing parts. 

6.1.11 Charging

Charging of refrigerant may be carried out in a number of possible ways, as with any other refrigerant, 

depending upon the location, type of system, available equipment and the desired accuracy:

• Electronic mass-flow controlled charging machines

• Volumetric charging by graduated cylinder

• Mass charging by (electronic) balance

• Charging to sight glass

• Charging according to system performance
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Typically, charging machines are limited to manufacturing facilities, so the remaining four options are 

possible for on-site charging. Out of these, mass charging using a balance is the preferred method, since 

it is the most precise, and the charge amount is normally included in terms of mass on the equipment 

dataplate. Nevertheless, virtually the same charging procedures are used with HC refrigerants as with 

any other types of refrigerant, except that certain considerations are particularly important:

• Prior to charging, ensure the system has been strength pressure tested with OFDN

• Prior to charging, ensure the system has been tightness tested (leak checked) 

• When connecting hoses between the refrigeration system, manifold gauges and refrigerant cylinder, 

ensure that the connections are secure and there are no potential sources of ignition nearby

• Ensure that contamination of different refrigerants does not occur when using charging equipment

• It is good practice to purge the hoses and manifold prior to charging to avoid contamination of the 

refrigerant; this should be done to minimise the emission of refrigerant but also whilst making sure 

that there is sufficient ventilation to dilute the release

• Hoses or lines should be as short as possible to minimise the amount of refrigerant contained in them

• Ensure that the refrigeration system is earthed prior to charging the system with refrigerant, to avoid 

the potential for static build-up

• Extreme care must be taken not to overfill the refrigeration system 

• Upon completion of charging, a further leak check must be carried out prior to leaving the site 

• After charging, carefully disconnect the hoses, attempting to minimise the quantity of refrigerant 

emitted

• Label the system when charging is complete (if not already)

• The mass of refrigerant charged into the system should be noted in a log-book and marked on a 

nameplate

With any type of mass charging, the method should be more accurate than with most other refrigerants 

because HCs have a lower density than CFCs, HCFCs and HFCs. Typically, a balance should have an 

accuracy of at least ±3% full-scale, especially when working on critically-charged systems. 

When charging the system the technician must be aware that HC refrigerant have a lower density than 

most other refrigerants, so typically 40 – 50% of the charge expected with, say R22, is used. This is an 

important consideration since over-charging a system is likely to result in extremely high pressures and 

subsequent catastrophic rupture of the system and massive discharge of the refrigerant. 

6.1.12 Repairs to electrical components

Before starting work on electrical components, the relevant power feed should be switched off before the 

sealed components are opened. If it is necessary not to switch off the relevant electrical components for 

repair work, the concentration in the atmosphere in the area concerned should be monitored continuously in order to warn people about a potentially dangerous situation should it arise. If a fault exists that 

could compromise safety, then no electrical supply can be connected to the circuit until it is satisfactorily 

dealt with. 

All electrical devices must not be potential sources of ignition, and this is normally achieved through a 

number of ways, typically:

• Using components that do not produce arcs, sparks, etc

• Using components that are sufficiently sealed such that they do not allow the ingress of flammable 

refrigerant

• Using components that are positioned in a locations where leaked refrigerant cannot and will not reach 

in the event of a leak

Full details are provided elsewhere (see Part 5.5).
202

Thus, when working on such electrical components, it is essential to ensure that:

• Faulty components that are intended not to spark, are not replaced by components that do spark

• Faulty components that are intended not to spark, are not modified in a way such that they do spark

• If replacing sealed components, it is done so using the same components or with components that have 

at least the same level of sealing

• After opening and/or working on sealed components, they are afterwards sealed as initially intended

• If working on or replacing specially positioned components, they are left fixed in their original positions

• Electrical cabling is and will not be subject to wear, corrosion, excessive pressure, vibration, sharp 

edges or any other adverse environmental effects

• All electrical apparatus is mounted securely

In many cases, a combination of special component positioning and component sealing is used to 

prevent a release of flammable refrigerant from reaching a potential source of ignition. Therefore it is 

essential that no alternations are made to the construction of the equipment as this could influence the 

desired level of protection, in a way that is not obvious to the technician. 

Furthermore, the technician should be aware that the construction of parts of an appliance, for example, 

positioning of barriers, walls, locations of pipe runs, etc, may indirectly affect the level of safety achieved 

with electrical components (or other potential sources of ignition). For example, if a pipe is repositioned 

next to an unprotected electrical component then a refrigerant leak may have a greater chance of entering 

it, or if a cable entry through an internal partition is not adequately sealed there may be a chance that 

refrigerant leaked on one side may migrate to an exposed electrical component on the other side.

When working on systems and equipment in general, it is important to check all electrical components 

to ensure that the intended level of protection (as intended during the protection of the equipment) has 

not been compromised through, for example, unauthorised modifications to the equipment, or from the 

effects of ageing, wear or mechanical stresses.

In addition to checking potential sources of ignition, other electrical parts should also be checked. For 

example:

• Terminal connections are tightly affixed and not loose, which could result in unintended arcing

• Protective conductor connections should be checked each time a repair is made

• Wiring and cabling should also be checked to make sure they are not damaged

If a defect is found, which puts the reliable operation of the refrigerating systems at risk, the installation 

should not be started up again.

Intrinsically safe components are the only type that can be worked on whilst live in the presence of a 

flammable atmosphere, although this is not normally used with RAC appliances or system. Test apparatus should also be of an appropriate rating. In all cases, in order to confirm that intrinsically safe components and test equipment are used, the “Ex-i” marking should be observed.

6.1.13 Routine system checks

When dealing with systems that use flammable refrigerants, there should be an emphasis on ensuring 

that the level of safety of the equipment and associated installation is maintained at a high level. This 

primarily involves checking, and if necessary making the required adjustments, so that the entire 

installation meets the requirements of the relevant safety codes, standards and regulations.

After completing any installation work, repair work or as a part of regular maintenance, such checks may 

include:
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• Ensuring the function of safety devices, including refrigerant detectors and mechanical ventilation 

systems

• That the minimum required airflow, if used, is being achieved

• Ventilation ducting and fans are free from debris and restrictions

• No piping has been installed in unacceptable positions

• Pipework and components are in good condition and not leaking or likely to leak

• Piping is fully protected from physical damage

• Mechanical connections are only located where permitted

• The system isn’t installed in a room that is smaller than the minimum size as permitted by the standards

• Ensure that any missing or illegible labels on components, devices or housing are replaced

• The appropriate manuals, handbooks, etc, are present where necessary

• Refrigerant cylinders are not being stored in the area

• Check that there is continuity of earth bonding for all equipment

• Ensure that the system and component mountings are secure

It is good practice to develop a check list to cover these items and for the technicians to note down that 

the relevant checks have been carried out.

6.1.14 Gas detection

Refrigerant detection is an essential requirement for technicians working on systems that use flammable 

refrigerants. Before, for the duration and after work has been completed, the area must be checked with 

an appropriate refrigerant detector to ensure the technician is aware of potentially flammable atmospheres.

Ensure that the gas detection equipment being used is suitable for use with flammable refrigerants, as 

determined by the detector manufacturer or supplier. Under no circumstances can potential sources of 

ignition be used in the searching for or detection of refrigerant. In particular, a halide torch (or any other 

detector using a naked flame) must not be used.

Electronic gas detectors can be used to detect flammable refrigerants. However, the documentation or 

manufacturer should be consulted in order to check that it is suitable for HC refrigerants. In some cases, 

the detector may require re-calibration (which should be done in a refrigerant-free area). Gas detection 

equipment is to be set at a percentage of the LFL of the refrigerant and must be calibrated to the refrigerant employed and the appropriate percentage of gas (maximum 25 % of LFL) is confirmed. 

If the presence of flammable refrigerant is suspected, all naked flames and other potential sources of 

ignition must be removed and/or extinguished.

6.1.15 Cylinder handling

HC refrigerants are available in a range of cylinder sizes, both refillable and non-refillable, depending 

upon the producer. Most refillable cylinders are equipped with pressure relief valves, and some cylinders 

employ special (unique) cylinder connections in order to differentiate them from other refrigerant 

cylinders, thereby reducing the possibility of muddling cylinder types. Some cylinders also employ an 

automatic excess flow valve within the liquid valve, which will close the valve if the refrigerant flow out 

of the cylinder is too fast (for example, if the refrigerant hose becomes disconnected).

Many of the requirements associated with handling flammable gas cylinders are dictated by national 

regulations, and these should be checked for individual national situations. Otherwise, the following 

include general refrigerant cylinder safe handling guidelines:

• Do not remove or obscure official labelling on a cylinder

• Always refit the valve cap when the cylinder is not in use

• Check the condition of the thread and ensure it is clean and not damaged
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• Do not expose cylinders to direct sources of heat such as steam or electric radiators

• Do not repair or modify cylinders or cylinder valves

• Always use a proper trolley for moving cylinders even for a short distance – never roll cylinders long 

the ground

• Take precautions to avoid oil, water and foreign matter entering the cylinder

• If it is necessary to warm the cylinder, use only warm water or air, not naked flames or radiant heaters, 

the temperature of the water or air must not exceed 40°C

• Always weigh the cylinder to check if it is empty – its pressure is not an accurate indication of the 

amount of refrigerant that remains in the cylinder

• Use only dedicated recovery cylinders for the recovery of HC refrigerant

• Always check that the cylinder is not beyond its mandatory safety check or pressure test date

• Ensure that the cylinder is not being used for a refrigerant that it is not intended to be used for

The storage of HC refrigerant cylinders is also normally controlled by national regulations; however, the 

following provides typical guidance:

• Cylinders should be stored in specific dedicated areas or cages, preferably outside, but in a dry, wellventilated area remote from fire risk 

• Access to storage areas restricted to ‘authorised persons only’, and such places must be marked with 

notices prohibiting smoking and the use of naked flames

• They should be stored at ground level, never in cellars or basements

• Access to cylinders should be readily accessible

• Never store cylinders in residential premises

• Use and store cylinders in an upright position

• The total quantity stored is usually be restricted to no more than a certain limit (for example, 70 kg in 

the UK)

• Static electricity build-up should be avoided

The transportation of cylinders is also normally controlled by countries’ specific national regulations. 

The requirements for HC refrigerant cylinders are typically the same as those for LPG, propane and 

butane used for fuel, etc. The following provides an indicative list of rules that may be broadly applicable 

in many countries:

• Carry written information giving the details of the substances carried (such as material safety data 

sheets or similar); this information must be available in an emergency so it should be located in a 

position where it is visible and accessible, and is often applicable to vehicles that are carrying a quantity 

of flammable gas above a certain quantity

• Know and understand the hazards and emergency procedures for handling these substances

• Carry a dry powder fire extinguisher of at least 2 kg capacity; it is recommended that the driver of the 

vehicle is trained in the practical use of fire extinguishers

• Cylinders must be located in an upright position with their valve uppermost and be properly secured

• Ensure adequate ventilation in the vehicle; this may require modifications to a closed van

• Display flammable gas hazard warning signs on the rear of the vehicle

• No naked flames or smoking allowed inside the vehicle

• Never leave cylinders in a closed vehicle unsupervised for longer than necessary

It is recommended that the refrigerant supplier is consulted in order to obtain the specific rules for a 

given country.
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6.2 INSTALLATION OF EQUIPMENT

6.2.1 Introduction

The installation covers a range of activities from a site survey to ensuring that the appropriate manuals 

are in place. The entire installation process is critical in ensuring the long-term safety of the equipment, 

for example, by ensuring that the safety features included within the design are correctly setup within 

the plant. The general procedure – with respect to safety matters – for the installation process is provided in Figure 68.

Figure 68: General procedure for installation of systems and equipment

Depending upon the type of equipment to be installed (for example, stand-alone appliance, appliance 

with pipework connection, remote system with pipework, or fully assembled system) the actual procedure may be abbreviated accordingly.

6.2.2 Preparation

Preparatory stages are important as they influence the safety of the actual installation activities, as well 

as helping to identify any fundamental incompatibilities between the equipment to be installed and the 

installation site. 

Initially, it is important for the responsible person, who is overseeing the entire project, to study the 

specification of plant design (or instructions in the case of an appliance installation), and to understand 

fully the purpose, operation and peripheral requirements of the equipment and associated components. 

Similarly, a site survey is required in order to be familiar with the installation location to identify any 

potential mismatch with the equipment to be installed. Always carry out a risk assessment to decide 

whether it is appropriate for the use of HC for the application under consideration.

6.2.3 Conformity to safety guidelines

Once the general requirements of the project are understood, it is necessary to carry out a check to 

ensure that the intended installation will meet with the requirements of the chosen technical guidelines, 

such as safety standards and regulations. A summary of the key aspects to consider are mentioned below. 

Further details may be found in Part 5.

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It is recommended that the refrigerant supplier is consulted in order to obtain the specific rules for a 

given country. 

6.2 INSTALLATION OF EQUIPMENT 

6.2.1 Introduction 

The installation covers a range of activities from a site survey to ensuring that the appropriate 

manuals are in place. The entire installation process is critical in ensuring the long-term safety of 

the equipment, for example, by ensuring that the safety features included within the design are 

correctly setup within the plant. The general procedure – with respect to safety matters – for the 

installation process is provided in Figure 68. 

Figure 68: General procedure for installation of systems and equipment 

Depending upon the type of equipment to be installed (for example, stand-alone appliance, 

appliance with pipework connection, remote system with pipework, or fully assembled system) the 

actual procedure may be abbreviated accordingly. 

6.2.2 Preparation 

Preparatory stages are important as they influence the safety of the actual installation activities, as 

well as helping to identify any fundamental incompatibilities between the equipment to be installed 

and the installation site. 
206

Charge sizes

In general, the mass of HC refrigerant within systems is limited, and this is normally done according to 

the type of system, the location and the size of the space, particularly in respect to occupied areas. In the 

case of systems within occupied spaces, a maximum charge size is specified for a given room size, or 

alternatively, a minimum room size for a given charge size. The approach requires consideration of two 

characteristics: 

• The first is an upper charge size limit, which is a function of the type of location and its occupancy

• The second is an allowable charge size, which is a function of size of the room that the refrigerant 

could leak into

Approximate values for public (A) and private (B) occupancies are summarised in Figure 69. Additional 

to this, other limits apply, such as:

• Entire systems located within a specially constructed ventilated enclosure for occupied spaces can have 

up to 5 kg of refrigerant

• For any system below ground level the upper limit is 1.0 kg regardless of occupancy type

• If all refrigerant containing parts are within a machinery room or in the open air then the charge size 

is not limited 

• If the charge size is less than 150 g there is no limit

Note that these limits apply to individual system circuits, thus is as system has two independent refrigerant circuits, the charge size limit is applied to each separately. Refer to Part 5.3 for detailed requirements.

Figure 69: Summary of HC charge size limits for single refrigerant circuit within an occupied space, 

dependent upon type of system

Minimising leakage

Systems must be designed to minimise the possibility of leakage. This includes avoiding mechanical 

joints, not using fusible plugs, applying proper protection against corrosion and mechanical damage, etc. 

General system design, piping and valves and component selection are discussed in Part 5.2.

Positioning of equipment and pipework

There are a variety of general rules that should be applied to the positioning of refrigerant containing 

parts. This includes restrictions for running pipework through other spaces (that are not being served by 

0,0 

0,5 

1,0 

1,5 

2,0 

2,5 

0 50 100 150 

maximum charge (kg) . 

minimum room floor area (m2) 

occupancy B; other systems 

occupancy A; other systems 

occupancy A or B; wall units for 

human comfort 

below ground level 

maximum charge (kg)

minimum room floor area (m2)

0 55 100 150

2,5

2,0

1,5

1,0

0,5

0.0

occupancy B; other systems

occupancy A; other systems

occupancy A or B; wall units for 

human comfort

below ground level
207

the RAC system) and ducting or service shafts, the location of pressure relief devices and outlets, the 

locating of condensers and other parts of the system outside, in case of a refrigerant release entering other 

parts of the building. Further details are provided in Part 5.6. 

Sources of ignition

All systems must have no sources of ignition (SOI) associated with it, such as sparking electrical components or hot surfaces. All parts of the equipment should be checked to ensure that the electrical and 

other components conform to the requirements, as laid out in Part 5.3. In summary, this means:

• Comply with the designated parts of IEC 60079, or an equivalent standard that makes electrical 

components suitable for use in an area in which an explosive atmosphere can occur, or 

• Not be located in an area where a potentially flammable gas mixture will accumulate, as proved by 

testing

Typically for larger systems where, in the event of a catastrophic leak where the concentration of refrigerant exceeds the LFL, the electrical equipment should be selected according to the requirements for explosive atmospheres. 

Electrical components should be selected and/or positioned carefully. Also, care should be taken to 

ensure that electrical terminals, including capacitor terminals are adequately tightened and secured 

against loosening and that adequate insulation is provided to avoid live parts shorting together. 

Depending upon the approach used for avoiding sources of ignition, its integrity over the lifetime of the 

equipment must be considered. Wearing of a component, such as through weathering or corrosion may 

also render it unsafe. Similarly, components that could be interfered with in the future should be installed such that it is not possible for it to be repositioned or affected in such a way that it becomes 

unsafe. 

Machinery rooms or enclosures

If in a machinery room a special enclosure is employed, it must meet with the rules, as detailed in Part 

5.6.4. In general, these address the following:

• Avoidance of potential SOIs

• Use of minimum flow rate for normal and emergency ventilation

• Suitable means of initiating ventilation such as air pressure switches or gas detectors

• Minimum open areas of walls to assist with natural ventilation

• Explosion protection

Safety controls

A number of components and associated control systems may be used to enhance the level of safety of 

the plant, such as:

• Pressure switches

• Pressure relief devices

• Flow switches

• Liquid level indicating devices

• Pressure indicators

• Gas detectors

It should be ensured that these are in place as and when necessary.
208

6.2.4 Site work

This involves the actual practical activities carried out by the installation technicians and engineers. 

Before starting work, the equipment and working areas must be checked to ensure they are safe. Examples include:

• Ensure that those who will be working on site are familiar with the implications of flammable refrigerants and all technicians handling HC refrigerants are competent to do so, and that there is adequate 

supervision

• Ensure all necessary equipment and facilities are available to carry out the work, such as calibrated 

handheld gas detectors, oxygen free dry nitrogen, proper charging equipment, and so on

• Components, pipes and fittings and materials conform to specifications and standards

• Ensure that all flammable substances (refrigerant and otherwise) are stored correctly

• All staff working in the area should be instructed about HC system being installed and to take extra 

precautions like “no smoking”

• Dry powder or CO2

 fire extinguisher should be kept adjacent to the installation area for any emergencies

In general, always carry out a risk assessment to decide whether it is appropriate to handle HC refrigerants on the site. Further details are provided in Part 6.1.2.

6.2.5 Testing

Following the completion of the construction of the equipment, the necessary tests must be carried out 

on the system. In particular, this includes:

• Tightness (“leak”) test (see Part 6.1.8)

• Strength (“pressure”) test (see Part 6.1.9)

• Functional test of safety devices, such as pressure switches, das detectors and emergency ventilation, etc

In addition, all electrical components must be checked to ensure they are not potential sources of ignition.

6.2.6 Marking and documentation

All the necessary marking and documentation must be in place, such that after the installation is 

complete, all the necessary instruction is available to ensure that anyone approaching the plant will be 

made fully aware of the risks and the appropriate conduct:

• Signs on equipment housing and components, including “flammable gas” warnings, “read the instructions”, “do not remove”, “no sources of ignition”, “authorised access only”, and so on

• Operating and handling instruction manuals, safety data sheets, maintenance sheets, safe working 

guidelines, and so on

Further details can be found in Part 5.7.
209

6.3 COMMISSIONING OF SYSTEMS AND INSTALLATIONS

6.3.1 Introduction

Commissioning is the advancement of an installation from the state of static completion to full working 

order, according to the specified requirements, which includes the setting-to-work of an installation and 

the regulation of the system. The general approach will be outlined here, but the focus will be paid only 

to the aspects that are implicated by the use of flammable refrigerants. 

Any complete installation including the complete refrigeration system should be commissioned, in terms 

of checking it against appropriate drawings and operational specifications, before the system is put into 

service. Particular attention must be paid to the safety features employed for the purposes of using 

flammable refrigerants.

The commissioning can only be carried out by a competent person and the results documented before 

the system can be put into operation. A single competent individual must have overall authority over the 

commissioning process. It should only be carried out according to a commissioning specification, which 

prescribes the detailed requirements with which the various commissioning services have to comply.

The proper commissioning of refrigeration equipment is crucial to ensure the correct operation of the 

safety features and to minimise the risk of the refrigeration system itself operating abnormally in a 

manner that could compromise safety. A poorly commissioned refrigeration system may have the 

potential to compromise the safety of building occupants and maintenance personnel. Often, the 

commissioning procedure is shortened due to pressure from the end user and/or other parties that want 

to have the plant operative, especially if there have been delays during the installation phase. Unfortunately, a restricted commissioning programme will nearly always result in the plant not working at its 

best and can greatly compromise the level of safety.

The responsibility for carrying out the commissioning is usually a contractual matter and that parties 

involved in any activities must comply with the relevant contract requirements. In any case, the operation of the system and safety features is often a matter for specialists and for this reason the design, 

installation and, particularly, the commissioning of a system will generally be required to be carried out 

by a competent person for the refrigeration equipment manufacturer and/or consultant and/or contractor. A number of different skills will be involved and strict attention to formal co-ordination between 

those involved is defined in the contract documentation. 

Normally the requirements for more comprehensive commissioning procedures increase with the size 

and complexity of the installation. For the larger projects, a commissioning management team should be 

formed to co-ordinate and oversee the commissioning process. Figure 70 provides an overview of the 

commissioning procedure for larger installations; smaller projects or appliances may omit certain stages.

6.3.2 Commissioning requirements

The following summarises the main requirements for a successful commissioning process:

• The equipment must be inherently commissionable, which must be specified at the outset of the design 

of the equipment

• All parties must allow sufficient time for the complete commissioning process and integrated into the 

overall programme

• Formation of a commissioning management team

• Ensure that all personnel involved need to be suitably competent

• Maximise off-site pre-commissioning activities, where applicable

• Implement post-occupancy checks to confirm the performance of controls and refrigerant leak 

checking. 
210

It is essential that the results of all checks and measurements are recorded in writing by the commissioning engineer together with any commentary, as appropriate. Breaks in the continuity of commissioning 

operations are likely and proper records will show the state of progress at any particular stage. Usually, 

the provision of commissioning records is an important part of the hand-over information for the 

building user. 

6.3.3 Preliminary design aspects

To ensure proper commissioning, information must be provided by the designer. It should be given 

either on drawings or in the design specification. The latter should always include a clear description of 

how it is intended the system should operate and the design parameters. The success and feasibility of 

the commissioning procedures will be influenced by the facilities provided in the design.

Figure 70: Overview and sequence of the key stages involved in commissioning
211

The refrigerating system and equipment should be designed and installed with all the necessary components and facilities and with adequate access to permit the required commissioning procedures to be 

properly carried out. It is essential to provide adequate safety controls and interlocks to protect the 

equipment during operation and throughout the commissioning process.

Details relating to the following should be included in the refrigeration specification:

• Description of the division of responsibility between the various parties

• Off-site and on-site pre-commissioning procedures

• On-site commissioning procedures

• Arrangements for management of delays

• Phased completion requirements

• Involvement in any complete system and sub-system performance testing

• System documentation

• Operator training requirements before and during the commissioning period (there may also be a 

requirement for post handover operator training)

• Post occupancy checks

6.3.4 Specification

In order to commission a refrigeration system the commissioning team must be provided with comprehensive details relating to the design/specification of the system. Details concerning the refrigeration 

plant and/or system to be commissioned must be supplied to the commissioning engineer. This specification information should include the following:

• Full details of the refrigerant, R-number, its safety classification, number of circuits, charge size of 

each, and whether the system is supplied fully charged, or with a holding charge

• A full description of the equipment and the operation of the refrigerating system, explaining the 

control system and logic

• Full details and comprehensive instructions regarding safety both for normal functioning of the 

refrigerating system and for occurrences which may arise as a result of a fault or accident

• Complete schematics of the refrigerating system prepared using industry recognised graphics and 

symbols, especially so that the location of refrigerant containing parts can be identified in relation to 

the different types of occupancies

• Reference to the safety codes, standards and other guidance to which the system was designed

Information must be provided in relation to refrigerant piping and accessories, identifying that which 

was made up during manufacturing and that which was installed on site. Where there is refrigerant pipe 

installed on site, the schematic drawing should include:

• Details of any refrigerant distribution pipework, the location of valves, mechanical joints, instrumentation, safety devices and fittings.

• Details of any refrigerant leakage detection system arrangements, together with numbers of sensors 

and alarm sounders or indicators, exhaust fans, ductwork and descriptions of their locations.

• Details of any systems or arrangements associated with the refrigerating system, such as pressure relief 

devices and associated pipework

• Manufacturer’s setting-to-work, operating and maintenance instructions for refrigerating equipment.

• The manufacturer’s specified settings for all safety devices

• Design temperatures, pressures and flow rates at stated operating conditions for all fluids at defined 

indication and measuring points

• Other environmental considerations that may be of relevance
212

Information relating to the electrical components (and other potential sources of ignition) must also be 

provided, such as:

• A list of all electrical components, identifying which are specially selected or positioned so as to not be 

a potential source of ignition

• The type of protection for each electrical component, where applicable

• Details of electrical protection devices for the compressor and other motors

• The design settings for starter overloads and any adjustable thermal cut-outs

6.3.5 Pre-commissioning

In order to minimise the on-site commissioning time and help negate the adverse effects of reduced 

commissioning timescales, as much pre-commissioning as possible should be performed off-site. The 

purpose of the pre-commissioning is to check that the equipment and system are in a satisfactory and 

safe condition for setting to work. It is desirable that the appointed commissioning specialist be a 

member of the team overseeing this work and that the work be part of the commissioning contract. 

These checks should be carried out shortly before the initial running of the plant:

• General site around installation to be cleared of rubbish and debris

• Ensure equipment, pipework, electric cabling is correctly labelled

• Packaged equipment delivered to site has any transportation points removed

A match between the actual installation and the requirements of safety rules must be established. Thus, 

it is important that the set of rules – whether a particular safety standard, interpretations of safety 

regulations, industry codes of practice or internally developed guidelines – are communicated to those 

carrying out the commissioning. In particular, the following aspects must be checked:

• Avoidance of flare or other mechanical connections where specified

• Pipework only passes through permitted areas, or if through ducts, conforms to the relevant rules

• Adequate protection against external damage, corrosion or tampering is ensured

• The charged mass of refrigerant is within the permitted refrigerant charge size limits, especially 

considering equipment positioned below ground level

• Refrigerant-containing parts are positioned only in locations that they are permitted

• The inclusion of all pressure safety devices, pressure indicators, level indicator, etc, are included as 

necessary

• The rules for potential sources of ignition are adhered to

• Special consideration is given to systems that are located outside and where leaked refrigerant could 

flow to, and similarly where emergency exhaust ventilation is directed

• Any machinery rooms or equipment enclosures are constructed as necessary

• All relevant markings and signage are applied as necessary, such as “flammable gas” and “authorised 

access only” warning stickers

• All relevant instructions and manuals are in place, and that they contain the necessary information 

and guidance

The following checks are to be carried out after the installation of the refrigeration plant:

• Pipework is complete and secured 

• Valves are provided as specified and fitted with sealed caps that are tight

• All flanged connections are correctly aligned, with the correct gaskets in place

• Capillary tubes must be free from damage and distortion

• Purging, charging and pump-down connections are provided
213

• Safety devices are fitted, e.g. a low pressure cut-out, high pressure cut-out, oil pressure differential 

switch (where fitted) and, chilled water low-temperature thermostat, low water flow rate switch and 

liquid line solenoid valves for start-up protection

• Automatic control arrangements are provided, solenoid valves fitted with coils in place 

• Sight glass and liquid level indicators 

• Suction, discharge and oil pressure gauges, or digital read out on solid state equipment, is fitted, or 

provision made for external connection of pressure reading

• Relief valves are correctly sized and vented to a safe location

• Flexible refrigerant connections are checked for tension and chaffing

The following checks to the electrical equipment must be carried out after the installation of the refrigeration plant. Note that for all equipment forming an integral part of the refrigeration plant these checks 

would initially be the responsibility of the manufacturer.

With all electrical supplies isolated, carry out the following:

• All electrical terminals are secure and tight

• The control panel to see that it is free from foreign materials (wire, metal chips etc) and clean if 

required

• Check that the main incoming power cables are properly connected

• Verify that all sources of electrical supply to the refrigeration plant are taken from a point of isolation

• Verify that the refrigeration plant earth terminal is properly connected to a suitable earthing point, 

and ensure that all internal earth connections are tight

• Check wiring from all hard wired safety devices, such as the high pressure cut out

• Ensure that remote overload trips are set correctly for compressor and oil pump motors 

• Set the current load limiting device (where provided) to allow operation at 100% load without tripping

• Check that mechanical interlocks have not been tampered with during the set up period

• All sealing to electrical components is in place un-damaged

With electrical supplies energised, carry out the following:

• Check that the declared voltage is available on all supply phases

• Where appropriate check that safety cut-outs de-energise the system

• Where motor power is substantial or reduced voltage starting or complex interlocks are involved, the 

control circuit logic and the starter operation should be tested before the motor is rotated (e.g. set any 

time delays associated with motor starter)

• In addition to the compressor starter operation, ensure satisfactory operation of any associated electrical controls, e.g. a liquid line solenoid valve, electrical heater on the oil failure control 

• Check for clean operation of all contactors, relays and interlocks

Certain operational checks must be carried out, as follows:

• For safety devices and automatic controls, check the settings and simulate the actuation of all safety 

devices and automatic controls for ancillary plant serving refrigeration systems to ensure correct 

functioning

• Operation of fans and that they are achieving minimum flow rate along ductwork

• Gas detection systems, automatic activation of alarms, shut-down procedures and initiation of exhaust 

ventilation, and so on
214

6.3.6 Refrigerant handling

Refrigerating plant may be of the factory assembled and packaged type or may be built up into a complete system on-site. In either case, certain checks will be required at some stage prior to operating the 

plant.

For factory-assembled systems:

• Observe pressure readings; where readings are lower than those specified by the manufacturer’s data 

and the ambient temperature, leak testing of the system will need to be repeated and where pressures in 

parts of the system are nominally atmospheric, evacuation and charging must also be carried out again

• Where pressures are consistent with the manufacturer’s data for the system and the ambient temperature, then further pressure testing and evacuation should not be necessary and where the system has a 

holding charge only, additional charging will be necessary

• In any case a leak test on all joints is recommended prior to applying a complete charge

Procedure for systems assembled on-site:

Before putting into service any refrigeration system, all the components or the whole system must 

undergo the following tests, where needed:

• Strength pressure test

• Leakage check (tightness test)

• Evacuation carried out (see Part 6.1.10)

• Refrigerant charging carried out (see Part 6.1.11)

• Functional test of safety devices

Finally, test of the complete installation must be complete before putting it into operation.

6.3.7 Setting to work and adjustments

Before operating the compressor for the first time (the compressor may have been operated briefly during 

the charging operation) a further visual check should be carried out on the complete system and, in 

particular, all refrigeration safety devices should be subjected to their complete cycle of operation.

Carry out the following:

• Set the refrigerant pressure controls in accordance with the manufacturer’s instructions or ensure that 

factory settings have not been disturbed

• Adjust the high pressure switch to the manufacturer’’ specified settings

• Ensure that if automatic reset is used, then short-cycling does not occur, or, if provided the time delay 

device is set correctly

• Check all pilot lights, the timer (to limit the number of starts per hour of the compressor) and the 

motor winding high temperature cut-out

Immediately prior to commencing a continuous test run on the refrigeration system check that:

• All refrigerant circuit shut-off valves are in the open position, except for the bypass valves, in particular 

ensure that the condenser liquid line valve is open

• Compressor suction and discharge valves are open

• Oil suction and discharge pressure gauge valves are open

• Solenoid stop valves of the evaporator are operational on the magnetic coil control

• Refrigerant pressure controls are reset, as well as the oil pressure control, the freeze protection thermostat and/or freeze protection pressure switch
215

6.3.8 Start-up, shut-down and running-in

Start the system as prescribed by the manufacturer or according to the plant designer. After running the 

machine for about 10 minutes, note the motor starting current and pressure gauge readings. Re-check 

the function of the pressure cut-outs and ensure that these de-energise the machine. Record the operative 

settings. The refrigerating system should now be in full operational order.

Carry out the full functional checks for any additional safety controls. Where applicable:

• Use calibrated gas mixture to apply to gas detectors, and follow the relevant sequence, such as pumpdown cycle, electrical shut-down, initiation of mechanical ventilation and audible and/or visual 

alarms, etc 

• Similar a less of refrigerant from the systems, and follow the relevant sequence

Follow through the manufacturer’s instructions, or the correct sequence as detailed in the design description to shut-down the complete plant, observing that any automatic or safety features operate satisfactorily. Throughout the above, note and record any irregularities in the shut-down cycle (e.g. noise, vibration, or unexpected pressure variation). Establish the cause, and where appropriate, rectify.

When all procedures above have been satisfactorily completed, the entire system should be set to operate 

and allowed to run for a continuous period of at least 72 hours under normal automatic control. It is 

recommended that the installation should be continuously supervised by a competent person for at least 

half of the run-in period.

After this period, carry out the following:

• Test the system for refrigerant leaks; this should be done at least twice during the running-in period

• Check the operation and calibration of automatic control and protection devices, including the 

satisfactory operation of the liquid line solenoid valve, automatic pump-down, low and high pressure 

cut-out, etc

• Check all mechanical equipment for excess heat, noise and vibration

6.3.9 Handover and documentation

On completion of commissioning, it is important that the end user or a representative be consulted to 

ensure that they are satisfied the system is working to the agreed design specification. The plant should 

not be handed over until both the end user and the installer are satisfied with its operation. A final 

submission should be made to the designed party (according to the contract). This should include:

• A full set of the details for the system design, drawings, equipment technical data, and safety mechanisms

• Full description of commissioning procedures

• Any problems identified, and what if any actions taken to resolve them

• Operating parameters including pressure, temperatures, flow rates, concentrations, etc, under which 

conditions 

• Operating, servicing and maintenance instructions and control settings for any major items of equipment included in the installation

• A list of recommended spare parts for critical equipment;

• Declaration of conformity relevant to the installed items of equipment as required by legislation

• Other information as required by the controlling authority to complete the health and safety file

• Other pertinent information (for example, the data-sheet in Appendix 9) 
216

6.4 ON-SITE AND WORKSHOP CONVERSIONS

6.4.1 Basic principles and warnings

Under certain circumstances, there may be a desire to convert a RAC system from a non-flammable 

refrigerant to use HCs. This approach may be considered for a number of reasons, such as: 

• A desire to improve the efficiency of a system

• To minimise the environmental impact

• Because it may be more cost-effective than using other refrigerant options

• If there are no other refrigerant replacements available

However, note that if existing refrigeration system is working correctly then there is normally no need to 

convert the system to use any alternative refrigerant.

Note that in this case, the term “conversion” is used. This is important as it distinguishes from other 

phrases such as “re-fill”, “drop-in” and “retrofit”. The reason for this is that when a non-flammable 

refrigerant (say R12) is replaced by another non-flammable refrigerant (say R134a), if any changes are 

required to the system, then they relate to performance (e.g., change of capillary tube length) or compatibility (e.g., change in oil type). However, when changing from a non-flammable refrigerant (say R22) to 

a HC refrigerant (say R290), additional considerations must be taken into account. These include 

identifying whether or not the HC can be applied given the particular circumstances, and if so, carrying 

out the required changes to the equipment that are related to mitigating the flammability risk. A switch 

from a non-flammable to a flammable refrigerant should be considered in terms of an entire conversion 

of the equipment, not just a change of refrigerant. 

For these reasons, it must be emphasised that carrying out a system conversion to use flammable refrigerant necessitates careful consideration of the implications and it is essential to weigh up the risks and 

benefits. If a conversion is to take place, then it should be done comprehensively, with care and with 

attention to detail. 

Given that a conversion to a flammable refrigerant represents a significant change in the purpose of the 

system, it must be understood that the conversion can only take place provided that the final product 

meets the requirements of the relevant safety standards and national regulations. 

In order to help explain the correct procedure more vividly, some examples of conversions are included in 

Appendix 2.
217

Figure 71: Decision chart for determining whether it is possible to convert a system to use HC 

refrigerant (in order to conform to the relevant standards)
218

6.4.2 Considerations affecting conversions

When approaching the choice of converting a particular system, it is important to follow a logical 

sequence of safety-related considerations to help make the correct decision. Such considerations include 

the following issues:

• The type and complexity of the equipment to be modified

• The environment and location within which the equipment is installed

• The quantities of refrigerant involved (in relation to the system location)

• The necessity to introduce additional emergency systems

• The ease or possibility of modifying parts of the system 

• The ease or possibility of handling the potential sources of ignition

A decision chart to assist with evaluating the suitability of the equipment (predominantly with respect to 

the requirements of the safety standards) is provided in Figure 71. This may be used to provide a good 

indication as to whether a system can be converted to use an HC refrigerant, although other specific 

aspects may need to be considered in addition; i.e., the requirements elsewhere within this handbook (for 

now systems) and the relevant safety standards.

Since the refrigerant charge and the location of the refrigerant-containing parts of the system have such a 

strong influence of whether or not a conversion is viable, the suitability can be approximated according 

to typical system types. Table 19 provides an indicative overview of the types of systems that have been 

found to be acceptable for conversion. The viability is indicated as follows:

• ✔ ✔ – often suitable

• ✔ – sometimes suitable

• ✖ – normally unsuitable

• ✖ ✖ – always unsuitable

As previously explained, each situation is unique in terms of the combination of system design and 

installation location and therefore each must therefore be evaluated independently. 

Two other issues should be considered with respect to the suitability of carrying out a conversion. 

Firstly, it is strongly recommended that companies set up special conversion workshops at their facilities 

(see Part 4.5). Thereby, systems can be removed form the site to the dedicated workshop in order to 

carry out conversions. There are significant advantages to this:

• Access to proper tooling and equipment is more likely

• The working area can be set up to handle the use of flammable refrigerants

• Expert technicians that specialise on HCs are more likely to be present

• There will be better and more immediate access to the required parts and components

Whilst it is understood that certain types of equipment may not be portable, this approach should be 

taken is possible. 

Secondly, companies involved in frequent conversions of a particular type of system should prepare 

dedicated “conversion kits” for their technicians, where each kit is dedicated to a particular type of RAC 

system. 
219

Sector Equipment type System type Viability

Domestic refrigeration Chiller cabinets

Freezer cabinets

Integral

Integral

✔ ✔

✔ ✔

Retail refrigeration Water coolers 

Chiller cabinets

Chiller cabinets

Chiller cabinets

Chiller cabinets

Freezer cabinets

Freezer cabinets

Freezer cabinets

Freezer cabinets

Integral

Integral

Remote

Distributed

Indirect

Integral

Remote

Distributed

Indirect

✔ ✔

✔ ✔

✖

✖ ✖

✔ ✔ 

✔ ✔

✖

✖ ✖

✔ ✔

Cold storage and food 

processing

Storage cabinets

Coldstores

Coldstores

Coldstores

Process cooling/freezing

Process cooling/freezing

Process cooling/freezing

Integral

Remote

Distributed

Indirect

Remote

Distributed

Indirect

✔ ✔

✖

✖ ✖

✔ ✔

✖

✖ ✖

✔ ✔

Transport refrigeration Road transport trucks

Refrigerated railcars

Reefer containers

Marine refrigeration

Integral

Integral

Integral

Integral

✔ ✔

✖

✖ 

✖

Domestic air conditioners, 

dehumidifiers and heat 

pumps

Portable units

Window units

Through-wall units

Split units

Hot water heating

Central heating

Integral

Integral

Integral

Remote

Integral

Integral/indirect

✔ ✔

✔ ✔

✔ 

✔ ✔

✔ 

✔

Commercial air conditioning 

and heat pumps

Split units

Multi-split/VRV

Packaged ducted

Central packaged

Positive displace chillers

Centrifugal chillers

Hot water heating

Central heating

Remote

Distributed

Remote

Remote

Integral/Indirect

Integral/Indirect

Integral

Integral/indirect

✔ ✔

✖ ✖

✖ 

✖ ✖

✔ ✔

✖ ✖

✔

✔

Transport air conditioning Cars

Buses

Trains

Aeroplanes

Remote

Remote

Remote

Remote

✔ ✔

✖

✖

✖ ✖

Table 19: Application areas for natural refrigerants – Refrigeration
220

6.4.3 Conducting conversions

If a conversion is to be carried out, the correct sequence of activities must be carried out in such a way 

that both the safety of the workplace is maintained as well as ensuring the inherent safety of the equipment. A suggested process is provided in Figure 72. In fact, most of the activities related to refrigerant 

handling during installation, maintenance, servicing and dismantling are also applicable here. 

The following steps describe the process in Figure 72. 

Estimate the HC refrigerant charge size

This can be done using the existing refrigerant charge. Therefore, obtain the current refrigerant charge 

size from the equipment data-plate (Mdp). Then, using the correction factors (Cf

1) in Table 20, estimate 

the equivalent mass for the chosen HC refrigerant (equation 22). 

MHC = Mdp × Cf (22)

The correction factor in Table 20 thus represents the percentage of mass of HC refrigerant required. For 

refrigerants not included in Table 20, the correction factor can be estimated as the ratio of HC liquid 

density to the existing refrigerant liquid density, at a temperature of around 50 – 55°C. 

Check all necessary tools present

Prior to carrying out any work, it is essential to ensure all the tools and equipment and also spare parts 

required for the work are to hand. (A check list for tools and equipment may be developed from Appendix 6.)

Fluorinated refrigerant

HC refrigerant

R600a R600a/R290 

(50%/50%)

R290 R290/R170

(94%/6%)

R1270

CFC-12 (0.43) † 0.40 n/a n/a n/a

HFC-134a (0.47) † 0.45 n/a n/a n/a

HFC-1234yf (0.53) † 0.50 n/a n/a n/a

HCFC-22 n/a n/a 0.42 0.41 0.42

HFC-407C n/a n/a 0.45 0.44 0.45

HFC-404A n/a n/a 0.51 0.50 0.52

HFC-507A n/a n/a 0.51 0.50 0.52

HFC-410A n/a n/a (0.51) † (0.50) † (0.52) †

† Would require change in compressor displacement

 n/a: HC refrigerant not applicable to system using existing fluorinated refrigerant

Table 20: Conversion factors ( ) to estimate equivalent HC charge size
221

Check the working area and system

Before handling HCs or any other refrigerant, it is necessary to ensure both the working area and the 

system are safe and that the technician gains familiarity with the system. The applicable guidelines are 

provided in Part 6.1.3.

Gain access to refrigerant circuit

Whether for HCs or any other refrigerant, the same rules apply for accessing the refrigerant system, as 

detailed in Part 6.1.4.

Recovery

Any remaining refrigerant within the system must be recovered, particularly since the refrigerant with be 

CFC, HCFC or HFC and therefore if released will be harmful to the environment. Furthermore, there 

are also safety implications associated with releasing non-flammable refrigerants as well. Therefore a 

recovery machine should be used to recover the existing refrigerant, and stored in a cylinder approved for 

that refrigerant. The guidance in this handbook (see Part 6.1.5) can also be used in this case, particularly with regards to prevention of refrigerant mixing, avoidance of overfilling, and marking the cylinder 

appropriately after use. (The guidance for handling cylinders in Part 6.1.15 should also be followed 

regardless of whether the refrigerant is flammable or not.)

Repairs

If it is necessary to carry out repairs to the system, then the system must usually be broken into. The 

approach detailed in this handbook (see Part 6.1.4) may also be used at this step. Subsequently the 

necessary repairs can be carried out (for which some of the guidance in Part 6.1.7 may be useful). At this 

point, it may also be beneficial to take the opportunity to conduct other, less critical repairs, such as oil 

changes, replacing filter driers, internal cleaning of the circuits, replacing damaged parts, and so on.

Design changes

The design changes that are made to the RAC system are critical to ensure that the safety requirements 

are met. It is essential that, based on the type of system, the location, occupancy and the HC refrigerant 

charge size, the appropriate safety features are integrated into the equipment. Failure to do this properly 

may result in a serious flammability hazard. (Part 5 of this handbook should be checked in this regards.) 

The major considerations are usually:

• Elimination of all mechanical joints from occupied space and minimisation of the possibility for 

leakage (see Part 5.2)

• Re-setting of pressure safety devices (see Part 5.6)

• Elimination of all potential sources of ignition (see Part 5.5)

• Setting up of emergency detection/ventilation/alarm system (see Part 5.6)

• Application of relevant markings and modifications to instructions (see Part 5.7)

It is re-emphasised that particular attention must be paid to addressing the potential sources of ignition. 

In all cases the following assessment must be carried out:

• Inspect the system and associated equipment, and note down all electrical components

• Determine which of the components could act as a potential source of ignition

• Decide how each of those potential sources of ignition will be handled, for example, by replacing with 

sealed components, using solid state devices or types, or placing within a fully sealed enclosure

• Consider also that electrical terminals must be adequately secured and sufficient insulation is provided 

to avoid shorting of parts

• Carry out the modifications accordingly
222

The marking of all equipment that contains HC refrigerant is also re-emphasised here. The appropriate 

“flammable gas” stickers must be placed on equipment housing entries and refrigerant access points, as 

well as on exposed piping.

Sealing the system

Upon completion of the work to the system, the circuit must be sealed according to the guidelines (see 

Part 6.1.7).

Testing the integrity of the system

Since the refrigerant circuit has been broken into, it is necessary to carry out leak tightness tests and 

strength pressure tests (see Parts 6.1.8 and 6.1.9, respectively). 

Evacuation

The system must be evacuated (see Part 6.1.10).

Refrigerant charging

Provided that the system is provided to be leak free, then it may be charged with the appropriate HC 

refrigerant, according to the quantity determined in above (based on Table 20). (General guidance for 

safe charging with HC refrigerants is in Part 6.1.11.) Ensure that the charged quantity is recorded on the 

equipment data-plate.

CONVERSION KITS

If enterprises are involved with carrying out conversions of existing systems, it is recommended that “conversion kits” are used. The reason for this is that it is too “convenient” for technicians – once at a site and already working on a system – to use short-cut methods for the 

conversion to HC refrigerant. Given the safety risk, this approach should be avoided. One way of 

helping to achieve this is to issue technicians with a comprehensive conversion kit that contains all the necessary bits and pieces. For example, such kits may contain data sheets (with 

conversion factors, room size/charge size estimations, etc), risk assessment forms, working 

instructions, sealed and solid-state electrical components, flammable gas stickers, valves, 

special fittings, and so on. If enterprises typically deal with a range of different systems, then 

it is sensible to have conversion kits that are better suited to each different type of system. 

271

Secondly, companies involved in frequent conversions of a particular type of system should 

prepare dedicated “conversion kits” for their technicians, where each kit is dedicated to a particular 

type of RAC system. 

CONVERSION KITS 

If enterprises are involved with carrying out conversions of existing systems, it is recommended that 

“conversion kits” are used. The reason for this is that it is too “convenient” for technicians – once at a site 

and already working on a system – to use short-cut methods for the conversion to HC refrigerant. Given the 

safety risk, this approach should be avoided. One way of helping to achieve this is to issue technicians with a 

comprehensive conversion kit that contains all the necessary bits and pieces. For example, such kits may 

contain data sheets (with conversion factors, room size/charge size estimations, etc), risk assessment forms, 

working instructions, sealed and solid-state electrical components, flammable gas stickers, valves, special 

fittings, and so on. If enterprises typically deal with a range of different systems, then it is sensible to have 

conversion kits that are better suited to each different type of system. 

6.4.3 Conducting conversions 

If a conversion is to be carried out, the correct sequence of activities must be carried out in such a 

way that both the safety of the workplace is maintained as well as ensuring the inherent safety of 

the equipment. A suggested process is provided in Figure 72. In fact, most of the activities related 

to refrigerant handling during installation, maintenance, servicing and dismantling are also 

applicable here. 

The following steps describe the process in Figure 72. 

Estimate the HC refrigerant charge size 

This can be done using the existing refrigerant charge. Therefore, obtain the current refrigerant 

charge size from the equipment data-plate ( Mdp ). Then, using the correction factors (Cf ) in Table 

20, estimate the equivalent mass for the chosen HC refrigerant (equation 22). 
223

Final checks

After charging is complete, it is important to carry out a series of final checks to ensure a safety and 

reliability of the system. These final checks include:

• Repeat leak checking (see Part 6.1.8)

• Repeat checks to electrical components (see Part 6.1.12)

• Carry out the routine checks (see Part 6.1.13) where relevant

If considerable modifications have been made to the system, a commissioning procedure based on the 

recommendations in Part 6.3 should be carried out.

Finally, initiate the operation of the refrigeration machine and run for a period of about 15 – 30 minutes 

to ensure it is working correctly.
224

Figure 72: Flow chart indicating the sequence of activities for converting a system to use HC refrigerant 
225

6.5 DISMANTLING

Decommissioning and disposal occurs at the end of a systems’ life, when it is to be taken out of service. 

The majority of the activities involved in this stage are broadly applicable regardless of the refrigerant 

used. In general, the following actions are necessary:

• Removal of refrigerant

• Removal of oil

• Dismantling of refrigeration system and associated equipment

• Delivery of refrigerant, oil and hardware to the appropriate collection stations

In particular, attention should be paid to the following aspects in relation to the handling of flammable 

refrigerant:

• Recovery of refrigerant

• Evacuating the system

• Flushing and leaving a holding charge of OFDN within the system

• Allowing ample time for the refrigerant to dissolve from the refrigeration oil

• Removing the refrigeration oil and storing in a container with a blanket of OFDN

• Marking of all the refrigerant cylinders, oil containers and system materials to show what they are and 

what the intended destination is

• Delivery of the recovered refrigerant to a refrigerant collection station for recycling and re-use if 

possible

• Delivery of the recovered oil to a collection station for recycling or destruction

• Delivery of the metals, plastics and other materials from the system construction to appropriate 

recycling centres

In the case of complete pieces of equipment, it must be labelled stating that it has been de-commissioned 

and emptied of refrigerant. The label is to be dated and signed. Ensure that there are labels on the 

equipment stating the equipment contains flammable refrigerant. 
226

7.1 Introduction

This part of the handbook is intended to help provide an illustration of how enterprises have integrated 

some of the concepts described within this handbook into the development of HC refrigeration and air 

conditioning systems. A number of case studies are presented here. It is hoped that other enterprises that 

will also begin to adopt the use of HC refrigerants within their products can learn from these examples.

These case studies provide a mix of different perspectives, including both manufacturers and end users, 

both small systems and large systems. 

• Benson Air Conditioning – a producer of split and larger air conditioning products; the examples here 

are split type systems

• Carter Retail Equipment (CRE) – a producer of retail refrigeration systems; the example here is 

integral water-cooled display cabinets

• De’Longhi – a producer of small room air conditioners as well as many other types of appliances; the 

example here is a portable room air conditioner

• Hindustan Unilever – a producer of a wide variety of food products; the example here is of HC 

ice-cream freezers of Hindustan Unilever within India

• Johnson Controls International (JCI) – a manufacturer of many type of RAC systems and components; and example here of a range of chillers 

• Lidl – a supermarket chain; the example here is the generic design of new supermarkets

• Palfridge – a producer of domestic and commercial refrigeration appliances; the example here is a 

range of commercial stand-alone commercial cabinets

• Victorian Transport Refrigeration – a producer of refrigerated transport and vehicle air conditioning systems

• Waitrose – a supermarket chain; the example here is the generic design of new supermarkets

In addition, there are many other companies within Europe, Australia and increasingly within Asia and 

South and Central America, which produce refrigeration and air conditioning systems using HC refrigerants. The interested parties are recommended to search the internet for such products.

7.2 Benson Air Conditioning (Australia)

Product information

Non-ducted and ducted split air conditioners, including cooling only, and reverse cycle and heat recovery 

products are produced. The capacity of the wall splits range from 2.4 kW to 12.5 kW, whilst the ducted split 

model range from 3.5 kW to 100 kW. All units use R290 and the charge sizes of the wall splits are from 

0.2 kg to around 1 kg. Products are made in Thailand and China. Over the past four years, many thousands of products have been sold primarily to the Austral-Asian markets, but also in certain other regions.

Development and design

All models are designed to the Australian safety standards AS1677-1 and AS1677-2 as a minimum, but 

various additional measures are introduced in order to exceed these requirements. Third-party approval 

PART 7: CASE STUDIES
227

of the design and construction of the units was obtained from the relevant authority within the Australian Government. Further, the air conditioners were optimised especially for the characteristics of R290, 

rather than being based on conventional HCFC or HFC design strategy.

Production and manufacturing 

The production line for the air conditioners was specially modified for the R290 products. This was 

partly to account for the different components needed for the construction of the units, but also to 

introduce more thorough and rigorous tightness (leak) testing regime. The products are not charged 

during production, so the layout of the production line did not need to be modified for hazardous areas. 

However, quality management systems were used to improve leak tightness, as well as re-training of 

workers in this respect. Charging is carried out on-site or at the distribution centre, depending upon the 

type of products. For this, strict procedures are put in place.

After sales 

All technicians that work on the systems in any way must have undergone the appropriate specialised 

training and be certified under the scheme operated by the Australian Government (TAFE) and the 

Benson internal training programme. Equipment owners and operators are requested to only accept 

service contracts with Benson, or with other companies whose technicians are suitably certified only. At 

end of life, a complete recovery and recycling service scheme is in place.

Barriers

The main barriers were associated with overcoming some state government legislation within Australia, 

as well as compliance to EU standards and achieving CE certification (particularly PED certification) for 

products for the European market.

Cooperation partners

There was no working with any cooperation partners.

Contacts

Steve Smith (bensonac@bigpond.net.au)

Benson split air conditioner
228

7.3 Carter Retail Equipment (UK)

Product information

Integral display cases utilising R1270 with a water-cooled condenser. The case design had to fulfil 

traditional retail specifications and be multiplexed in a conventional way.

Development and design

The standards employed were EN 378 Parts 1 – 4: 2008/9, IoR Code of Practice for A2/A3 refrigerants, 

EN 60335-2-24: 2003, and Dangerous Substances Explosive Atmospheres Regulations 2002 (DSEAR) 

and European ATEX Directive 95. The design was completed in line with the above standards and 

regulations to develop a water cooled (condenser) integral display case for use in a class A occupancy, 

with a charge not exceeding 1.5 kg, whilst maintaining a high level of safety, reliability, energy saving 

and client specific system integration. The design focused heavily on the above ensuring that components selected were already approved or tested for use with HC refrigerants. A large amount of simulation leak testing was carried out in house to ensure compliance with EN 378 standards and that sources 

of ignition were moved or components replaced where appropriate. The design and build were externally 

validated for compliance and further testing was carried out. All design and manufacture is in line with 

CRE ISO 9001 accreditation.

Production and manufacturing 

The business invested in an HC production line with a dedicated HC charging machine, comprising 

automatic evacuation, leak test and HC charging facilities. This line also has fixed leak detection and 

operational and emergency ventilation in line with DSEAR and ATEX regulations. Training on the safe 

handling of HCs was also provided for shop floor operatives.

After sales 

Product specific training (including safe handling of HCs) was provided at CRE for service providers 

responsible for maintaining the sites post installation. CRE has also provided any technical assistance 

required on site and developed safe systems of work (SSOW) for service technicians.

Barriers

The main issues with the development of the HC water cooled integrals were: -

• Little “official” data on HCs for the application. CRE worked with equipment OEMs on validating 

Hitachi scroll compressors to operate on R1270 with warranty

• A large financial commitment was made by the business

• Nervousness of other end users to adopt the concept mainly due to lack of understanding on HC refrigerants 

Cooperation partners

The main cooperation partner was Cool Concerns Ltd (UK) for external verification of design and 

applicable standards.

Contacts

Ian Garvey, Engineering Director (ian.garvey@cre-ltd.co.uk)
229

Diagram of Carter display case (left) with positioning and construction of condensing unit (right)

7.4 De’Longhi (Italy)

Product information

The products are portable air conditioners (single duct), using R290. They are currently manufactured 

in their factory in China and sold in Europe and Australia. De’Longhi started to manufacture them in 

1998, and since then several hundreds of thousand units are in use.

Development and design

The reference safety standard is EN/IEC 60335-2-40 with Amendment A1, and no additional design 

features above the standard requirement were applied. As for all De’Longhi products they got the 

certification of the product from third-party test house like IMQ or TÜV.

Production and manufacturing 

The production area was modified in the way that a leak detection system was added in the production 

line. The safety management systems follow ISO 9001 and are certified accordingly. The members of 

staff were trained by their Italian colleagues, which has long experience in the application of R290.

After sales 

Service and maintenance in the after-sales sector is carried out by their own technicians. The technicians 

attend regular training courses in the De’Longhi headquarters. To ensure that only competent people 

work on the equipment only their own technicians are allowed to repair the units. To handle end-of-life 

aspects they follow the European WEEE Directive and De’Longhi is member of a consortium for the 

treatment of electrical waste.

Barriers

Initially the safety standard did not consider the application of flammable refrigerants and this was the 

main problem. When the EN standard was not available we used a draft standard (IEC 61D/53/CD). 

As second problem was the lack of specific components (mainly compressors).

Cooperation partners

De’Longhi is not working with any cooperation partners

Contacts

Alberto Aloisi, Technical Manager (alberto.aloisi@delonghi.it)
230

Examples of De’Longhi room air conditioners

7.5 JCI (Denmark)

Product information

Two types of HC equipment are produced: air cooled and liquid cooled chillers – for many different 

applications – with a capacity range from 60 kW to 500 kW. The largest charge is about 25 kg per 

circuit with two circuits per chiller unit. The latest design of the larger chillers use screw compressors 

and are equipped with inverters and run from 30 Hz to 70Hz. To date, well over 1,000 units are currently in operation. The production began in 1996, and the main markets have been Denmark, Sweden, 

United Kingdom and Germany.

Development and design

The standard EN378 and the European Pressure Equipment Directive (PED) were applied, where PED 

is the most challenging part. The European ATEX Directive is not relevant, so therefore additional 

design features were necessary to be applied. (This was evaluated by TÜV who concluded that ATEX 

was not relevant for the chillers). The approval and certification of the design and its serial production of 

the product as required by the PED were achieved. 

Production and manufacturing 

There was no need to modify the production area. However it was important to regularly consider the 

safety of the control panels and components, particularly with regards to their positioning. The compressors and the main parts are monitored by pressure in order to detect leakage. Staff training was carried 

out both within the workshop and in the field on an individual basis.

After sales 

All persons that work on the systems must be trained in safe refrigerant handling, so it is ensured only 

competent persons work on the equipment. In some cases servicing and maintenance is carried out by 

external contractors in which case the training would then have also be done externally. In either case 

the duration is two days of training. End-of life aspects are handled as any other refrigeration system.

Barriers

The main barriers are in the mindsets of any parties involved.

Cooperation partners

They worked with notified body to achieve the PED approvals through and they have communicated a 

bit with TÜV, and also worked with a training provider.

Contacts

Alex Cohr Pachai, Technical Manager (Alexander.C.Pachai@jci.com)
231

A new JCI air cooled R290 chiller

7.6 Hindustan Unilever / Kwality Walls Ice Cream (India)

Company information

Hindustan Unilever Limited (HUL), a subsidiary of Unilever, is India’s largest FMCG company. When 

reaching the point-of-sale (e.g., retail shop) the ice cream products are stored in freezer cabinets. For the 

sales of ice cream to the consumer, the business relies on over 2 million ice cream cabinets placed 

worldwide at the points of sale. 

Product information

In 2000, Unilever committed to stop buying HFC cabinets by 2005, replacing new cabinets using R290. 

By early 2010 Unilever had around 500,000 HC cabinets in use around the world. The size of the 

equipment varies between 150 and 400 litres storage volume and the refrigeration capacity varies from 

100 and 300 W. The rollout in India started in 2007 for HUL and by early 2010, there were 7,000 

cabinets using R290; the plan is to double this figure by 2015.

Development and design

The standard IEC 60335-2-89 is followed, but also taking into consideration national regulations apply, 

they take precedence. In addition, Unilever has commissioned quantitative risk assessments (QRA) by 

independent establishments and recommendations from these have been included in functional specifications prepared for the cabinet suppliers. Although the manufacturers have responsibility for the correct 

design of their equipment, Unilever cannot ignore the importance of design on the safe operation of the 

cabinets and therefore to ensure that cabinet manufacturers pay attention to important design aspects, 

Unilever issues them with functional specifications. It is then up to the manufacturer to demonstrate to 

Unilever that they have considered each point in the specifications. Unilever has undertaken initial field 

trials of HC cabinets in various countries during 2000 to 2004, with no reported problems in performance or safety. For the Indian market, additional trials in special climate simulation tests ascertained that 

the cabinets performed reliably under extreme tropical conditions, and withstood tough handling during 

transportation. Also field trials in India have been undertaken successfully. All trials confirmed that HC 

cabinets are at least as safe and reliable as their HFC containing equivalents, and also have on average a 

10 % less electricity consumption. Unilever developed a detailed Rollout Summary Document, and a 

Safe Servicing Training Package. This package acts as the basis for a local rollout implementation 

strategy in a specific country or region.

Production and manufacturing 

India does not have a commercial refrigeration equipment manufacturer with capabilities to manufacture 

ice cream cabinets with HC refrigerants. Cabinets have been imported from other Asian countries, where 

several Asian suppliers collaborate with European manufacturers. The cabinet manufacturers are responsible for necessary production area modifications, safety management systems and manufacturing staff 

training.
232

After sales 

Transporters are trained to handle the cabinets carefully. Each outlet is inspected before the cabinets are 

being installed and post-installation checks are carried out to ensure that the placement of the asset is 

according to requirements. 

Every cabinet has to go through a pre-dispatch inspection before being deployed in the market. Hindustan Unilever use own service stations with 3rd party service providers- Service stations have been made 

HC safety-compliant. Safety measures such as fire extinguishers, improved electrical infrastructure, 

signboards, first aid kits, personal protective equipment, were installed. Exhaust fans were installed to 

ensure rapid dispersion of refrigerant in case of leakage.

Training is done in-house and covers technical and safety aspects. The training sessions include classroom as well as practical training. To ensure that only competent personnel work on the equipment, 

written evaluation tests are undertaken, and it is mandatory to pass the tests to get the formal license 

to service HC cabinets.

Regarding end-of-life, the mother company Unilever has a global “cabinet disposal policy” which ensures 

that an environmentally benign way of disposal is applied locally. 

Barriers

The main barriers were found to be:

• A lack of Indian manufacturers of HC cabinets and HC components (i.e. compressors); the short term 

option is to import from other countries

• A lack of skilled technical manpower, and this has been overcome by developing and applying in-house 

training concepts

• Since there were no suppliers for dedicated HC spare parts in India, these have to be imported from 

other countries in the region

• Availability of HC refrigerant in India; even importing is very complicated, as all imported cylinders 

do not have the approval of the Indian Commissioner of Explosives – it took ten months to find a 

supplier who had the required licenses and permissions to import cylinders and refrigerant (from Italy)

• There is a lack of clarity, particularly but not exclusively in India, with regards to the legislative 

framework for use of HC as refrigerant in commercial appliances, on safe storage of HC cabinets and 

HC refrigerant, on service technician skills requirements, and on service station safety compliance – 

joining forces with all stakeholders would be the way forward to overcome this

Cooperation partners

In the initial phase of HC cabinet development, Unilever cooperated with several partners on the 

assessment of potential risks of this technology. In particular:

• Development and design of HC cabinet technology has been done in close cooperation with some key 

cabinet manufacturers

• Together with specialist consultants, Unilever developed standard training material for service technicians, used as the basis for dedicated local training concepts, as described here in the Indian rollout case

Contacts

Baasit Shukri, National Cold Chain Manager, Hindustan Unilever (Baasit.Shukri@Unilever.com)

Berty Jacob, Group Leader Business Systems Technology (Berty.Jacob@Unilever.com)

Rene van Gerwen, Global Lead Engineer Refrigeration & HVAC (Rene-van.Gerwen@Unilever.com)
233

Kwality Wall’s ice cream cabinets with HC refrigerant located at point-of-sales in India

7.7 Lidl (Germany)

Product information

Supermarket systems consisting of a compact plant for outdoor installation with indirect cooling 

(medium temperature and air conditioning) and a heating system, using R290 in the primary circuit 

and potassium formate brine in the secondary circuit. An additional low temperature stage is uses R744 

direct expansion or also with a secondary circuit with brine. The low temperature stage is built in as 

cascade in the medium temperature stage. The system designed for Lidl supermarkets has the following 

capacity data:

• Medium temp.: 55 kW cooling capacity

• Air conditioning: 40 kW cooling capacity

• Heat pump: 60 kW heating capacity (without waste heat)

Using the standard housing a cooling capacity up to 200 kW is possible. The charge size depends on the 

overall refrigerant quantity of the plant lies between 40 and 80 kg of R290. Currently there are four 

plants in operation in Germany. In May 2010, the roll-out for all newly built Lidl stores in Germany will 

start. In total there will be approximately 200 plants in operation by mid-2012. At the same time, the 

first plants in Denmark and in Switzerland will also come into operation. The first integral plant has 

been produced in 2008. 

Development and design

The following standards and regulations were applied: GPSG, 11. GPSGV, RL 94/9/EG (ATEX 95), 

TRBS 2152, BGR 104, BGR 500, RL 2006/42/EG (MRL), RL 97/23/EG (DGRL), EN 378 1-4. TÜV 

SÜD; Drees & Sommer Advanced Building Technologies; Fa. Effektivplan; DGNB (German Sustainable Building Council); DENA (German Energy Agency) were involved in approving design and 

certifying the products. 

Production and manufacturing 

The production area was modified in a way that the final assembly hall of Futron (the machinery 

supplier) was completely reconstructed to better comply with the requirements of serial production. As a 

final control, a test plant for the simultaneous testing of up to three plants was built. The whole production area is equipped with gas sensors and a ventilation system according to EU ATEX Directive, 

corresponding to the integral plant concept itself. In the case of an accident, the whole building area will 

be switched off from energy supply. Safety management systems put in place included the whole production area being furnished with instructions and procedures for the safe use of flammable refrigerants exist.

After sales 

There was no need for training, because Futron GmbH is specialised on the use of natural and flammable refrigerants since many years. Futron has only trained expert staff. Operation and maintenance can 
234

also be conducted by external expert staff. A precondition for this is a certificate of specialist knowledge 

and extensive training from Futron. In addition the Plant is 100% recyclable. 

Barriers

The main barriers were the outdated and untenable prejudices against flammable refrigerants and some 

difficulty in the availability of components (due to low market demand) delayed the immediate implementation. An economically reasonable realisation of the concept was possible by adhering to the 

following design features:

• Creating a compact device for outdoor installation

• Avoiding the application of ATEX Directive

• Using a secondary circulation for cold transmission

After intensive talks with several component manufacturers and by highlighting the commitment of the 

project from Lidl as a large end-user, the necessary accreditation and approval was given. In the meantime, there exists a good availability and a normal competition situation for the necessary components.

Cooperation partners

The first integral-plant is a cooperation project between Lidl and Futron. Lidl (as an important end-user) 

took part in all phases of the project. Therefore it was possible to design the plant optimised for this kind 

of application. All integral-plant-series designed by Futron will be customized in accordance with the 

requirements of the End customer.

Contacts:

Andreas Schwarz, Area manager (Andreas.schwarz@lidl.de)

A Futron integral plant at Lidl supermarket

7.8 Palfridge (Swaziland)

Product information

The Palfridge factory is in Swaziland, southern Africa. The products are sold throughout the region of 

southern and Central Africa, but also into the Middle East and in the future to Europe. They manufacture a range of stand-alone commercial refrigeration units, such as bottle coolers, freezers, storage 

cabinets and display cases. The capacity of the cabinets range from small (around 50 litres) to larger 

models (over 2,000 litres). Most of the models have a HC charge size of less than 150 g although some 

exceed 300 g. Both R290 and R600a are used, depending upon the type and size of cabinet and the 

operating temperature. Over 100,000 units are produced annually, and the entire production is being 

shifted from HFCs to HCs over a 12 month transition period. The transition began in 2009 is expected 

to be completed in 2010.
235

Development and design

The main standard that was employed for the appliances is IEC 60335-2-89, however, where charge sizes 

exceed 150 g, the European standard EN 378 was used. The local testing laboratories do not have the 

appropriate testing equipment for the tests specified in IEC 60335-2-89 (such as the leak simulation 

tests). Therefore equipment was bought in specially (supplied by GTZ) and modified accordingly to 

tested the refrigerators at the Palfridge facilities under the supervision of an external laboratory. Conformity to the standards will be through self-declaration and CE marking. (The local test houses are 

using Palfridge staff to train them!) We have made various other pieces of test equipment in house.

Production and manufacturing 

Nearly the entire production line was changed, including new tightness testing equipment, evacuation 

lines, charging equipment and performance testing areas. 

The bulk storage or tank storage area required complete re-construction. The entire installation was 

approved by VDE. Although much of the above was not entirely necessary to implement HCs, it provided the opportunity to radically redesign the factory layout, the production line routes and product 

testing. This has resulted in a much faster manufacturing process leading to large energy and resource 

savings, improved quality product and a significant cost reduction.

Palfridge is currently working towards implementing ISO 9001, which will be in place by July 2010. 

ISO 14000 is scheduled to follow. The laboratory standard ISO 17025 is also being implemented and 

expected to be completed by end 2010. In addition there is a new in-house computer aided Safety and 

Maintenance System that documents the total servicing , inspection and repair of the installation.

It is important to highlight that in changing the models to use HCs, various structural changes were 

made in fact it afforded an opportunity to re-design the entire cabinet to better suit the new production 

process, improve performance improvement and quality. As an example, for two of the models the reduction in energy consumption is between 30 to 40% compared to the conventional model, partly due to 

the HC and partly the re-design.

Training to production line staff was carried out by the suppliers of the production line equipment. 

Design engineers and technicians were provided with general HC safety training, including training of a 

specific trainer to proliferate the HC safety training to field technicians.

Another notable benefit of the conversion is the change in the culture of the factory. Previously the 

factory was a typical “third-world” plant with dilapidated structures and machinery and untidy workplaces; the operators were scruffy and quality was comparable to the working conditions with very little 

pride and self esteem. After the installation of the new plant, the cleanliness and tidiness of the facility 

and the workers has dramatically improved, but in addition, the production process now operates in a 

much more synchronised manner, whilst the greatest change is that the workers themselves seem to be 

proud and dignified, helping to contribute to much higher quality products and working environment.

After sales 

Service and maintenance is and will continue to be carried out using internal and external technicians. 

However, all technicians related to the enterprise will receive thorough HC safety training and certification and a similar training and certification scheme is being carried out across the region, particularly 

targeted at distributors, to ensure that any servicing is conducted by a competent technician. Palfridge 

has already identified all the field technicians, created a database and already begun preliminary training 

in the major centres. Palfridge staff has set up proper HC workshops in these centres which include 

service equipment and ventilation systems. Technicians are trained by the factory engineers at these 

centres on both theoretical and practical aspects. The trainees themselves retrofit or change compressors 

and re-charge using HC. It is envisaged to supply the technicians with evacuating, charging and servicing equipment. A second part of the workshop will contain a written exam and a practical testing, both 

designed by Palfridge. Successful candidates will be issued with a certificate of competence. This training will be held yearly and will also serve as an opportunity to pass down product information to the 
236

technicians. Palfridge has also begun training with a commercial training centre who would continue 

training other existing and aspiring technicians. Locally Palfridge also held multiple day workshops with 

students from the local Universities and technical colleges. 

Barriers

There were a few barriers. One was the time taken to analyze and redesign each cabinet model. Also, 

HC were not available locally and very few people have even heard of it. Palfridge first had to find a 

supplier to invest in importing HCs, which included them acquiring additional tanks with DOT rating. 

With regards to the construction of the production facilities, there were very few local contractors that 

could execute work to the high level of safety requirements from TÜV. The other main barrier was 

changing the culture of the workforce to understand the safety issues and obeying the documented 

standards especially the maintenance team.

Cooperation partners

GTZ Proklima

Contacts

Roy Singh, Technical Director (roys@palfridge.com)

Charging area of production line (left) and example of some HC cabinets (right)

7.9 Victorian Transport Refrigeration – Refrigerated transport 

and vehicle AC (Australia)

Product information

Victorian Transport Refrigeration (VTR) developed a range of refrigerated transport systems from small 

1 tonne capacity vans through to 5 tonne truck systems. Depending on the capacity and temperature 

level, these systems use a R290/R170 blend, R290 and also a blend of R290/R600a. These transport 

system are purpose built, but are also tailored to the particular needs of the customer. Although the 

units have originated from the HCFC product range, the systems have been carefully optimised specifically for the HCs and also to minimise the refrigerant charge quantity such that all HC models contain 

significantly less charge than conventional systems. Several hundred systems have been supplied since 

production began a couple of years ago.
237

Development and design

No international or national (Australian) safety standards or guidelines exist specifically for transport 

refrigeration systems although a draft safety standard AS 1677 Part 3 (unpublished) applies to the use of 

HC for motor vehicle air conditioning systems. Therefore in absence of a formal standard, VTR designs 

and constructs the systems according to the requirements of AS 1677 Part 2 (for static systems), and also 

observes the provisions of the Australian and New Zealand “Refrigerant handling code of practice 2007” 

Parts 1 and 2 and the “The Australian automotive code of practice for the control of refrigerant gases 

during manufacture, installation, servicing or de-commissioning of motor vehicle air conditioners 2008” 

(which apply to the handling of fluorinated refrigerants). Although these documents do not explicitly 

cover the use of HC refrigerants, they nevertheless serve as a point of reference to inform the design and 

maintenance of the systems.

Production and manufacturing 

Systems are assembled from commercially available components within the production facilities, where 

they are also fitted to the vehicles. Apart from a slightly different production route to ensure the correct 

components are used and that potential sources of ignition are avoided there are no significant differences. However, a checking process is necessary to ensure that the vehicle or trailer within which the 

refrigerating parts are to be installed does not include any potential sources of ignition. Since the systems 

are charged after installation, the production area does not need to address the requirements for hazardous areas. However, for charging and servicing of systems, a dedicate area is used. The facilities employ 

internal quality procedures to ensure that the necessary precautions have been put in place at each stage 

in the process. 

After sales 

After-sales service and maintenance is carried out by VTR technicians who provide on-site service and 

regular maintenance programmes. Careful records of systems in the field are kept, and preventative 

maintenance schedules are applied to ensure reliability, and to avoid the risk of client exposure to 

expensive system failures. All staff are qualified refrigeration mechanics through the technical “TAFE” 

colleges and hold Certificate 3 qualifications combined with the standard four year apprenticeships. 

Specialised training is not provided for transport refrigeration by the TAFE system, so this is provided in 

house, with technical support and advice from the refrigerant suppliers.

Barriers

One major barrier is, as identified above, the lack of appropriate safety standards. Whilst it has been 

possible to develop internal guidelines to enable the development of HC products, the availability of an 

industry code of practice or national or other standard would of course help to resolve acceptance issues. 

However, the main barrier that was faced have not been technical or commercial, but were instead due 

to peer pressure from industry peers and competitors who alleged it was not feasible to use HCs, and 

that the refrigerant wouldn’t work or would damage equipment. Despite such significant resistance, 

VTR persevered with the product development and commercialisation. As a result there is growing 

positive feedback from customers and users based on the evidence and practical experience.

Cooperation partners

The main cooperation partner was their refrigerant supplier (Hychill Australia) who worked closely with 

VTR to provide technical advice and to offer guidance on system design and maintenance issues.

Contacts 

Rohan Cox (scms01@bigpond.com)

Ross Bradshaw (ross@hychill.com.au)
238

Installed refrigeration system inside a truck/mobile cold rooms

Product information

Supermarkets using R290 and R1270; up to 70 integral items including cabinets and cold stores, all of 

which are interconnected by water piping. The average charge of a single system is around 700 g, and 

with the total quantity of refrigerant approximately 75 kg.

Development and design

The reference safety standards used were: EN 378 Parts 1 – 4: 2008/9, IoR Code of Practice (A2 A3 

Refrigerants), EN 60335-2-40: 2003, EN 60079-0: 2009, EN 60079-10-1: 2009, EN 60079-14: 2008, 

EN 60079-15: 2005. The design was completed by several OEM’s providing individual pieces of equipment including cabinet manufacturers and chiller manufacturers. The overall design consisted in simple 

terms of water cooled integral direct expansion HC cabinets, a chilled water circuit (between shop floor 

and chillers) and roof mounted HC water chillers. Cold air retrieval from the shop floor is used to 

comfort cool the shop floor and back of house areas of the supermarket, a small amount of the heat is 

rejected from the cabinets directly to the shop floor by way of a de super heater coil in the compressor 

discharge prior to the water cooled plate condenser. The site also incorporates other integral cabinets and 

appliances that are air cooled HC systems i.e. icemakers and service cabinets. Small HC split AC systems 

are used to cool small offices and staff dinning room during times of warm ambient conditions.

Production and manufacturing 

The production of the HC equipment was carried out by approximately 10 OEM’s and the equipment 

shipped to site pre-commissioned and ready to run. Several of the OEM’s were already producing HC 

variants of their standard HFC product range, others began from scratch. Generically OEM’s have 

modified their manufacturing facilities to comply with relevant standards including DSEAR / ATEX 

and have purchased automatic HC charging equipment, especially for smaller cabinet charge sizes <800 g. 

After sales 

The sites are maintained by contractors who have all undergone HC refrigerant handling training as 

specified by Waitrose. There are currently (May 2010) over 5,000 HC trained service personnel operating across the UK and this number is increasing weekly.

7.10 Waitrose / John Lewis Partnership (UK)
239

Barriers

There are still several ambiguities and contradictions in standards that where primarily written to 

include HC systems with very small charge sizes. Many of the refrigeration specific standards can in 

places contradict/ overlap with DSEAR / ATEX and this continues to be debated. 

Cooperation partners

Waitrose worked with over 10 suppliers to develop and deliver the HFC free supermarket this included a 

consultant specialising in HC refrigerants and involved verification of all the OEM’s equipment design 

and manufacture to ensure compliance with the relevant standards.

Contacts

Les King, Refrigeration Manager (les_King@waitrose.co.uk)

HC chiller (left), system layout (centre) and example of display case (right) in Waitrose store
240

BIBLIOGRAPHY, STANDARDS, FURTHER READING

National standards

• BS 4434: 1995 (withdrawn) – Specification for safety and environmental aspects in the design, 

construction and installation of refrigerating appliances and systems (UK)

• ASHRAE 15-2007 – Safety Standard for Refrigeration Systems (USA)

• ASHRAE 34-2007 – Designation and Safety Classification of Refrigerants (USA)

• UL 250: 1993 – Standard for Safety of Household refrigerators and freezers (USA)

• UL 471: 2006 – Standard for Safety of Commercial Refrigerators and Freezers (USA)

• AS/NZS 1677:1998/Amdt 2: 2000 – Refrigerating systems - Safety requirements for fixed applications 

(Australia/New Zealand)

• SNI-06-6500-2000 – Refrigerant application for fixed Installation (Indonesia)

• NPR 7600: 2001 (withdrawn) – Application of natural refrigerants in refrigeration and heat pumps 

(Netherlands) 

• DIN 7003: 1995 (withdrawn) – Refrigeration plants and heat pumps with flammable refrigerants 

group L3 – Safety requirements (Germany)

• SN 253130: 2000 – Refrigeration plants – Requirements in relation to the site (Switzerland)

European standards

• EN 378: 2008 – Refrigeration Systems and Heat Pumps –Environmental Requirements

• EN 15834: 2009 – Refrigerating systems and heat pumps — Qualification of tightness of components 

and joints

• EN 1127-1: 2007 – Explosive atmospheres – explosion prevention and protection. Basic concepts and 

methodology

• EN 1012-1: 1997 – Compressors and vacuum pumps. Safety requirements. Compressors

• EN 1012-2: 1997 – Compressors and vacuum pumps. Safety requirements. Vacuum pumps

• EN 12178: 2003 – Refrigerating Systems and heat pumps. Liquid level Indicating Devices. Requirements, testing & marking

• EN 12263: 1999 – Refrigerating systems and heat pumps. Safety switching devices for limiting the 

pressure. Requirements and tests

• EN 12284: 2003 – Refrigerating Systems and Heat pumps. Valves. Requirements, Testing and Marking

• EN 12693: 2008 – Refrigerating systems and heat pumps. Safety and environmental requirements. 

Positive displacement refrigerant compressors.

• EN 13136: 2001 – Refrigerating systems and heat pumps. Pressure Relief Valves and their associated 

piping. Methods for calculation.

• EN 13313: 2008 – Refrigeration Systems and Heat Pumps. Competence of Personnel

• EN 13463-1: 2001 – Non-electrical equipment for potentially explosive atmospheres. Basic method 

and requirements

• EN 13463-5: 2003 – Non-electrical equipment for potentially explosive atmospheres. Part 5. Protection by constructional safety

• EN 13463-6: 2005 – Non-electrical equipment for potentially explosive atmospheres. Protection by 

control of ignition source

• EN 14276-1: 2006 – Pressure Equipment for refrigerating systems and heat pumps. Vessels. General 

requirements.

• EN 14276-2: 2007 – Pressure Equipment for refrigerating systems and heat pumps. Piping. General 

requirements.

• EN 14797: 2006 – Explosion venting devices

• EN 14986: 2007 – Design of fans working in potentially explosive atmospheres

• EN 15198: 2007 – Methodology for the risk assessment of non-electrical equipment and components 

for intended use in potentially explosive atmospheres
241

• EN 1736: 2000 – Refrigerating Systems and Heat Pumps, Flexible Pipe Elements, Vibration Isolators 

and Expansion joints.

• EN 60079-0: 2006 – Electrical apparatus for explosive gas atmospheres. General requirements

• EN 60079-10-1: 2009 – Electrical apparatus for explosive gas atmospheres. Classification of hazardous 

areas 

• EN 60079-14: 2003 – Electrical apparatus for explosive gas atmospheres. Electrical installations in 

hazardous areas (other than mines)

• EN 60079-15: 2003 – Electrical apparatus for explosive gas atmospheres. Type of protection “n”

• EN 60079-17: 2003 – Electrical apparatus for explosive gas atmospheres. Inspection and maintenance 

of electrical installations in hazardous areas (other than mines)

• EN 60079-19: 2007 – Explosive atmospheres. Equipment repair, overhaul and reclamation

• EN 60079-20: 2000 – Electrical apparatus for explosive gas atmospheres. Data for flammable gases 

and vapours, relating to the use of electrical apparatus 

• EN 60204-1: 2006 – Safety of machinery. Electrical equipment of machines. General requirements

• EN TR 14739: 2004 – Scheme for carrying out a risk assessment for flammable refrigerants in case of 

household refrigerators and freezers. BSI, London. 2004.

International standards

• DIS ISO 5149: 2009 – Mechanical refrigerating systems used for cooling and heating – Safety requirements

• IEC 60335-2-24: 2007 – Specification for safety of household and similar electrical appliances. 

Particular requirements for refrigerating appliances, ice-cream appliances and ice-makers

• IEC 60335-2-34: 2002 – Specification for safety of household and similar electrical appliances. 

Particular requirements for motor-compressors.

• IEC 60335-2-40: 2003 – Specification for safety of household and similar electrical appliances. Safety. 

Particular requirements for electrical heat pumps air-conditioners, and dehumidifiers

• IEC 60335-2-89: 2007 – Specification for safety of household and similar electrical appliances. Safety. 

Particular requirements for commercial refrigerating appliances with an incorporated or remote 

refrigerant condensing unit or compressor

• ISO 4126: 2004 – Safety Devices for Protection against excessive pressure

• ISO 4126-2: 2003 – Safety devices for protection against excessive pressure. Bursting disc safety 

devices

• ISO 817: 2005 – Refrigerants – designation and system classification

Industry guidance

• ACRIB. Guidelines for the safe use of HC refrigerants. Air Conditioning and Refrigeration Industry 

Board, London UK, 2000.

• Code of Practice 1 – Bulk LPG Storage at Fixed Installations - Liquefied Petroleum Gas Association 

(LPGA)

• Code of Practice 2 – Safe Handling and Transport of LPG in Road Tankers and Tank Containers by 

Road - Liquefied Petroleum Gas Association (LPGA)

• Code of Practice 3 – Prevention or Control of Fire Involving LPG - Liquefied Petroleum Gas

Association (LPGA)

• Code of Practice 7 – Storage of Full and Empty LPG Cylinders and Cartridges -Liquefied Petroleum 

Gas Association (LPGA)

• Code of Practice 24 – Use of LPG Cylinders - Liquefied Petroleum Gas Association (LPGA)

• Code of Practice 27 – Carriage of LPG Cylinders by Road - Liquefied Petroleum Gas Association 

(LPGA)

• Minimisation of Refrigerant Emissions from Refrigerating Systems – Institute of Refrigeration

• PD 6686:2006: Guidance on directives, regulations and standards related to prevention of fire and 

explosion in the process industries. British Standards Institution, London, UK

• Risk Assessments – British Refrigeration Association (BRA)
242

• Specifications including: “Jointing of Copper Pipework for Refrigeration Systems” – British 

Refrigeration Association (BRA)

• Safety Code of Practice for Refrigerating Systems Utilising A2/A3 Refrigerants – Institute of 

Refrigeration

Further reading

• ADL. Risk assessments of flammable refrigerants. Report for Calor Gas Ltd. Arthur D. Little, Cambridge, UK. 1998.

• Blom-Bruggeman, J. M, van Gerwen, R. J. M., Verwoerd, M. Risk Assessment of typical cooling and 

heating systems using natural working fluids. Part: Risk assessment methodology. R96-348. Report of 

TNO, Apeldoorn. Netherlands. 1996a.

• Blom-Bruggeman, J. M, van Gerwen, R. J. M., Verwoerd, M. Risk Assessment of a Bulk Milk Tank 

using Hydrocarbon Refrigerant. Final Report of TNO, Apeldoorn. Netherlands. 1996b.

• Cleaver, R. P., Marshall, M. R., Linden, P. F. The build-up of concentration within a single enclosed 

volume following a release of natural gas. J. Hazardous Materials, no. 36, pp. 209-226, 1994.

• Clodic, D., Cai, W. Study of diffusion of propane and iso-butane in rooms respecting the standardised 

practical limit. Proc. ASHRAE Annual Meeting, Boston, USA, 1997.

• Clodic, D., Cai, W. Tests and simulations of diffusion of various hydrocarbons in rooms from air 

conditioners and refrigerators. Proc. IIR Conf. Natural Working Fluids, Aarhus, Denmark, 1996. 

• Colbourne D., Safety of appliances using hydrocarbon refrigerants. In “Natural Refrigerants Sustainable Ozone- and Climate-Friendly Alternatives to HCFCs”, GTZ Proklima, Eschborn, Germany. 

2008.

• Colbourne, D, Suen, K. O., Risk analysis of flammable refrigerants, Part 1: Correlations for concentrations from leaks, Proc. 7th IIR Gustav-Lorentzen Conf., Copenhagen, Denmark. 2008.

• Colbourne, D, Suen, K. O., Risk analysis of flammable refrigerants, Part 2: Methodology for calculation of risk frequencies and flammable quantities, Proc. 7th IIR Gustav-Lorentzen Conf., Copenhagen, 

Denmark. 2008.

• Colbourne, D, Suen, K. O., Risk analysis of flammable refrigerants, Part 3: A simplified method for 

estimating the risk, Proc. 7th IIR Gustav-Lorentzen Conf., Copenhagen, Denmark. 2008.

• Colbourne, D., Suen, K. O. Appraising the Flammability Hazards of Hydrocarbon Refrigerants using 

Quantitative Risk Assessment Model. Part I: Modelling Approach. Int. J. Refrig., pp. 774 – 783, Vol. 

27. 2004

• Colbourne, D., Suen, K. O. Appraising the Flammability Hazards of Hydrocarbon Refrigerants using 

Quantitative Risk Assessment Model. Part II: Model evaluation and analysis. Int. J. Refrig., pp. 784 

– 793, Vol. 27. 2004

• Colbourne, D., Suen, K. O. Equipment design and installation features to disperse refrigerant releases 

in rooms. Part I: Experiments and analysis. Int. J. Refrig., No. 6, Vol. 26. 2003

• Colbourne, D., Suen, K. O. Equipment Design and Installation Features to Disperse Refrigerant 

Releases in Rooms. Part II: Determination of procedures. Int. J. Refrig., No. 6, Vol. 26. 2003

• Committee for the Prevention of Disasters (CPD). Guidelines for quantitative risk assessment of 

hazardous materials (liquids and gases). CPR-18E (Purple Book), 1st edition. The Hague, The Netherlands. 1999.

• Committee for the Prevention of Disasters (CPD). Methods for determining and processing probabilities. CPR-12E (Red Book), 1st edition. The Hague, The Netherlands. 1988.

• Committee for the Prevention of Disasters (CPD). Methods for the calculation of the physical effects 

due to releases of hazardous materials (liquids and gases). CPR-14E (Yellow Book), 3rd edition. The 

Hague, The Netherlands. 1997.

• Committee for the Prevention of Disasters (CPD). Methods for the calculation of consequences of the 

releases of hazardous materials (liquids and gases). CPR-16E (Green Book), 1st edition. The Hague, 

The Netherlands. 1992.

• Corberan, J. M., Segurado, J., Colbourne D., et al., Review of standards for the use of hydrocarbon 

refrigerants in A/C, heat pump and refrigeration equipment. Int. J. Refrig. Vol. 31, No. 4. 2008
243

• Elbers, S. J., Verwoerd, M. Quantitative Risk Assessment of a Heat Pump System with Propane 

Refrigerant. Final Report of TNO, R97-238. Apeldoorn, The Netherlands. 1997.

• Fletcher, B., Johnson, A. E. The accumulation of gases in ventilated and unventilated enclosures. 

Ventilation ’85, H. D. Goodfellow (Ed.), Amsterdam, 1986. 

• Gerwen, R. J. M., van, Jansen , C. M. A. Risk assessment of flammable refrigerants. Proc. IIR Conf. 

Natural Working Fluids, Hannover, Germany. 1994. 

• Gerwen, R. J. M., van, Koffijberg, H. Natural refrigerants: applications and risks. Proc. IIR 19th Int. 

Congr. Refrig. The Hague, The Netherlands. 1995. 

• Gerwen, R. J. M., van, Verwoerd, M. Quantification and evaluation of safety risks related to the use of 

ammonia and hydrocarbons as refrigerants. Proc. IEA Heat Pump Programme Annex 22 Workshop 

“Compression systems with natural working fluids”, HPP-AN22-3. October 1996. 

• Goetzler, W., Bendixen, L., Bartholomew, P. Risk assessment of HFC-32 and HFC-32/134a (30/70 

wt. %) in split system residential heat pumps. Final Report DOE/CE/23810-92 for ARTI, Arthur D. 

Little, USA. April 1998.

• Health and Safety Executive (HSE) information sheet, Use of LPG in small bulk tanks, Chemical 

Sheet No 4, October 1999, http://www.hse.gov.uk/pubns/chis4.pdf

• Health and Safety Executive (HSE). Reducing risks, protecting people. HMSO, Norwich, 2001.

• Jabbour, T. Clodic, D. Ignition tests of flammable refrigerant leaks in ventilated and unventilated 

rooms. Proc. 5th IIR Gustav-Lorentzen Conf., Guangzhou, China. 2002.

• Jansen, C. M. A., van Gerwen, R. J. M. Risk assessment of the use of flammable refrigerants. (In 

transport refrigeration.) R95-189. Final Report of TNO, Apeldoorn, Netherlands. 1996.

• Kataoka, O., Ishida, S., Hirakawa, T., Yoshizawa, M. Experimental and numerical analyses of refrigerant leaks in a closed room. ASHRAE Transactions, pp. 1151 - 1158, ASHRAE, Atlanta, USA. 2000b.

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refrigerants. Proc. Int. Refrig. Conf. Purdue, USA. 2000a.

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245

ABBREVIATIONS

AB Alkyl benzene

AC Air conditioning

ACRIB Air Conditioning and 

 Refrigeration Industry Board

ADR “Articles dangereuses par routier”

AHU Air handling unit

ARC AREA refrigeration craftsman/

 craftswomen

AREA Air Conditioning and Refrigeration 

 European Association

ATEL Acute toxicity exposure limit

ATEX “ATmosphère EXplosible” 

 (synonym for the European 

 ATEX-directive)

BMZ German Federal Ministry for 

 Economic Cooperation and 

 Development

BRA British Refrigeration Association

CE “Conformité européenne”

CEN “Comité européen de 

 normalization”

CENELEC “Comité européen de 

 normalisation electrotechnique”

CF Conversion factor

CFC Chlorofluorocarbon

CFD Computational fluid dynamics

CNS Central nervous system

COP Coefficient of performance

CPD Committee for the Prevention of 

 Disasters

CRE Carter Retail Equipment

DENA German Energy Agency

DGNB German Sustainable Building 

 Council

DN Diameter nominal

DOT (US) Department of 

 Transportation

DSEAR Dangerous substances explosive 

 atmospheres regulations

EC European Commission 

EN European norm

ESR Essential safety requirements

ETA Event tree analysis

EU European Union

FMCG Fast moving consumer goods

FMEA Failure modes and effect analysis

FTA Fault tree analysis

GHG Greenhouse gas

GTZ “Gesellschaft für technische 

 Zusammenarbeit“ (German 

 technical cooperation agency)

GWP Global warming potential

HazOp Hazard and operability study

HC Hydrocarbon

HCFC Hydrochlorofluorocarbon

HFC Hydrofluorocarbon

HPMP HCFC phase-out management 

 plan

HTF Heat transfer fluid

HUL Hindustan Unilever Limited

HVAC Heating, ventilating and air 

 conditioning

IATA International Air Transport 

 Association

IEC International Electro-technical 

 Commission

IMDG International maritime code for 

 dangerous goods

IMQ “Instituto italiano del marchio di 

 qualita”

ISO International Standardisation 

 Organisation

JCI Johnson Controls International

LFL Lower flammability limit

LPG Liquid petroleum gas

LPGA Liquid Petroleum Gas Association

MLF Multilateral Fund

NCG Non-condensable gases

NOU National ozone unit

ODL Oxygen deprivation limit

ODS Ozone depleting substances

OEM Original equipment manufacturer

OFDN Oxygen-free and dry nitrogen

PAG Polyalkyl glycol

PAO Polyalpha olefins

PE Pressure equipment

PED Pressure equipment directive

PL Practical concentration limit

POE Polyol ester

ppm Parts per million

PRV Pressure relief valve

PS Pressure

QC Quality control

QRA Quantitative risk assessment

QMS Quality management system

RAC Refrigeration and air 

 conditioning

SOI Sources of ignition

TDGR Transport of dangerous goods 

 regulation

TLV-TWA Threshold limit value – time 

 weighted average

TÜV “Technischer Überwachungsverein”

UFL Upper flammability limit

UN United Nations

UPS Uninterruptible power supply

V Volume

VDE „Verband der Elektrotechnik, 

 Elektronik und Informationstechnik“

VET Vocational and educational 

 training

VETC Vocational and educational training 

 centres

VTR Victorian transport refrigeration

WEEE Waste electrical and electronic 

 equipment
246

GLOSSARY

A5 Countries: Countries that are Party to the Montreal Protocol, listed under Article 5. These countries 

are permitted a ten-year grace period in the phase-out schedule in the Montreal Protocol compared with 

developed countries.

Accreditation body (quality control): A body that conducts and administers a laboratory accreditation 

system and grants accreditation. An accreditation body may wish to delegate fully or partially the 

assessment of a testing laboratory to another competent body (assessment agency). Whilst it is recognised that this may be a practical solution to extending recognition of testing laboratories, it is essential 

that such assessment be equivalent to that applied by the accreditation body and that the accreditation 

body take full responsibility for such extended accreditation.

Accredited laboratory (quality control): A laboratory is then accredited when it was accredited 

through a national recognised accreditation body for accreditation of test laboratories according to ISO/

IEC Guide or a national equivalent.

ADR (Articles Dangereuses par Routier): A regulation introduced in 2009 that should be referred to 

when transporting refrigerating machines by road and rail within Europe. 

Allowable charge size: The amount of refrigerant that is permitted to be used in a refrigerant circuit of a 

direct expansion system, usually based on the room size, so that a flammable concentration will be 

avoided in the event of a catastrophic leak.

Approvals body (quality control): A company specialising in testing and certification of engineers, 

test/quality engineers, design/development engineers, manufacturing/production engineers, engineering 

executive management and marketers.

Approved training organisation/awarding body (training): Organisation which is recognised on 

national level to assess competence and to award certificates (a proof of competence) recognising the 

health, safety, technical, environmental and energy conservation competence of persons working on 

refrigerating systems and heat pumps

Assessment (training): Process by which the evidence generated, gathered and provided about a person 

is judged to determine competence

ATEL (Acute-toxicity exposure limit): Describes the adverse effects of a substance which result either 

from a single exposure or from multiple exposures in a short space of time (usually less than 24 hours). 

To be described as acute toxicity, the adverse effects should occur within 14 days of the administration of 

the substance.

Brazing: A joining process whereby a filler metal or alloy is heated to a melting temperature above 

450°C and distributed between two or more close-fitting parts by capillary action.

Bulk tanks: A permanent or fixed location container for holding large quantities of refrigerant (or other 

fluid), typically of a volume of 2,000 litres, 4,000 litres or greater. 

Bund wall: A low-level wall usually surrounding containers with a flammable or otherwise dangerous 

fluid so that in the event of a spillage the release is better contained within a controlled area.

CE-certificate: A mark that certifies that a product has met EU consumer safety, health or environmental requirements. A notified body may be involved in the design phase, the production phase, or both, 

and the CE-marking shall only be followed by the identification number of the notified body. The 
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CE-mark is a visible declaration by the manufacturer (or his representative, importer, etc) that the 

equipment complies with all the requirements of all the applicable directives.

CEN (Comité Européen de Normalisation): A major provider of European Standards and technical 

specifications. It is the only recognized European organization according to Directive 98/34/EC for the 

planning, drafting and adoption of European Standards in all areas of economic activity with the 

exception of electrotechnology (CENELEC) and telecommunication (ETSI).

CENELEC (Comité Européen de Normalisation Electrotechnique): A non-profit technical 

organization set up under Belgian law and composed of the National Electrotechnical Committees of 

31 European countries. 

Certificate (training): Document issued under the rules of the assessment system indicating that the 

named person is competent to deal with applicable technologies, health, safety, environmental protection 

and energy conservation requirements for RAC system operating wit HC refrigerants.

Certification (training): Procedure used to demonstrate the qualification of personnel at a certain level 

and leading to the issue of a certificate.

Certification body (quality control): A body that conducts certification conformity. A certification 

body may operate its own testing and inspection activities.

CFC (chlorofluorocarbons): Halocarbons containing only chlorine, fluorine and carbon atoms; these 

are both ozone-depleting substances (ODSs) and greenhouse gases.

Charge: The term normally used to refer to the quantity or mass of refrigerant used in a circuit of a 

refrigerating system. 

Competence (training): Ability to perform safely and satisfactorily the activities within an occupation 

and with reference to this handbook to be competent means to have the knowledge and/or skill to 

perform the task(s) under consideration, so that a best possible level is achieved and simultaneously to 

possess the necessary insight into the relevant problems to understand why the task should be carried out 

in such a way. A person shall be deemed competent if it can be demonstrated that he is capable of 

carrying out the required activities.

COP (coefficient of performance): A measure of the energy efficiency of a refrigerating system, which 

is defined as the ratio between the refrigerating capacity and the power consumed by the system and 

primarily dependant on the working cycle and the temperature levels (evaporating/condensing temperature) as well as on the properties of the refrigerant, system design and size. (The comparable term “EER” 

or “energy efficiency ratio” is also used.)

Direct expansion system: A refrigerating system with one degree of separation from the occupied space, 

for example, an evaporator or condenser of the refrigerating system in contact with the air or the substance to be cooled or heated.

Emergency ventilation: A ventilation system (fans and ducting) used for extracting any build-up of 

flammable refrigerant within a room, enclosure or area in order to help mitigate the possibility of 

ignition; it is normally initiated by gas detection equipment.

ETA (event tree analysis): A logic-based technique, characterising the likelihood of hazards occurring 

according to contributing events not occurring or occurring. 
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First-party (quality control): First-party activities are carried out by manufacturers and suppliers. 

First-party testing is a large sector. It is for example used as an internal quality control measure that the 

products, materials, items and services are up the requirements expressed in legislation, standards, 

technical specifications and contracts with the clients. The manufacturers’ declaration of conformity 

expressed by different ways of marking the product is often based also on the outcome of these tests. In 

the fulfilment of conformity assessment requirements, for example those of the European directives, 

manufacturers must take all means necessary to ensure that the manufacturing process assures compliance with the prototype, to affix the CE marking to the product and to establish a technical documentation. For the purpose of complying with the related modules the manufacturer shall ensure that a quality 

system is implemented according to pertinent standards.

Flooded system: A refrigerating system that relies on a pool of boiling refrigerant to remove the heat 

from the heat transfer medium; this type of system usually requires significantly greater refrigerant than 

a so-called dry expansion type system, where the boiling refrigerant passes through the exchanger.

FMEA (failure modes and effect analysis): A method to primarily address the effects of failures or 

malfunctions of individual components within a system, with the objective of identifying which components are the most critical and thus, which require greatest consideration. 

FTA (fault tree analysis): a technique that combines a graphical approach and estimated probabilities 

to determine the likelihood of undesirable outcomes. It helps to systematically develop an overview of 

the possible events leading to one or more consequences. 

Functional testing: Testing the operation of a device or mechanism to check whether it operates as intended.

GHG (greenhouse gas): The gaseous constituents of the atmosphere, both natural and anthropogenic, 

that absorb and emit radiation within the spectrum of the thermal infrared radiation that is emitted by 

the Earth’s surface, by the atmosphere and by clouds. This property causes the greenhouse effect.

GWP (global warming potential): An index comparing the climate impact of an emission of a greenhouse gas relative to that of emitting the same amount of carbon dioxide. GWPs are determined as the 

ratio of the time integrated radiative forcing arising from a pulse emission of 1 kg of a substance relative 

to that of 1 kg of carbon dioxide, over a fixed time horizon. 

HazOp (hazard and operability study): Similar to a risk assessment technique in that it provides a 

useful means of gaining insight to the possible hazards posed by systems and installations, which can 

then be quantified by other means. 

HC (hydrocarbon): Chemical compounds consisting of one or more carbon atoms surrounded only by 

hydrogen atoms.

HCFC (hydrochlorofluorocarbons): Halocarbons containing only hydrogen, chlorine, fluorine and 

carbon atoms. Because HCFCs contain chlorine, they contribute to ozone depletion and they are also 

greenhouse gases.

HFCs (hydrofluorocarbons): Halocarbons containing only carbon, hydrogen and fluorine atoms. 

Because HFCs contain no chlorine, bromine or iodine, they do not deplete the ozone layer, but like 

other halocarbons they are potent greenhouse gases.

HPMP (HCFC phase-out management plan): A scheme comprising policy and technical elements 

that enable a country to phase out the consumption of HCFCs within the schedules prescribed within 

the relevant amendment to the Montreal Protocol.
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IATA (International Air Transport Association): An organisation which prescribes the Regulations 

for transport by air.

IEC (International Electrotechnical Commission): the world’s leading organization that prepares and 

publishes International Standards for all electrical, electronic and related technologies — collectively 

known as “electrotechnology”.

IMDG (International Maritime Dangerous Goods Code): A regulation introduced in 2008 which 

should be referred to when transporting refrigerating machines by sea.

Indirect system: A refrigerating system with more than one degree of separation from the occupied 

space, for example, where an evaporator cools or condenser heats the secondary heat transfer fluid (such 

as water or brine) which passes through closed circuit containing heat exchangers, that are in direct 

contact with the substance to be treated (such as air inside the occupied space).

ISO (International Organisation of Standardisations): the world’s largest developer and publisher of 

International Standards. 

Kyoto Protocol: The Kyoto Protocol to the United Nations Framework Convention on Climate Change 

(UNFCCC) was adopted at the Third Session of the Conference of the Parties (COP) to the UNFCCC 

in 1997 in Kyoto, Japan. It contains legally binding commitments, in addition to those included in the 

UNFCCC. Countries included in Annex B of the Protocol agreed to reduce their anthropogenic greenhouse-gas emissions (specifically carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6)) by at least 5% 

below 1990 levels in the commitment period 2008 to 2012. The Kyoto Protocol entered into force on 

16 February 2005.

LFL (Lower flammability limit): The lower end of the concentration range of a flammable solvent at 

a given temperature and pressure for which air/vapour mixtures can ignite. The flammability range is 

delineated by the upper and lower flammability limit. Outside this range of air/vapour mixtures, the 

mixture will not ignite (unless heated).

LPG (liquefied petroleum gas): A mixture of various hydrocarbons – typically propane and/or butane 

– which is normally used as a fuel gas for heating and cooking. The composition of LPG normally 

incidentally includes moisture, sulphur and other substances not normally suitable for use in refrigerating systems.

Machinery room: An enclosed room or space, vented by mechanical ventilation, sealed from public 

areas and not accessible to the public, which is intended to contain components of the refrigerating 

system.

Maximum charge size: The upper limit of the quantity of refrigerant than can be used in a particular 

type of system and occupancy. 

MLF (Multilateral Fund): A fund established in 1991 to assist A5 countries in meeting their Montreal 

Protocol commitments, through financing activities including industrial conversion, technical assistance, 

training and capacity building.

MSDS (materials safety data sheet): A safety advisory bulletin prepared by chemical producers or 

suppliers for a specific refrigerant or compound.
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Montreal Protocol on Substances that Deplete the Ozone Layer: Adopted in Montreal in 1987 and 

subsequently adjusted and amended in London (1990), Copenhagen (1992), Vienna (1995), Montreal 

(1997) and Beijing (1999). It controls the consumption and production of chlorine- and bromine-containing chemicals, known as ozone depleting substances (ODSs) that destroy the stratospheric ozone layer.

NCGs (non-condensable gases): Gaseous contaminants sometimes found inside a refrigerating system, 

often nitrogen and oxygen due to migration from the air, which collect within the high side a system and 

impedes its performance. 

Notified body (quality control): A Notified Body is an organisation that has been nominated by a 

member of Government and notified by the European Commission (as sample). A Notified Body will 

be nominated based on designated requirements, such as knowledge, experience, independence and 

resources to conduct the conformity assessments. The primary role of a Notified Body is to provide 

services for conformity assessment on the conditions set out in the New Approach Directives in support 

of CE Marking. This normally means assessing the manufacturers conformity to the essential requirements listed in each directive. Conformity assessment can be inspection, quality assurance, type examination or design examination, or a combination of these.

Novel testing: Where some unusual issue has to be addressed and no specific test procedures exist 

within standards or other guidelines which must otherwise be followed. Example of this may arise 

during the development of a new type of safety device or where a hitherto unanticipated set of 

circumstances has arisen.

Occupancy category: The type of category that is occupied by persons, necessary for the determination 

of safety design requirements for the refrigerating system; either A (e.g., public), B (e.g., private) or C 

(e.g., authorised personnel).

Occupied space: Space bounded by walls, floors and ceilings in buildings which are occupied for a 

significant period by persons.

ODL (oxygen deprivation limit): Concentration of a refrigerant or other gas that results in insufficient 

oxygen causing the onset of abnormal.

ODP (ozone depletion potential): A relative index indicating the extent to which a chemical product 

may cause ozone depletion compared with the depletion caused by CFC-11. Specifically, the ODP of an 

ozone depleting substance (ODS) is defined as the integrated change in total ozone per unit mass 

emission of that substance relative to the integrated change in total ozone per unit mass emission of 

CFC-11.

ODS (ozone depleting substance): Substances known to deplete the stratospheric ozone layer. The 

ODSs controlled under the Montreal Protocol and its Amendments are chlorofluorocarbons (CFCs), 

hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, methyl chloroform, 

hydrobromofluorocarbons and bromochloromethane.

OFDN (oxygen free dry nitrogen): Refrigeration-grade nitrogen used for working on refrigeration 

systems, that minimises the potential for contamination of the inside of the system with air, moisture or 

other contaminants.

PL (practical concentration limit): Another measure for the application of refrigerants. This represents 

the highest concentrations level in an occupied space which will not result in any escape impairing (i.e. 

acute) effects. Thus, it is principally, the lowest “dangerous” concentration of a refrigerant, with a safety 

factor applied.
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QC (quality control): A procedure or set of procedures intended to ensure that a manufactured or 

installed product, service or some other process adheres to a defined set of quality criteria or meets 

certain requirements. Examples of this include safety testing, third party inspections and quality marking. 

QMS (quality management system): A system used to assess the principles and processes surrounding 

the design, development and delivery of a general product or service.

QRA (quantitative risk assessment): A method used to numerically evaluate the probability of a 

particular hazard occurring, such as the likelihood of an occurrence of ignition of a flammable gas and 

the severity of the consequences, normally drawing on statistical and empirical data of the contributing 

events.

Qualification (training): The evidence of a certain level of professional competence. Any involved 

person shall demonstrate a level of predefined competence of theoretical and/or practical ability as 

necessary for the activity in question.

Refrigerant: A fluid used for heat transfer in a refrigerating system, which absorbs heat at a low temperature and a low pressure of the fluid and rejects it at a higher temperature and a higher pressure of the 

fluid usually involving changes of the phase of the fluid.

Refrigerating system: A combination of interconnected refrigerant-containing parts constituting one 

closed circuit in which the refrigerant is circulated for the purpose of extracting and rejecting heat (i.e., 

heating and cooling).

Sealed system: Refrigerating system in which all refrigerant containing parts are made tight by welding, 

brazing or a similar permanent connection (this may include capped valves and/or capped service 

valves).

Second-party (quality control): Second-party activities are performed by buyers, users or consumers. 

Second-party testing is performed by the receiver of the products, materials, items and services mainly in 

order to ensure that agreed requirements and specifications are fulfilled. For ordinary consumers, testing 

can be performed by consumer interest organisations or buyer organisations of products. Because of its 

often very individual nature this type of testing is not considered in detail here.

SOI (source of ignition): An electrical or other device that is capable of igniting a mixture of flammable refrigerants and air, within its flammable limits. 

TDGR (United Nations Model Regulations for Transport of Dangerous Goods): A regulation 

introduced in 2007 that should be referred to when transporting refrigerating machines by road and rail 

outside Europe. Equipment containing less than 12 kg is exempt from the regulations provided it is 

protected by design. For equipment containing over 12 kg, it must be subject to a pressure type-test of at 

least three times the maximum working pressure and comply with the packaging requirements detailed 

in these regulations. 
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Third-party (quality control): Third-party activities done by organisations independent of the above 

mentioned parties. A third-party is a person or body that is recognised as being independent of the 

parties involved, as concerns the issue in question. Third-party testing is especially required, preferred or 

used if the results have a considerable influence or effect on public or societal issues, in particular related 

to health, environment, safety and large economic values. It is also applied when taking measures to 

eliminate the possibility of cheating and considerable misconduct or when crucial risks and consequences 

of wrong or manipulated results exist. Third-party testing is expected to provide a non-biased view and 

thus a better confidence in the test results.

TLV-TWA (threshold limit value – time weighted average): average exposure on the basis of an 8 

hour per day, 40 hour per week work schedule.

Type-testing: Rigorous test that is applied to something that this normally tested routinely, in order to 

check that an assumed higher level of safety is still inherent in the design or process. Examples include 

high pressure destructive testing or observing the behaviour of an item within a fire situation.

VETC (vocational and educational training centres): An educational establishment that prepares 

trainees for jobs that are based on manual or practical activities, traditionally non-academic, and totally 

related to a specific trade, occupation, or vocation.
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Refrigerant 

number

Chemical or 

composition*

Molecular 

mass 

(kmol/kg)

Critical 

temperature 

(°C)

Normal 

boiling point 

(°C)

Vapour 

pressure at 

30°C (kPa)

R170 ethane (C2H6) 30.1 32.2 -88.6 4704

R290 propane (C3

H8) 44.1 96.7 -42.1 1092

R433A R1270/R290 (30%/70%) 43.5 94.2 -44.5 1178

R433B R1270/R290 (5%/95%) 44.0 96.3 -42.6 1108

R433C R1270/R290 (25%/75%) 43.6 94.6 -44.2 1165

R436A R290/R600a (56%/44%) 49.3 115.9 -34.3 768

R436B R290/R600a (52%/48%) 49.9 117.4 -33.4 741

R290/R600a (50%/50%) 51.1 120.7 -31.0 814

R290/R170 (94%/6%) 43.3 94.2 -49.0 1393

R50 methane (CH4

) 16.0 -82.6 -161.5 [super critical]

R600 butane (C4

H10) 58.1 152 -0.5 288

R600a isobutane (C4

H10) 58.1 134.7 -11.7 410

R601 pentane (C5

H12) 72.2 196.6 36.1 83

R601a isopentane (C5

H12) 72.2 187.2 27.8 111

R1150 ethylene (C2H4) 28.1 9.2 -103.8 [super critical]

R1270 propylene (C3

H6) 42.1 91.1 -47.6 1321

*Compositions in molar percent

APPENDICES

APPENDIX 1: NON-SAFETY RELATED TECHNICAL ASPECTS

Introduction 

There are several HCs that may be used as refrigerants. R600a (iso-butane) and R290 (propane) are the 

most widely used in non-industrial applications. In addition to these, R1270 (propylene), and two sets of 

blends are also used. There are several mixtures of R600a and R290 and another is a mixture of R290 

and R170, although the compositions for these vary by producer. There are also mixtures of R290 and 

R1270. For industrial applications, a variety of other HCs are used, including R50 (methane), R170 

(ethane), R601 (pentane), R601a (isopentane) and R1150 (ethylene). Table 21 provides a list of HC 

refrigerants and some basic properties.

Table 21: HC refrigerants and basic properties
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Refrigerant purity

Refrigerant grade product should be used for all RAC systems. Commercial grade HCs (e.g. liquefied 

petroleum gas, short cut LPG) contains significant quantities of sulphur, water, and other impurities and 

could contribute to oil degradation, shorten compressor life and invalidate warranties. The composition 

of commercial LPG is variable so the thermodynamic properties of the fluid may vary significantly from 

cylinder to cylinder. Also, unlike commercial LPG, HC refrigerants are not odorised.

Material compatibility

It is important to consider the compatibility of the refrigerant and the compressor oils with system 

materials such as plastics, elastomers, metals, etc. Virtually all common elastomer and plastic materials 

used as ‘O’ rings, valve seats, seals and gaskets are compatible with HC refrigerants. Materials that are 

not compatible and should not be used in HC systems include EPDM, natural rubbers and silicone 

rubbers. It should be noted that, chloroprene (neoprene) products are specifically incompatible with 

unsaturated HCs (i.e., R1270, R1150). Whilst testing has been conducted on a number of selected 

materials with refrigerant and oil combinations it should be noted that there are numerous different 

grades available in the market and for this reason compatibility should be checked with the manufacturer or supplier of the component. Normally component suppliers will be available to confirm whether 

or not the used materials pose a compatibility problem.

Lubricants

Most common refrigeration oils are also compatible with HCs, although there is often high solubility 

with certain mineral and POE oils. However, various lubricant manufacturers provide refrigeration oils 

specifically for HC refrigerants. An overview of the suitability of HCs with various lubricants is provided 

in Table 22.

Table 22: Compatibility and solubility of different oils with HCs

Thermo-physical characteristics and transfer process

Thermodynamic and transport properties of refrigerants affect the design and performance of the 

refrigerating system. The most important properties are vapour pressure as this is a common factor used 

in selecting a particular refrigerant for a given type of system and application. HCs have a much lower 

molecular mass than the commonly used CFCs, HCFCs and HFCs, and these result in some differences 

in their thermophysical properties and therefore their operating characteristics.

Vapour pressure

The group of HCs cover a broad range of vapour pressures, suitable for most RAC applications. Certain 

HCs are blended in order to achieve certain other vapour pressures. Over the range of vapour pressures 

offered by common CFC, HCFC and HFC refrigerants, there is a comparable set of HC refrigerants, as 

Oil type Compatibility Solubility

Mineral Oil (MO) Good High

Alkyl benzene (AB) Good Medium

Polyol Ester (POE) Good High

Poly alpha oelfin (PAO) Good High

Poly alkyl glycol (PAG) Good Medium
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indicated in Table 23. A particular characteristic of HC refrigerants is that the slope of the vapour 

pressure curve with respect to temperature tends to be ‘flatter’ than with the CFCs, HCFCs and HFCs, 

and this results in a lower compression ratio (for the same operating saturation temperatures).

Table 23: Comparable HC refrigerants for replacing ODS and HFC refrigerants*

Volumetric refrigerating effect

The volumetric refrigerating effect of the HCs whose vapour pressure corresponds to that of CFCs, 

HCFCs and HFCs also tend to provide similar volumetric refrigerating effects (also implicit in Table 3). 

Although the latent heat of HCs is approximately double that of the CFCs, HCFCs and HFCs, the 

vapour density is about half, thus resulting in similar refrigerating effect. 

Discharge temperature

HCs have a fairly high specific heat capacity and therefore the compressor discharge temperature tends 

to be lower than for most CFCs, HCFCs and HFCs, based on a similar set of operating conditions. 

Pressure loss

HCs have a fairly low density and low viscosity, which results in a smaller frictional pressure loss than 

may be experienced with common CFCs, HCFCs and HFCs (for a given refrigerating capacity). This is 

relevant to both single phase liquid and vapour flows, and two-phase flow.

Heat transfer

HCs have a fairly high thermal conducted and low viscosity, which results in a higher convective heat 

transfer coefficient than may be achieved with most common CFCs, HCFCs and HFCs (for a given 

refrigerating capacity). This trend is applicable for single phase liquid and vapour flows, as well and 

two-phase flow. However, for pool boiling HCs have no significant benefit over other refrigerants.

Charge size

The density of HCs is around half that of CFCs, HCFCs and HFC, therefore the corresponding charged 

refrigerant mass is normally less than 50% of that required for other refrigerants.

Equipment cost implications

For given refrigerating system, the main cost implication is the requirement for no sources of ignition, 

which generally translates as the avoidance of sparking electrical components. Under certain conditions, 

this can be achieved by repositioning the vulnerable components, thus resulting in no cost variation. 

ODS refrigerant HFC refrigerant HC refrigerant

R600a

R12 R134a R436A, R436B, R290/R600a

R502 R404A, R507A R290, R1270, R433A, R433B, R433C, R290/R170

R22 R407C R290, R1270, R433A, R433B, R433C, R290/R170

R410A

R13, R503 R23 R170

R11, R123 R236ea, R236fa, R245fa R601, R601a

*Comparable in terms of operating pressure/temperatures and cooling capacity
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For other circumstances, existing electrical components may need to be replaced with, for instance, low 

current/low voltage components or sealed/encapsulated devices. In these cases, the level of additional 

cost is sensitive to the type of equipment and the number and types of electrical devices associated with 

it, and a cost evaluation can only be carried out on a case-by-case basis. With larger systems that necessitate the use of a flammable gas detector and associated emergency ventilation, the add-on cost can be 

somewhat higher. With respect to non-safety aspects, it is often the case that smaller interconnecting 

pipework, evaporator and especially condenser tubes can be used whilst maintaining the same system 

cooling capacity and efficiency, means that less copper is required to construct the system, leading to a 

cost reduction. Manufacturers have found that when a thorough technical analysis is carried out, 

product cost can be less than with HCFC and HFC models.

Common applications

Other than industrial refrigeration, there has been refrigeration, air conditioning and heat pump equipment produced using HCs in a wide variety of equipment, including:

• Domestic refrigeration

• Small commercial refrigeration appliances

• Supermarket systems (using indirect circuit to the occupied areas)

• Small portable and single split air conditioners

• Water-to-water heat pumps

• Air conditioning and refrigeration chillers

• Refrigerated trucks

By far the most extensive application is domestic refrigeration, although small commercial refrigeration 

systems are also expanding rapidly, and water-to-water heat pumps previously had a large market share. 

There are a number of reasons for the limited application in other types of systems, of which there are 

two general cases. The first is the insufficient political (legislative) drivers to force manufacturers and 

contractors to overcome the inertia caused by the additional issues to deal with then adopting a flammable refrigerant. The second is the reluctance of many compressor manufacturers to permit their compressors to be used with flammable refrigerants (for example now in the case of water-to-water heat pumps), 

and other similar commercial influencing factors. 

There is a large and realistic potential for HCs to replace HCFCs and HFCs in a variety of targeted 

system types. The categories that are applicable are those listed above (except domestic refrigeration), 

where experience has already been gained. Taking into consideration the aspects highlighted above, there 

is potential for HCs to be used, or used more widely in a number of situations.

Domestic refrigeration

Approximately one third to one half of domestic refrigerators is currently manufactured using HCs, 

primarily R600a, and its use is continuing to increase, for example, in South America. The reason for 

the remaining portion still using HFC-134a is mainly due to the manufacturers not seeing the need to 

shift production from one technology to another, whilst in certain regions (e.g. North America) the 

potential for legal implications of using a flammable refrigerant are considered too risky to offset the 

environmental and/or marketing arguments. There are no technical reasons why HCs cannot be used 

for the large majority of the sector; with certain models, it may be necessary to use specific components 

suitable for flammable atmospheres, which can increase the cost of the product.

Commercial refrigeration

In terms of the types of systems used within the commercial refrigeration sector, integral (stand-along), 

remote (condensing units) and centralised systems must be considered separately. In terms of integral 

systems, the issues are similar for domestic refrigerators; there is a continued growth in the use of R600a 

and R290 in a variety of different appliances, for vending machines, bottle coolers, freezers, kitchen 
257

storage cabinets, etc. For the majority of products, HCs can be widely applied, particularly given that 

there are international safety standards that permit their application. For the larger systems that require 

larger refrigerant charge sizes, the use of HCs is restricted to regions where safety standards are currently 

in place (for example, but not exclusively, Europe, Australia/New Zealand, Indonesia).The widespread 

adoption of these standards would enable to use of HCs in larger systems across a greater extent, in a 

large proportion of equipment. For remote systems, charge sizes are often large and typically extend to 

various parts of a building. Thus, whilst the application of HCs is technically possible, and may be 

possible within the scope of safety standards, it is complicated and must be handled on an individual 

basis. For this reason, the use of HCs in remote systems is minimal, and is unlikely to be a technology of 

choice. For the same reasons as with remote systems, HCs cannot be used in conventional centralised 

pack/rack type systems. Instead, many central systems in Europe and elsewhere use HCs within a central 

chiller (located in a machinery room or outside) to cool a secondary refrigerant (brine, glycol, carbon 

dioxide), which is circulated to display cases and coldstores. As supermarkets shift to alternative systems, 

the use of central HC chillers is a viable option and has the potential to be used in the large majority of 

systems. 

Industrial refrigeration 

Industrial refrigeration covers a wide range of applications, including food processing, cold storage, 

process refrigeration, liquefaction of gases, and industrial heat pumps and heat recovery. HCs are not 

often used in many of these sub-sectors, although they are fairly wisely applied in process refrigeration; 

specifically chemical and petro-chemical processes. Since the majority of these systems are bespoke 

construction, it is difficult to provide general rules in terms of technical, cost, safety or legislative 

implications of applying HCs. 

Transport refrigeration

Transport refrigeration can be broadly divided into reefer ships, intermodal refrigerated containers, 

refrigerated railcars and refrigerated trailers/trucks. Of these, HCs have been applied within refrigerated 

trucks and trailers. There are no technical reasons for why they cannot be applied widely in road transport systems, and the additional safety measures are not prohibitive (for example, use of a gas detector 

and warning alarm). The primary restriction is the possible legislation in certain countries that may 

prevent flammable refrigerants being used widely. The use of HCs is not considered for use in reefer 

ships or intermodal containers and railcars. However, due to the unusual nature of the applications, it is 

difficult to make broad statements without further consideration.

Air conditioners and heat pumps 

Air conditioners can be divided into window, portable, single split, ducted and multi-split units. R290 

has been applied in portable units and single split systems for at least 10 years, in Europe, Australasia 

and more recently are being produced in China. Due to charge size limitations ducted and multi-split air 

conditioners are not suitable for use with HCs. Whilst there are no technical or legislative reasons for 

why HC cannot be more widely applied to window, portable and single split air conditioners, recent 

changes to safety standards have introduced more restrictive limits on charge sizes, meaning that special 

attention has to be paid to redesigning existing models for much lower refrigerant charges. However, in 

certain situations, this can actually lead to a reduction in equipment cost. Overall, for the smaller sized 

air conditioning sector, a large portion could easily adopt HCs. 

Water-heating heat pumps

Water heating heat pumps are typically small and medium sized appliances used in dwellings and 

commercial buildings for providing hot water and central heating. For small domestic water heating heat 

pumps, R290 has been widely used within Europe. Since 2002, its use has declined due to the introduction of the Pressure Equipment Directive (PED), which necessitated the approval of the preferred types 

of compressors for use with HC refrigerants. Since most of the compressor manufacturers had a policy 

against use of HCs in larger systems, approvals were not forthcoming and the use of R290 in these types 
258

of systems became limited. Apart from this legislatively-orientated hindrance, there are no technical 

reasons why R290 cannot be applied widely across this sector, particularly since they are self-contained 

systems and can be easily designed to meet safety requirements. 

Air conditioning chillers

Air conditioning chillers may be divided into positive displacement and centrifugal machines, and cover 

a wide range of capacity sizes. They may be located within building basements, in machinery rooms, in 

enclosures outside buildings or on building roofs. Currently, there are no (non-industrial) centrifugal 

chillers using HCs, although several companies within Europe and other regions are producing small 

and medium sized scroll, reciprocating and screw chillers using R290 and R1270. These are typically 

positioned outside (besides the building or on the roof) and also within machinery rooms, although this 

can invoke additional costs because of the extra safety measures. HC chillers cannot be located below 

ground, which limits their widespread application. Otherwise, there are no technical problems with their 

application, and generally the cost impact of adopting HCs is minimal (except for economies of scale). It 

is possible that HCs could be used in over 80% of small and medium sized chiller applications. 

Vehicle air conditioning

Vehicle air conditioning includes car, bus, rail, truck and air transport air conditioning. Presently, HCs 

are not applied in new systems for any of these uses, and in fact their use in aviation air conditioning is 

not viable because of safety issues. Whilst HCs have been used to a limited extent as a retrofit refrigerant 

in bus air conditioning, it is unsuitable due to the high refrigerant charge sizes. Similar issues probably 

apply to rail car and truck air conditioning. Despite the extensive application of HCs as retrofit refrigerants in car air conditioning in certain regions, their application in new systems is unlikely to materialise 

due to the current focus on the other candidate options, such as R744 (carbon dioxide) and unsaturated 

HFCs. 
259

APPENDIX 2: EXAMPLE CONVERSION PROCEDURES

Introduction

This Appendix is intended to complement the information provided within Part 6.4 of the handbook. 

There are too many occasions where systems are found to have been converted from HCFCs or HFCs 

straight to HCs without proper care and attention and consideration given to ensuring that the system is 

left in the correct state where it conforms to the appropriate safety standards. These situations are 

dangerous and not acceptable. 

It is acknowledged that conversions of equipment will take place, and whilst there are disagreements as 

to this taking place, it was considered important to provide detailed information on the correct manner 

by which a conversion should be carried out, including some pictorial, step-by-step example. If a conversion is considered, then the situation must be analysed, and if it is decided to take place it must be 

carried out to include all the relevant stages as described in Part 6.4 and as illustrated below. 

Conversion of split air conditioner

Identify problem with air conditioner

1) Obtain current charge size

g 1.3 kg of R22

2) Estimate equivalent HC charge

g Assuming conversion to R290, 

1.3 × 0.42 = 0.54 kg of R290

3) Identify occupancies

g Outdoor unit is in well 

ventilated area, authorised 

access only (category C)

g Indoor unit within office 

(category B)

4) Check charge size limits

g Charge size is below 

maximum limit (0.54 kg < 1 kg)

g Room size is 6 m × 9 m = 54 

m2

, so below allowable charge 

(0.54 kg < 0.56 kg)

5) Check all necessary tools are present and the working area is safe

g Okay

TABLE USED FOR SCREEN-GRAB FOR “Conversion of split air conditioner”

Conversion factors ( ) to estimate equivalent HC charge size 

HC refrigerant

Fluorinated 

refrigerant R600a R600a/R290 

(50%/50%) R290 R290/R170

(94%/6%) R1270

CFC-12 (0.43) † 0.40 n/a n/a n/a

HFC-134a (0.47) † 0.45 n/a n/a n/a

HFC-1234yf (0.53) † 0.50 n/a n/a n/a

HCFC-22 n/a n/a 0.42 0.41 0.42

HFC-407C n/a n/a 0.45 0.44 0.45

HFC-404A n/a n/a 0.51 0.50 0.52

HFC-507A n/a n/a 0.51 0.50 0.52

HFC-410A n/a n/a (0.51) † (0.50) † (0.52) †

TABLE USED FOR SCREEN-GRAB FOR “Conversion of commercial cabinet”

Conversion factors ( ) to estimate equivalent HC charge size 

HC refrigerant

Fluorinated 

refrigerant R600a R600a/R290 

(50%/50%) R290 R290/R170

(94%/6%) R1270

CFC-12 (0.43) † 0.40 n/a n/a n/a

HFC-134a (0.47) † 0.45 n/a n/a n/a

HFC-1234yf (0.53) † 0.50 n/a n/a n/a

HCFC-22 n/a n/a 0.42 0.41 0.42

HFC-407C n/a n/a 0.45 0.44 0.45

HFC-404A n/a n/a 0.51 0.50 0.52

HFC-507A n/a n/a 0.51 0.50 0.52

HFC-410A n/a n/a (0.51) † (0.50) † (0.52) †
260

Conversion of split air conditioner

Identify problem with air conditioner

6) Eliminate all mechanical joints 

from occupied space

g Okay

7) Reset pressure device g none

8) Eliminate all potential sources 

of ignition

g Inside unit: transformer, 

display/ LED, swing motors, fan 

motor, connection block, PCB 

(relays, micro switch) – all 

non-SOIs

g Outdoor unit: – fan motor, 

capacitors, connection block, 

compressor terminals (internal 

overload) – all non-SOIs, although 

mains contactor must be fitted 

into sealed enclosure

9) Set-up emergency ventilation/detection and alarm system

g Not applicable

10) Carry out relevant repairs 

g Okay

11) Apply relevant documentation 

and system markings

12) Final leak checking

g Okay
261

Conversion of commercial cabinet

Identify problem with cabinet

1) Obtain current charge size

g 0.285 kg of R12

2) Estimate equivalent HC charge

g Assuming conversion to 

R600a/R290 blend, 0.285 × 0.40 = 

0.114 kg of R290

3) Identify occupancies

g Cabinet positioned within retail 

area (category A)

4) Check charge size limits

g Charge size is below maximum limit (0.11 kg < 1.5 kg)

g Charge size is below 0.15 kg, so no need to consider allowable charge or room size

5) Check all necessary tools are 

present and the working area is 

safe

g Okay

6) Eliminate all mechanical joints from occupied space

g None present

7) Reset pressure devices

g None

TABLE USED FOR SCREEN-GRAB FOR “Conversion of split air conditioner”

Conversion factors ( ) to estimate equivalent HC charge size 

HC refrigerant

Fluorinated 

refrigerant R600a R600a/R290 

(50%/50%) R290 R290/R170

(94%/6%) R1270

CFC-12 (0.43) † 0.40 n/a n/a n/a

HFC-134a (0.47) † 0.45 n/a n/a n/a

HFC-1234yf (0.53) † 0.50 n/a n/a n/a

HCFC-22 n/a n/a 0.42 0.41 0.42

HFC-407C n/a n/a 0.45 0.44 0.45

HFC-404A n/a n/a 0.51 0.50 0.52

HFC-507A n/a n/a 0.51 0.50 0.52

HFC-410A n/a n/a (0.51) † (0.50) † (0.52) †

TABLE USED FOR SCREEN-GRAB FOR “Conversion of commercial cabinet”

Conversion factors ( ) to estimate equivalent HC charge size 

HC refrigerant

Fluorinated 

refrigerant R600a R600a/R290 

(50%/50%) R290 R290/R170

(94%/6%) R1270

CFC-12 (0.43) † 0.40 n/a n/a n/a

HFC-134a (0.47) † 0.45 n/a n/a n/a

HFC-1234yf (0.53) † 0.50 n/a n/a n/a

HCFC-22 n/a n/a 0.42 0.41 0.42

HFC-407C n/a n/a 0.45 0.44 0.45

HFC-404A n/a n/a 0.51 0.50 0.52

HFC-507A n/a n/a 0.51 0.50 0.52

HFC-410A n/a n/a (0.51) † (0.50) † (0.52) †
262

Conversion of commercial cabinet

Identify problem with cabinet

8) Eliminate all potential sources 

of ignition

g Front of unit: fan motor, lamp 

– all non-SOIs; light switch, 

thermostat, lamp starter – all 

outside cabinet away from refrigerant-containing parts so a leak 

cannot reach them

g Rear of unit: – fan motor, 

capacitors, connection block, 

compressor terminals (internal 

overload) – all non-SOIs; overload/relay must be swapped with 

solid-state type

9) Set-up emergency ventilation/detection and alarm system g Not applicable

10) Carry out relevant repairs g Okay

11) Apply relevant documentation 

and system markings

12) Final leak checking

g Okay

Disclaimer

Whilst GTZ and TÜV SÜD do not condone the conversion of existing equipment using non-flammable refrigerant to use 

flammable refrigerants that they were not initially intended for, they do recognise that such conversion do and will continue to 

take place, regardless of recommendations to the contrary. Therefore, in order to try to help that it is done in the safest manner, 

some examples are provided in the Appendix. However, in doing this, GTZ and TÜV SÜD do not assume liability for any 

statements or any actions taken by its readers or users, which may cause unintended damage or injury as a result of any recommendations or inferences made within this handbook. Although all statements and information contained herein are believed 

to be accurate and reliable, they are presented without guarantee or warranty of any kind, expressed or implied. Information 

provided herein does not relieve reader or user from their responsibility of carrying out its own evaluation and analysis of the 

situation, and reader or user assumes all risks and liability for use of the information, actions and events obtained. Reader or 

user should not assume that all safety data, measures and guidance are indicated herein or that other measures may not be 

required. Here only general recommendations are made, which do not compensate for individual guidance and instructions. 

National laws and guidelines must be consulted and adhered to under all circumstances. The handling of flammable refrigerants and its associated systems and equipment is to be done by qualified and trained technicians only. 
263

APPENDIX 3: LIST OF COOPERATION PARTNERS

Please refer to Part 1.4 of this handbook “Identification of Cooperation Partners” for more information. 

Links are given where available for the cooperation partners listed below.

Industry associations

Brazilian Association of Refrigeration, Air Conditioning, Ventilation and Heating (ABRAVA)

(www.abrava.com.br)

ABRAVA is the main trade associations within Brazil that represents the refrigeration and air conditioning industry. 

Association of European Refrigeration Compressor and Controls Manufacturers (ASERCOM)

(www.asercom.org) 

It is the aim of ASERCOM to be the platform in dealing with scientific and technical challenges, 

promoting standards for performance and safety while focusing on better environmental protection and 

serving the refrigeration and air conditioning industry and its customers.

Associated Air conditioning and Refrigeration Contractors (ARC) (www.arc-uk.org.uk) 

ARC is a nationwide organisation of selected air conditioning and refrigeration contractors who are 

privately owned and funded and whose primary aim is to provide good quality service. Our aim is to 

maintain the very highest standards in design, installation and after-sales service, but more than this, we 

are active in promoting energy conservation and maximum plant efficiency. It is the firm belief of our 

organisation that a satisfied client is the greatest asset any business can possess.

Air Conditioning and Refrigeration Industry Board (ACRIB) (www.acrib.org.uk)

ACRIB provides a central forum for all sectors and interests which fall within or are served by the air 

conditioning and refrigeration industry. Its member organisations represent manufacturers, distributors, 

contractors, consulting engineers, specifies, end users, training providers, researchers and others with a 

direct interest in the environmentally friendly and cost effective provision and use of refrigeration, air 

conditioning and mechanical ventilation equipment.

Association of Manufacturers of Domestic Appliances (AMDEA) (www.amdea.org.uk) 

AMDEA is the trade association for large and small domestic appliances in the UK. The membership 

consists of companies who place domestic appliances on the UK market either as manufacturers, distributors or importers. It represents over 80% of the domestic appliances industry in the UK.

China Refrigeration and Air Conditioning Industry Association (CRAA) (www.chinacraa.org) 

CRAA is a national non-profit industrial organisation mainly representing refrigeration and air 

conditioning manufacturers, and research, design institutes and academies as well, with the principal 

of voluntarily participation. CRAA is a major voice for the whole industry and works for its members’ 

mutual interests and benefits.

Eurammon (www.eurammon.com) 

eurammon is a joint initiative by companies, institutions and individuals committed to increasing the 

use of natural refrigerants and sees itself as centre of competence for the use of natural working fluids in 

refrigeration. The objective is to boost the general awareness and acceptance of natural refrigerants, to 

promote their use in the interests of a healthy environment, and to thereby continue developing a 

sustainable approach to refrigeration.
264

European Federation of Refrigeration and Air Conditioning Associations (AREA)

(www.area-eur.be) 

AREA is the European Federation of National Refrigeration and Air Conditioning Associations and 

covers all of Europe. Established in 1988, AREA represents the industry of refrigeration and air conditioning installation, particularly at European Commission (EC) and the United Nations Environmental 

Programme (UNEP) level.

European Heat Pump Association (EHPA) (www.ehpa.org) 

The European Heat Pump Association promotes awareness and proper deployment of heat pump 

technology on the European market.

Federal Guild of German Refrigeration Plant Assemblers (BIV) (www.biv-kaelte.de) 

The BIV represents enterprises responsible for the design, installation, maintenance and repair of 

refrigeration equipment. It supports the interests of its members in the skilled crafts of refrigeration plant 

construction in accordance with legal requirements. As a member of the Central Guild of German 

Trades (ZHD), BIV develops the political, national and commercial environment of its own trade. 

Traditionally, the work of the guilds and BIV focuses mainly on the professional trade. The objective of 

BIV is to increase the expertise of its member companies in terms of technological, design and commercial quality and to create a positive public image for the refrigeration trade.

Federation of Environmental Trade Associations (FETA) (www.feta.co.uk) 

FETA is the recognised UK body which represents the interests of manufacturers, suppliers, installers 

and contractors within the heat pump, controls, ventilating, refrigeration & air conditioning industry. It 

is split into six principle associations ADCAS, BCIA, BFCMA, BRA, HEVAC and HPA. Of these, the 

British Refrigeration Association (BRA) is the trade association representing manufacturers, importers, 

wholesalers, distributors, contractors, specifiers and end-users of refrigeration plant, equipment and 

components. It also includes producers of refrigerants and lubricants, colleges and training establishments. It works closely with government, public bodies and other organisations, both in the UK and 

overseas, to further the interests of the refrigeration industry.

Green Cooling Association (GCA) (http://greencooling.org)

Green Cooling Association is an organisation for environmentally responsible refrigeration and air 

conditioning practitioners and anyone interested in promoting genuinely climate friendly refrigerant 

alternative. It is an Australian-based organisation concerned with the promotion of the transition to 

natural refrigerants in the refrigeration and air conditioning industries.

Hydrocarbons 21 (www.hydrocarbons21.com) 

Hydrocarbons21.com is an internet site that supports the worldwide use of hydrocarbons as natural and 

energy-efficient refrigerants in heating and cooling. It contains daily news, a showcase of components 

and engineering options, a global directory, papers and other features.

Natural Refrigerants Fund (NRF) (www.nrfund.org) 

NRF is an initiative to establish a natural refrigerants fund with the aim of encouraging the implementation of technologies with natural refrigerants in developing countries together with developed countries.

REFCOM (www.refcom.org.uk) 

REFCOM is a registration scheme for companies that are competent to handle refrigerants. It was set up 

in 1994 in response to atmospheric damage caused by certain refrigerant gases. Since then the Register 

has evolved to cover fluorinated refrigerant gases which if released to atmosphere have a GWP significantly higher than CO2

.
265

Refrigerants, Naturally! (www.refrigerantsnaturally.com) 

Refrigerants, Naturally! is a global initiative of companies committed to combat climate change and 

ozone layer depletion by substituting harmful fluorinated gases (“F-gases”, such as CFCs, HCFCs and 

HFCs) with natural refrigerants. Current members of Refrigerants, Naturally! include The Coca-Cola 

Company, Unilever, McDonalds, Carlsberg, and PepsiCo. In addition to the corporate members, 

Greenpeace and the United Nations Environment Programme (UNEP) both support Refrigerants, 

Naturally! and take an advising role in its management.

Refrigeration and Air Conditioning Manufacturers Association (RAMA) (www.rama.org.in) 

RAMA promotes the overall growth of the air conditioning and refrigeration industry in India. They are 

responsible for collecting and disseminating industry statistics relating to production, sales and other 

vital economic indicators to members and the Government; conducting and facilitating research about 

the AC&R industry; organising and facilitating seminars, conferences and lectures to benefit industry 

professionals; and working alongside industry associations and scientific bodies to keep RAMA members 

current on the latest standards and developments and to facilitate adoptions of standards related to 

manufacturing, energy efficiency and environment management. 

Verband Deutscher Maschinen- und Anlagenbau e.V., [German Engineering Federation] (VDMA) 

(www.vdma.org) 

The VDMA is one of the key association service providers in Europe and offers the largest engineering 

industry network in Europe. The VDMA represents 3,000 mainly small/medium size member companies in the engineering industry, making it one of the largest and most important industrial associations 

in Europe.

Institutes and associations

Chinese Association of Refrigeration (CAR) (www.car.org.cn) 

CAR is a national scientific organisation in the field of refrigeration and air conditioning industry and 

trade, which is subordinated to China Association for Science and Technology (CAST). CAR aims at 

solidifying and serving CAR members and technical personnel in the field of refrigeration. For the development of science and technology of China refrigeration, CAR has conducted many activities, such as 

facilitating domestic and international scientific communication as well as formulating and revising 

standards of the technologies and products in the field of refrigeration.

German Society of Refrigerating and Air Conditioning (DKV) (www.dkv.org) 

DKV is a unique German technical-research organisation for refrigeration, air conditioning and heat 

pump technology. The organisation was founded 1909 in Berlin and has to-date 1300 members in 

Germany as well as in foreign countries. The society’s main objectives include: advancing the arts and 

science and research of refrigeration, heating and air conditioning and promoting the international 

relationship between technicians and scientists working in the same field as well as conducting joint 

research projects.

Heat Pump Centre (HPC) (www.heatpumpcentre.org)

The HPC is an international information service for heat pumping technologies, applications and 

markets. The goal is to accelerate the implementation of heat pumps and related heat pumping technologies, including air conditioning and refrigeration. It is the central information activity of the IEA Heat 

Pump Programme (HPP). HPP operates under the International Energy Agency (IEA) and its participants in different countries cooperate in projects.
266

International Institute of Refrigeration (IIR) (www.iifiir.org/en/) 

The IIR is a scientific and technical intergovernmental organisation enabling pooling of scientific and 

industrial know-how in all refrigeration fields on a worldwide scale. The IIR’s mission is to promote 

knowledge of refrigeration technology and all its applications in order to address today’s major issues, 

including food safety and protection of the environment (reduction of global warming, prevention of 

ozone depletion), and the development of the least developed countries (food, health). The IIR commits 

itself to improving quality of life and promotes sustainable development.

International Institute of Ammonia Refrigeration (IIAR) (www.iiar.org) 

IIAR is an organisation providing advocacy, education, standards and information for the benefit of the 

ammonia refrigeration industry worldwide. IIAR’s vision is to be recognised as the world’s leading 

advocate for the safe, reliable and efficient use of ammonia and other natural refrigerants for industrial 

applications.

Institute of Refrigeration (IOR) (www.ior.org.uk) 

The IOR is an independent organisation for refrigeration and air conditioning professionals by refrigeration and air conditioning professionals. IOR’s mission is to be the forum for all those involved professionally in Refrigeration Science and Engineering; to promote the technical advancement of refrigeration 

in all its applications, in relation both to the perfection of its methods and the minimisation of its effects 

on the environment; to encourage the extension of refrigeration, air conditioning and heat pump services 

for the benefit of the community; to promote means of communication for exchange of expertise and 

interchange of views, and to communicate knowledge of refrigeration and its communal benefits to the 

outside world; and to encourage invention and research in all matters relating to the science and practice 

of refrigeration.

Laboratory of Air Conditioning and Refrigeration in Brazil (LaAR) (www.laar.unb.br) 

The LaAR aims to contribute to the scientific and technological advancement in the field of refrigeration, heating, ventilation and air conditioning. Through modern experimental techniques, modelling 

and simulation studies, the LaAR works in human resources education and research for the development 

of thermal systems more efficient and less environmental impact.

TÜV SÜD (www.tuev-sued.de/home_en) 

TÜV SÜD Group is a globally active, future-oriented company, but also continues to enjoy success in its 

traditional services such as periodic vehicle roadworthiness testing, the testing and inspection of industrial plants, product testing and expert opinions. TÜV SÜD is represented international at 600 sites and 

it employed about 13,300 people. TÜV SÜD was established 140 years ago by boiler operators as a 

private-sector regulatory body with the business objective of “protection man, then environment and 

property against the adverse effects of technology in the industrial centres of the German Länder 

Baden-Württemberg, Bavaria, Hesse and Saxony. There followed a gradual expansion of the Company’s 

scope of activities in line with technological process e.g. electrical power, motor vehicles, fire safety, 

power station, engineering, passenger lifts, ropeways, environmental protection, product safety and 

management systems. TÜV SÜD also internationalised its operations by establishing operations in other 

countries of the EU, in the USA and in the Far East. The range of services of the Centre of Competence 

for Refrigeration embraces consultancy, inspections, tests and expert opinions as well as certification and 

training. Long practical experience of our experts and the permanent cooperation in national and 

international committees complete our business activities. The CoC for Refrigeration is active on this 

sector over 30 years and obtains an own accredited laboratory. 
267

Development agencies and international funds

United Nations Environment Programme (UNEP) (www.unep.org) 

The United Nations Environment Programme (UNEP) is an advocate, educator, catalyst and facilitator, 

promoting the wise use of the planet’s natural assets for sustainable development. UNEP’s mission is to 

provide leadership and encourage partnership in caring for the environment by inspiring, informing and 

enabling nations and people to improve their quality of life without compromising that of future generations.

United Nations Development Programme (UNDP) (www.undp.org) 

UNDP is the UN’s global development network, an organisation advocating for change and connecting 

countries to knowledge, experience and resources to help people build a better life. 

United Nations Industrial Development Organisation (UNIDO) (www.unido.org) 

The United Nations Industrial Development Organisation is mandated to promote industrial development and international industrial cooperation. 

Bilateral implementing agencies 

A list of bilateral agencies can be found on the following website: 

http://www.oecd.org/linklist/0,3435,en_2649_33721_1797105_1_1_1_1,00.html 

Agence Française de Développement (AFD) (www.afd.fr/jahia/Jahia) 

Agence Française de Développement, is a French bilateral development cooperation agency, which 

supports over 60 developing countries on behalf of the French Government.

Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) (www.gtz.de/de/index.htm) 

As an international cooperation enterprise for sustainable development with worldwide operations, the 

federally owned Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH supports the 

German Government in achieving its development-policy objectives. It provides viable, forward-looking 

solutions for political, economic, ecological and social development in a globalised world. Working 

under difficult conditions, GTZ promotes complex reforms and change processes. Its corporate objective 

is to improve people’s living conditions on a sustainable basis.

Swiss Agency for Development and Cooperation (SDC) (www.sdc.admin.ch) 

The Swiss Agency for Development and Cooperation is Switzerland’s international cooperation agency 

within the Federal Department of Foreign Affairs (FDFA).

International Funds

Clean Technology Fund (CTF) (www.climateinvestmentfunds.org/cif/node/2) 

Established in July 2008, the Clean Technology Fund is one of the two (along with the Strategic Climate Fund) multi-donor Trust Funds within the World Bank’s Climate Investment Funds (CIF). It aims 

to finance transformational actions by: providing positive incentives for the demonstration of low carbon 

development and mitigation of greenhouse gas emissions through public and private sector investments; 

promoting scaled-up deployment, diffusion and transfer of clean technologies by funding low carbon 

programmes and projects that are embedded in national plans and strategies to accelerate their implementation; promoting realisation of environmental and social co-benefits thus demonstrating the 

potential for low-carbon technologies to contribute to sustainable development and the achievement of 

the Millennium Development Goals; promoting international cooperation on climate change and 

supporting agreement on the future of the climate change regime; utilising skills and capabilities of the 
268

MDBs to raise and deliver new and additional resources, including official and concessional funding, at 

significant scale; and providing experience and lessons in responding to the challenge of climate change 

through learning-by-doing. 

Global Environment Facility (GEF) (www.thegef.org/gef) 

The Global Environment Facility is an international partnership among 178 countries, international 

institutions, non-governmental organisations (NGOs), and the private sector to address global environmental issues while supporting national sustainable development initiatives. It provides grants for 

projects related to six focal areas: biodiversity, climate change, international waters, land degradation, the 

ozone layer, and persistent organic pollutants.

International Climate Initiative (ICI) (www.bmu-klimaschutzinitiative.de/en/home_i) 

The International Climate Initiative is a fund of the German Government. The overall objective of the 

fund is to provide financial support to international projects supporting climate change mitigation, 

adaptation and biodiversity projects with climate relevance. The German ICI provides financial support 

to international projects supporting climate change mitigation, adaptation and biodiversity projects with 

climate relevance. It aims to ensure that such investments will trigger private investments of a greater 

magnitude. It also aims to ensure that financed projects will strategically support the post-2012 climate 

change negotiations. For this purpose, it will support multilateral activities and funds focusing on 

adaptation and forest management.

Multilateral Fund for the Implementation of the Montreal Protocol (MLF) (www.multilateralfund.org) 

Following the London Amendment to the Protocol in 1990, a financial mechanism called the Multilateral Fund was established to provide assistance in the form of grants and concessional loans to those 

countries (Article 5 countries) with an annual per capita consumption of ODS of less than 0.3 kg a year 

which needed help to achieve the Protocol’s phase-out goals. Donations from developed countries sustain 

the Multilateral Fund and to date, pledges amount to US$ 2.55 billion over the period 1991 to 2009. 

The Fund provides finance for activities including the closure of ODS production plants and industrial 

conversion, technical assistance, information dissemination, training and capacity building aimed at 

phasing out the ODS used in a broad range of sectors.

Natural Refrigerants Fund (NRF) (www.nrfund.org) 

The NRF is an initiative for establishing a natural refrigerants fund. The aim is the implementation of 

technologies with natural refrigerants in developing countries together with developed countries.

The Environmental Transformation Fund – International window (ETF – IW) (no internet site)

The Environmental Transformation Fund – International window is an initiative of the government of 

the UK that focuses on poverty reduction, environmental protection and helping developing countries 

tackle climate change. In the course of its development, a large proportion of the proposed funding of 

the ETF-IW has been allocated to the World Bank-administered Climate Investment Funds (CIFs).

The World Bank (www.worldbank.org) 

The World Bank is a group of five international organisations providing financial and technical assistance to developing countries for the purposes of economic development and eliminating poverty.

National authorities

National Ozone Units

The National Ozone Units (NOUs) are national focal points for the implementation of the Montreal 

Protocol. NOUs are key to any decisions and actions related to the implementation of the phase-out 

plans for HCFCs in their countries. Contact details are available at UNEP’s Ozone Action Branch 

internet site: www.unep.fr/ozonaction/information/contacts.htm 
269

APPENDIX 4: FLAMMABLE CHARACTERISTICS OF HCs

Introduction

It is important to understand the characteristics of a fluid that describe its “flammability”, or the ease 

with which a substance will ignite. A variety of measures exist to evaluate this, but the main parameters 

which describe the ability of mixtures of substances in air to propagate a flame and/or explode include:

• Flash point temperature 

• Lower flammable limit

• Upper flammable limit

• Stoichiometric concentration

• Auto-ignition temperature

• Minimum ignition energy

• Heat of combustion

• Adiabatic flame temperature

• Laminar flame speed

Few of these parameters are fundamental physical or chemical properties of a substance or mixture. 

Instead, most are defined by standardised tests and, for this reason values of the parameters will change 

if the test conditions are varied. For example, values will change considerably if the concentration of 

oxygen in the mixture or of the surrounding temperature or humidity is changed. Thus, the reported 

values of a given substance may be less relevant if the conditions within which it is used differ significantly from those of the test conditions. 

Description of characteristics

A list of the flammable properties is provided in Table 24. Values for this data have been taken from a 

number of sources43. 

Flash point (°C)

This is the minimum temperature of a liquid substance that is needed to generate sufficient vapour so 

that it can be ignited. Thus, below the flash point temperature, there is insufficient vapour for a flame 

to occur. As with other characteristics, the flash point may be measured in different ways, although the 

preferred method is the “small scale closed-cup”. Substances with a flash point below +21°C are termed 

“extremely flammable”, whilst those with flash points between +21°C and +55°C are “flammable”, and 

those above +55°C are “combustible”. Common HC refrigerants are all extremely flammable.

Lower flammability limit (%, kg/m3

)

This is the lowest concentration of gas in air that is necessary for the mixture to ignite in the presence 

of a source of ignition. Below the lower flammability limit, there is insufficient fuel for burning to occur. 

A range of values normally exist for any one substance, because of its sensitivity to choice of ignition 

source, pressure, mixture temperature and air humidity.

43 Coward, HF and GW Jones, 1952, Limits of flammability of gases and vapours, Bulletin 503, Bureau of Mines; Harris, RJ, 1983, 

Gas explosions in buildings and heating plant, British Gas Corp., EF & N Spon Ltd., UK; Kuchta, JM, 1985, Investigation of fire and 

explosion accidents in the chemical, mining, and fuel-related industries – a manual, Bulletin 680, U.S. Bureau of Mines; 

Woodward, JL, 1998, Estimating the flammable mass of a vapour cloud, Centre for Chemical Process Safety, American Institute 

of Chemical Engineers, New York, USA; Zabetakis, MG, 1965, Flammability characteristics of combustible gases and vapours, 

Bulletin 627, Bureau of Mines
270

Table 24: Flammable properties of several HC refrigerants

Property R600a R290 R1270 R290/ 

R600a †

R290/ 

R170 ‡

Flash point (°C) -83 -104 -108 -94 -106

Auto-ignition 

temperature (°C)

460 470 455 465 470

Minimum ignition 

energy (mJ)

0.25 0.25 0.28 0.25 0.25

Lower Flammability (kg/m3

)

Limit 

 (%)

0.043 0.038 0.043 0.040 0.038

1.80 2.10 2.50 1.95 2.15

Upper Flammability (kg/m3

) 

Limit 

 (%)

0.202 0.171 0.174 0.186 0.172

8.5 9.5 10.1 9.0 9.7

Stoichiometric (kg/m3) 

concentration

 (%)

0.074 0.072 0.077 0.073 0.073

3.1 4.0 4.4 3.5 4.1

Heat of combustion (kJ/kg) 49500 50500 49000 50000 50600

Adiabatic flame temperature 

(°C)

2010 1970 2050 1990 1960

Laminar flame speed (m/s) 0.37 0.43 0.48 0.40 0.43

† Based on 50% R290 and 50% R600a molar composition

‡ Based on 94% R290 and 6% R170 molar composition
271

Upper flammability limit (%, kg/m3)

This is the highest concentration of gas in air that allows for the mixture to ignite in the presence of a 

source of ignition. Above the upper flammability limit, there is insufficient oxygen for burning to occur. 

A range of values normally exist for any one substance, because of its sensitivity to choice of ignition 

source, pressure, mixture temperature and air humidity.

Stoichiometric concentration (%, kg/m3

)

This is the concentration of a fuel in air where complete conversion, or oxidation, of all the fuel and 

consumption of all oxygen occurs. Thus, after burning of an HC in air, only carbon dioxide and water 

remain. Typically, the stoichiometric concentration is when the mixture is most reactive and therefore 

the "most flammable" concentration.

Auto-ignition temperature (°C)

This is the minimum temperature of a surface that can ignite the gas. Specifically it is defined as the 

lowest temperature to which a given mixture of a fuel and air must be heated to combust spontaneously 

in the absence of any other ignition source. It is determined as the lowest temperature of a glass surface 

(since it is assumed to be chemically inert) at which droplets of a liquid falling onto the surface will 

undergo spontaneous combustion. Because of catalytic effects, the values for other types of surfaces can 

be lower. There is also a time delay involved in auto-ignition temperature of the mixture, where a higher 

surface temperature will result in a faster occurrence of ignition. The auto-ignition temperature is also 

rather sensitive to air temperature, humidity and space dimensions. It also varies depending upon the 

concentration as indicated by Figure 73.

Figure 73: Variation of auto-ignition temperature with gas concentration

Minimum ignition energy (mJ)

This is the minimum energy that can ignite a mixture of a flammable substance and air, normally close 

to the stoichiometric concentration. Typically, the energy is generated by an electrostatic spark discharge 

released from a capacitive electrical circuit. Different test methods employ different circuit components 

and the arrangement of electrodes, resulting in a variation in values. There is a very wide variation of 

minimum ignition energy depending upon the mixture concentration, as illustrated in Figure 74. For 

example, the minimum ignition energy required to ignite a mixture close to the lower or upper flammability limits is several thousand times greater than at the stoichiometric concentration. 

e it the concentration that it is most reactive. This concentration can be calculated 

perature (°C) 

um temperature of a surface that can ignite the gas. Specifically it is defined as 

rature to which a given mixture of a fuel and air must be heated to combust 

 the absence of any other ignition source. It is determined as the lowest 

glass surface (since it is assumed to be chemically inert) at which droplets of a 

the surface will undergo spontaneous combustion. Because of catalytic effects, 

er types of surfaces can be lower. There is also a time delay involved in auto

ure of the mixture, where a higher surface temperature will result in a faster 

ition. The auto-ignition temperature is also rather sensitive to air temperature, 

ce dimensions. It also varies depending upon the concentration as indicated by 

ure 73: Variation of auto-ignition temperature with gas concentration 

 energy (mJ) 

um energy that can ignite a mixture of a flammable substance and air, normally 

hiometric concentration. Typically, the energy is generated by an electrostatic 

eleased from a capacitive electrical circuit. Different test methods employ 

omponents and the arrangement of electrodes, resulting in a variation in values. 

de variation of minimum ignition energy depending upon the mixture 

 illustrated in Figure 74. For example, the minimum ignition energy required to 

ose to the lower or upper flammability limits is several thousand times greater 

ometric concentration. 
272

Figure 74: Variation of minimum ignition energy with gas concentration

Heat of combustion (kJ/kg)

The heat of combustion – or energy of combustion, heating value, calorific value, etc – is the amount of 

heat energy given off from complete burning of the fuel and air mixture (i.e., at stoichiometric concentration). At other concentrations, the heat of combustion is lower, as shown in Figure 75. The value can 

be obtained from enthalpy balance of burned and unburned mixture, and it is also determined through 

measurement. When considering the heat of combustion for fuel purposes, a number of variations are 

used depending upon what the final temperature of the burned mixture is, and whether the water vapour 

has condensed back to liquid. 

Figure 75: Variation of heat of combustion with gas concentration

Adiabatic flame temperature (°C)

This is the maximum temperature of the flame of the burned fuel-air mixture, close to the stoichiometric concentration and assuming no heat loss to the environment. For a given set of conditions, the 

adiabatic flame temperature can be calculated (though enthalpy balance of burned and unburned 

mixture), although measured values tend to be about 100 K lower than this. Values listed in Table 1 are 

the calculated ones. Since the heat of combustion varies with concentration, so does the flame temperature slightly, as indicated in Figure 76.

333

Figure 74: Variation of minimum ignition energy with gas concentration 

mbustion (kJ/kg) 

of combustion – or energy of combustion, heating value, calorific value, etc – is the 

heat energy given off from complete burning of the fuel and air mixture (i.e., at 

etric concentration). At other concentrations, the heat of combustion is lower, as shown in 

 The value can be obtained from enthalpy balance of burned and unburned mixture, and 

etermined through measurement. When considering the heat of combustion for fuel 

a number of variations are used depending upon what the final temperature of the 

xture is, and whether the water vapour has condensed back to liquid. 

Figure 75: Variation of heat of combustion with gas concentration 

flame temperature (°C) 

 maximum temperature of the flame of the burned fuel-air mixture, close to the 

etric concentration and assuming no heat loss to the environment. For a given set of 

 the adiabatic flame temperature can be calculated (though enthalpy balance of burned 

ned mixture), although measured values tend to be about 100 K lower than this. Values 

able 1 are the calculated ones. Since the heat of combustion varies with concentration, 

e flame temperature slightly, as indicated in Figure 76. 

333

Figure 74: Variation of minimum ignition energy with gas concentration 

mbustion (kJ/kg) 

of combustion – or energy of combustion, heating value, calorific value, etc – is the 

heat energy given off from complete burning of the fuel and air mixture (i.e., at 

etric concentration). At other concentrations, the heat of combustion is lower, as shown in 

 The value can be obtained from enthalpy balance of burned and unburned mixture, and 

etermined through measurement. When considering the heat of combustion for fuel 

a number of variations are used depending upon what the final temperature of the 

xture is, and whether the water vapour has condensed back to liquid. 

Figure 75: Variation of heat of combustion with gas concentration 

flame temperature (°C) 

 maximum temperature of the flame of the burned fuel-air mixture, close to the 

etric concentration and assuming no heat loss to the environment. For a given set of 

 the adiabatic flame temperature can be calculated (though enthalpy balance of burned 

ned mixture), although measured values tend to be about 100 K lower than this. Values 

able 1 are the calculated ones. Since the heat of combustion varies with concentration, 

e flame temperature slightly, as indicated in Figure 76. 
273

Figure 76: Variation of adiabatic flame temperature with gas concentration

Laminar flame speed (m/s)

Laminar flame speed – or laminar burning velocity – is a representation of the rate of expansion of the 

flame front as the mixture burns. The value is normally obtained through measurement, and is also 

highly sensitive to many factors, such as concentration (Figure 77). It provides an indication of how 

rapidly the fuel-air mixture burns under ideal, steady conditions. By comparison, turbulent flame speeds 

occur under non-uniform conditions, and can be several magnitudes higher.

Figure 77: Variation of laminar flame speed with gas concentration

334

ure 76: Variation of adiabatic flame temperature with gas concentration 

peed (m/s) 

peed – or laminar burning velocity – is a representation of the rate of expansion of 

s the mixture burns. The value is normally obtained through measurement, and is 

tive to many factors, such as concentration (Figure 77). It provides an indication of 

uel-air mixture burns under ideal, steady conditions. By comparison, turbulent 

cur under non-uniform conditions, and can be several magnitudes higher. 

Figure 77: Variation of laminar flame speed with gas concentration 

334

re 76: Variation of adiabatic flame temperature with gas concentration 

peed (m/s) 

peed – or laminar burning velocity – is a representation of the rate of expansion of 

s the mixture burns. The value is normally obtained through measurement, and is 

tive to many factors, such as concentration (Figure 77). It provides an indication of 

uel-air mixture burns under ideal, steady conditions. By comparison, turbulent 

cur under non-uniform conditions, and can be several magnitudes higher. 

Figure 77: Variation of laminar flame speed with gas concentration 
274

APPENDIX 5: CALCULATION OF CONCENTRATIONS FROM A RELEASE

Introduction44 

Sometimes it may be useful to try to estimate the likely concentrations arising from a release of refrigerant into a space. In general, the concentration development is rather variable and sensitive to a number of 

different parameters. However, a correlation is presented here in order to assist with carrying out such 

evaluations, which is based on a number of experiments and results from several different studies. 

The calculation is based around two separate release scenarios:

• Determination of the maximum mean floor concentration (C

_

f,max, in kg/m3

) – which is an averaged 

value of all floor-level sampling points at each time increment, of which the highest value is taken –

resulting from a “catastrophic” release

• Determination C

_

f,max for a prolonged release

Depending upon the combination of conditions, the concentration may vary extensively at a single 

point on the room floor, and the concentration at the same time will also differ widely amongst different 

positions across the floor. For this reason, the correlation is based around an average value for the floor 

at any given time (based on area-weighted concentration measurements at different locations across 

the room floor), C

_

f

 , and the maximum of these averaged values, C

_

f,max, is used as the concentration 

of interest. Given the high variations in local concentrations, the used of C

_

f

 and C

_

f,max have been shown 

to be the most robust indicators of the refrigerant dispersion. Figure 1 attempts to illustrate this concept, 

where the faint lines indicate local concentrations and the red line is C

_

f , eventually peaking at C

_

f,max.

Figure 78: Example of differing floor concentrations and averaged values

Calculation for catastrophic release45

A “catastrophic” release is considered to represent the most hazardous situation in terms of producing a 

high concentration, and in this case, is taken to be a release of the entire refrigerant charge over a period 

of 210 s, assuming a constant mass flow rate. 

The C

_

f

 following a release is a function of various characteristics associated with the design and installation of that equipment. The independent variables – those that can be specified within the design and 

construction of the equipment – are: 

335

er of different parameters. However, a correlation is presented here in order to assist 

ng out such evaluations, which is based on a number of experiments and results from 

ferent studies. 

ation is based around two separate release scenarios: 

mination of the maximum mean floor concentration (Cf,max , in kg/m3) – which is an 

ed value of all floor-level sampling points at each time increment, of which the highest 

s taken –resulting from a “catastrophic” release 

mination Cf,max for a prolonged release 

g upon the combination of conditions, the concentration may vary extensively at a single 

e room floor, and the concentration at the same time will also differ widely amongst 

ositions across the floor. For this reason, the correlation is based around an average 

he floor at any given time (based on area-weighted concentration measurements at 

cations across the room floor), Cf , and the maximum of these averaged values, Cf,max , is 

e concentration of interest. Given the high variations in local concentrations, the used of 

max have been shown to be the most robust indicators of the refrigerant dispersion. 

ttempts to illustrate this concept, where the faint lines indicate local concentrations and 

e is Cf , eventually peaking at Cf,max . 

Figure 1: Example of differing floor concentrations and averaged values 

ourne and Suen (2008); Colbourne and Suen (2003) 

44 See Colbourne and Suen (2008); Colbourne and Suen (2003)

45 In reality, the mass flow of a real catastrophic leak is not constant; it tends to rise rapidly to a maximum value, and then 

depending upon the orifice size, after some period exhibits decay as the internal pressure falls and the remaining refrigerant 

desorbs from the compressor oil. Further, the time taken for some percentage of the refrigerant to exit the system is dependent 

upon the location and size of the orifice, whether the system is on or off, length and size of pipes and the presence and status of 

in-line controls such as solenoid valves, and so on.
275

• Refrigerant mass released, mr (kg)

• Room air movement, such as airflow from a fan, Vd (m3

/s)

• Height that the air is discharged from, hd (m)

• Direction if that air discharge, Θ(rad)

• Height of the release, hr (m), such as the lowest of any refrigerant-containing parts

• Refrigerant density, ρr (kg/m3

)

• Room size, VRm (m3

) or room area, ARm (m2) 

Some of these parameters are indicated in Figure 79.

Figure 79: Schematic diagram of parameters involved in estimation of concentration

C

_

f,max is obtained from the product of the mixing effectiveness, ε , and C

_

Rm (equation 23), where ε is 

then established as a function of Richardson number, Ri , and the ratio hd / hr (equation 24).

C

_

f,max = εC

_

Rm , ε ≥ 1 (23)

 ε ≥ 1 (24)

 

The mean maximum concentration always occurs at floor level so C

_

f,max cannot be lower than the 

homogenous concentration; therefore equations. (23) and (24) are only valid when ε ≥ 1. There are 

several numerical definitions of Ri in use, and in the present case the conventional equation definition of 

is employed (equation 25), but with the inclusion of a discharge angle adjustment factor (ξ).

 (25)

where u

_

Rm,min (m/s) is the minimum room air speed (as discussed below), and the reduced gravity (g ́) 

represents the buoyancy of the refrigerant relative to the air (equation 26). 

 

 (26)

where g is gravitational acceleration, ρr (kg/m3

) is density of the released gas (at room temperature), and 

ρa (kg/m3) is the density of air (based on room temperature and atmospheric pressure).

336

ass released, mr (kg) 

ement, such as airflow from a fan, Vd

& (m3

/s) 

e air is discharged from, hd (m) 

at air discharge, θ (rad) 

elease, hr (m), such as the lowest of any refrigerant-containing parts 

nsity, ρr (kg/m3) 

m (m3

) or room area, ARm (m2) 

rameters are indicated in Figure 2. 

Schematic diagram of parameters involved in estimation of concentration 

from the product of the mixing effectiveness, ε , and CRm (equation 23), where ε

d as a function of Richardson number, Ri , and the ratio hd / hr (equation 24). 

ss flow of a real catastrophic leak is not constant; it tends to rise rapidly to a maximum 

pending upon the orifice size, after some period exhibits decay as the internal pressure 

ing refrigerant desorbs from the compressor oil. Further, the time taken for some 

efrigerant to exit the system is dependent upon the location and size of the orifice, 

 is on or off, length and size of pipes and the presence and status of in-line controls such 

and so on. 
276

Since entrainment of a release into the air is normally a function of velocity, air volume flow rate from 

the unit and duct discharge area, Ad (m2

) are combined to obtain the mean room air speed, u

_

Rm,min 

(m/s). Equation 27 is used for calculating u

_

Rm,min, whilst employing a discharge coefficient, cd = 0.45.

 (27)

The adjustment factor (ξ) is introduced and applied to u

_

Rm to account for the effect of non-horizontal 

air discharge (equation 28). It includes the relative height of air discharge to room height since it is 

expected that the influence of discharge angle on mixing is less apparent as the height of air discharge 

approaches floor level. 

 

ξ = exp [ (hd / hRm)(-1.21Θ+1.46) (28)

The angle of the discharge, Θ (in radians) is defined relative to the vertical plane. For example, Θ = 90° 

= ∏ rad for a horizontal discharge and Θ = 60° = ∏ rad for a jet sloping downward.

Lastly, where there is little or no forced air movement present (u

_

Rm ≈ 0) equation (23) and (24) give 

unrealistically high values of . This is because the air speed in a quiescent room is not actually “still” 

and typically in the range 0.03 – 0.05 m/s (regardless of the duration that it is left undisturbed). In order 

to address this situation, a formula for determining a minimum air speed was obtained. Thus, when 

there is a very low airspeed, the terms u

_

Rm ξ in equation (25) becomes u

_

Rm,min from equation (29).

 (29)

 

Calculation for non-catastrophic releases

Whilst evaluation of C

_

f,max may be important for predicting the worse case concentrations, it is also 

useful to predict the concentrations resulting from slower releases. This is particularly relevant when 

considering the case of a release continuing after forced airflow has ceased. Therefore, an additional set 

of formulae is used for releases lasting more than 210 s. This uses a characterisation of the concentration 

development over time, and the extrapolation of the concentration change of a catastrophic release over 

an extended duration, as illustrated in Figure 80.

Figure 80: Gradient of floor concentration development with time

Although at the start of a release (typically for the first 50 – 100 s) the concentration-time profile tends 

to be erratic, a correlation can be observed between 1/C

_

f

 and time following the initiation of the release. 

Lastly, where there is little or no forced air movement present (uRm ≈ 0) equation (23) and (24) give 

unrealistically high values of Cf,max . This is because the air speed in a quiescent room is not 

actually “still” and typically in the range 0.03 – 0.05 m/s (regardless of the duration that it is left 

undisturbed). In order to address this situation, a formula for determining a minimum air speed was 

obtained. Thus, when there is a very low airspeed, the terms uRm ξ in equation (25) becomes 

uRm,min from equation (29). 

3/2

r

Rm,min

Rm Rm

0.1 h g u =

h A

′ , uRm,min ≤ uRm ξ (29) 

Calculation for non-catastrophic releases 

Whilst evaluation of Cf,max may be important for predicting the worse case concentrations, it is also 

useful to predict the concentrations resulting from slower releases. This is particularly relevant 

when considering the case of a release continuing after forced airflow has ceased. Therefore, an 

additional set of formulae is used for releases lasting more than 210 s. This uses a characterisation 

of the concentration development over time, and the extrapolation of the concentration change of a 

catastrophic release over an extended duration, as illustrated in Figure 3. 

Although at the start of a release (typically for the first 50 – 100 s) the concentration-time profile 

tends to be erratic, a correlation can be observed between 1/ Cf and time following the initiation of 

the release. Therefore, if Cf

max for a catastrophic release is calculated (as above), then the 

Figure 3: Gradient of floor concentration development with time 
277

Therefore, if C

_

f,max for a catastrophic release is calculated (as above), then the increase in concentration 

as the release continues past 210 s can then be estimated. By setting the first increment C

_

f = C

_

f,max,210

and tr = tr,210 for a catastrophic release, equation (30) can be used to estimate C

_

f

 at any tr > 210 s.

 (30)

Based on the mass that is released after 210 s, C

_

f,max,210 is calculated from equations (23) and (24), 

but using C

_

Rm,max,210 (i.e., C

_

Rm had the release stopped at 210 s) instead of C

_

Rm (tr

), as obtained from 

equation (31).

 (31)

The index in equation (30) indicates the shape of the curve of the concentration development over time 

(following the first 50 – 100 s). Where the mixing is very effective (i.e., ε ≈ 1), the gradient dC

_

f /dt is 

almost linear, implying that n ≈ 1, whereas where the mixing is poor (a low ε) the gradient dC

_

f

 changes, 

and therefore n < 1. Subsequently the relation between n and ε in equation (32) can be used.

 

n = 1/ ε (32)

Final remarks

As mentioned earlier, the local environmental conditions, room geometry, release characteristics and 

many other factors can affect the concentration of a refrigerant release within a space. These correlations 

help to provide an indication of the average concentrations that may arise within the room. Of course 

when a leak occurs from a system, the refrigerant will initially be at a concentration of 100%, and there 

will be localised concentrations at very high values at some positions within the space, irrespective of the 

quantity release or the other conditions. 

These correlations were based on a number of experiments and compared against a large number of data 

from other studies. Across these comparisons, it was found that the calculated C

_

f,max were within ± 50% 

of measurements for over 80% of the cases. In addition, on average the calculated values of C

_

f,max were 

16% higher than the measurement. By comparison with other models and correlations used for estimating concentrations arising from gas releases (for example, in other industries), this is considered to be a 

fairly accurate result. Of course it is important to consider the range of parameters under which these 

correlations were developed and to bear in mind that using them for situations outside these limits may 

lead to greater errors. In general, the limits are approximately:

• Refrigerant mass between 0.1 kg to 2.5 kg

• Room size from 5 m2

 to 50 m2

• Air speed from 0.02 m/s to 0.4 m/s

• Refrigerant release height from 0.2 m to 3 m

Lastly, it should be noted that most of the measurements were carried out under conditions that would 

otherwise promote poor missing within the room, thereby aiming for as high a concentration as possible. 

These include very low release velocities, in vapour phase in a downward release direction, and using 

rooms that are well sealed to avoid any thermal or infiltration air currents. Therefore it is expected that 

these calculations will return the higher attainable concentrations for a given set of conditions. 
278

APPENDIX 6: EQUIPMENT FOR TECHNICIAN TRAINING

List of tools and equipment

Qt. Description Minimum 

required

Ideal

1 20 Tool box (metal) ✔

2 20 Pair of safety gloves refrigerant handling (acid-resistant) ✔

3 20 Pair of safety gloves for mechanical work ✔

4 20 Safety goggles ✔

5 20 Folding rules 2 m ✔

6 20 Steel ruler (40 cm) ✔

7 20 Spirit level ✔

8 20 Quick square ✔

9 20 Digital calliper ✔

10 20 Flash light ✔

11 20 Centre punch ✔

12 20 Cable knife ✔

13 20 Cable reel about 10 m ✔

14 20 Hacksaw and extra blades (wide ca. 30 cm) ✔

15 20 Hammer 300 gram ✔

16 20 Sets of files (round, flat, triangle) ✔ 

17 20 Scratch awl ✔

18 20 Hex key set ✔

19 20 Combination wrenches (9 pieces) set ✔

20 20 Adjustable wrenches (set of 3 different sizes) ✔

21 20 Pipe wrench (35 cm) ✔

22 20 Ratchet wrench (rota-lock) ✔
279

Qt. Description Minimum 

required

Ideal

23 20 Socket wrench and bit set ✔

24 20 Vice grip pliers ✔

25 20 Pinch-off pliers ✔

26 20 Piercing pliers 6 to 22 mm (with spare gaskets and needle) ✔

27 20 Swaging tool set ✔

28 10 Tube expander set (10 – 22 mm) ✔

29 20 Tube bender lever type or hydraulic set (10, 12, 16, 18, 22) ✔

30 20 Tube cutter, midget and large ✔

31 20 Flaring tool set ✔

32 20 Inspection mirror ✔

33 20 Set of inner/outer tube reamer & one pen type reamer ✔

34 20 Capillary tube cutter ✔

35 10 Capillary tube gauge ✔

36 20 Steel brush ✔

37 10 Set of two process tube quick connector (for 6 mm / 1⁄4”) ✔

38 10 Brazing kit (propane/oxygen) if brazing installation according 

table (1)-2 not available 

✔

39 20 Brazing heat shield (silicate fibre) ✔

40 5 Nitrogen (N2) cylinder, 20 Litre, test pressure 300 bar, working 

pressure 200 bar, mounted and secured on trolley 

✔

41 5 Pressure regulator (N2) complete with transfer hose, entr. 

Pressure 200 bar, working pressure 40 bar. 

✔

42 20 Set of screw driver (7 pieces) incl. straight, cross and Philips. 

Isolated 1000 Volt tested (EN60900)

✔

43 20 Set of 4 pliers (Electro) isolated 1000 Volt tested (EN60900) ✔

44 20 Wire stripper, isolated 1000 Volt tested (EN60900) ✔
280

Qt. Description Minimum 

required

Ideal

45 20 Pocket screw drivers set ✔

46 20 Cable ripper ✔

47 20 Socket, cable shoe, adapter set including iso. tape ✔

48 20 Clamp on ampere-meter, current, voltage, resistance, ✔

49 20 Mains tester with LED ✔

50 10 Capacitor tester ✔

51 2 Test cord, compressor starting and testing device (hermetic 

compressors)

✔

52 20 Solenoid valve operating magnet ✔

53 20 Wire crimping tool, isolated 1000 Volt tested (EN60900) ✔

54 20 Driller cordless, including set of bits and drill drivers ✔

55 20 Valve core removal tool ✔

56 20 4-valve manifold gauge set with refrigerant hoses (ball valves) 

3x1⁄4” SAE and 1x3⁄8” SAE & 3⁄8” vacuum hose

✔

57 10 Set of two extra refrigerant hoses 150 cm with ball valve, spare 

gaskets and depressors

✔

58 20 Liquid charging adapter ✔

59 10 Flare caps 1⁄4” SAE (set of 10 pieces) ✔

60 10 Electronic vacuum gauge (micron, Pa, mbar) 20 bar overpressure 

protection

✔

61 2 Compressor tester (compression checking) ✔

62 20 Pocket thermometer ✔

63 10 Precise electronic thermometer with two probes connection 

(-50 °C to 50°C) 

✔

64 10 Temperature and humidity logger with PC interface and software ✔

65 10 Electronic leak detector with visible and audible alarm, 

sensitivity 3 gram/year for halogenated refrigerants

✔
281

Qt. Description Minimum 

required

Ideal

66 10 Electronic leak detector with visible and audible alarm, 

sensitivity less than 50 ppm for HC refrigerants

✔

67 2 Reference leak for leak detectors, rate of leak 5 gram/year ✔

68 20 Leak detection fluid sprayer with solution for -6 °C to 120 °C 

surface detection temperature

✔

69 2 Sound meter ✔

70 2 Air velocity meter with extension handle air lock ✔

71 10 Electronic charging scales 50 kg, resolution 2 gram, accuracy 

+/- 0,5)%, battery powered 

✔

72 5 Charging cylinder, gram graduation, safety valve, fluctuation 

compensation, pressure/temperature indication, 

✔

73 5 Refrigerant recovery cylinder heating belt, about 400 Watt, 230 

Volt, 60 °C

✔

74 2 Refrigerant – Oil “Total Test” kit ✔

75 10 Can valve, 1⁄4” SAE connection
282

List of consumables

Qt. Description Minimum 

required

Ideal

76 Copper tubes 6 to 22 mm, brazing rods (4 % silver and 

phosphorus) and flux, flare nuts, adapters, filter-drier, etc

✔

77 HC refrigerant R-290 in about 30 pound (14 kg) cylinder, 

99,5 % purity

✔

78 HC refrigerant R-600a can, approx 400 gram, 99,5 % purity ✔

79 HC blend 50 % R600a / 50% R-290 can, approx 400 gram, 

99,5 % purity 

✔

80 Connection wires (multi-wire) different make ✔

81 Isolated cable box, 140 x 140 x 80 mm, IP 65 (IP 54) ✔

82 Capillary thermostat, domestic fridges and freezers, sealed 

design, different ranges

✔

83 Plug-in compressor start relays, solid state (sealed), 

1/12 to 1⁄2 HP 

✔

84 If available so-called sealed retrofit kits, domestic appliances, 

incl. (80-82) materials and refrigerator lighting 

✔

85 Compressor lubricant (mineral) ✔

86 Several hermetic refrigeration appliances ✔

87 Several hermetic compressors (used but functional) ✔

88 Several semi-hermetic compressors (used but functional) ✔
283

Other recommended equipment

Qt. Description Minimum 

required

Ideal

1 10 Vacuum pump, two stage, about 150 Liter/min, 15 Micron rating, 

gas-ballast valve, 1⁄4” and 3⁄8” SAE connections

v

2 10 Refrigerant recovery unit, transportable, oil-less, 1⁄2 HP, complete 

with hoses and inline filter 

✔

3 10 Portable HC charging station, vacuum pump about 35 Liter/min, 

charging scales (0 – 2000 gram) 1 gram accuracy, refrigerant 

cylinder can support with valve, vacuum gauge, one LP gauge 

R-134a, R-12, R-22, one LP gauge R-600a, all necessary charging 

hoses with ball-valve, one venting hose length 10 m and OD min. 

15 mm with vacuum pump exhaust port adapter, 

✔

4 2 Refrigerant recovery, recycling, evacuation and charging unit 

(MAC) with SAE J2788 certification, internal 30 lb recovery 

cylinder on electronic scale, non-condensable gas indication 

gauge and manual purging device, semi-automatic operation, HP 

and LP gauges for pressure/temperature indication 

✔

5 15 Refrigerant recovery cylinder 30 lb (14 kg) with two valve access. 

DOT or ADR P200 approval, 

✔

6 1 Refrigerant analyzer, portable, battery powered, with printer, 

CFCs, HCFC, HFC incl. popular blends (R-404A, R-407C, R-507A, 

R-410) and hydrocarbon

✔

7 1 Refrigerant identifier, HCFC R-22 only ✔

8 10 Refrigerators / freezers about 160 litre, different make ✔

9 2 Bottle coolers about 110 litre ✔

10 2 Refrigerated water dispenser ✔

11 2 Split air conditioning units (HCFC R-22) about 10000 BTU/h (3 kW) ✔

12 2 Condensing unit with hermetic compressor ✔

13 1 Visible cooler about 500 litre ✔

14 1 Car AC compressor, reciprocating, vane, rotary, axial (1 no. each) ✔

15 1 No-Frost upright freezer 250 litre approx ✔
284

Descriptions of tools and equipment

Picture Technical Specification

Set of four (4) insulated pliers: Universal pliers length 180 

mm, long nose pliers 160 mm, cutting pliers 180 mm, wire 

stripper 160 mm. Jaw Length about 50 mm, Chrome 

Vanadium steel, GS VDE – EN 60900 Standards, insulated 

and tested for 1000 Volts AC 

Two pin voltage tester (mains tester), display optic, LEDs, 

metering capacity – 400 V AC/DC, 1.000 V AC, IP54

7 Piece screwdriver set, ergonomic soft finish, insulated; 

slotted 2.5 x 75 mm / 4 x 100 mm / 5.5 x 125 mm; 

phillips PH1 and PH2; cross-head PZ1 and PZ2; chrome 

vanadium steel; GS VDE – EN 60900, insulated and tested 

for 1000 Volts AC 

Clamp-on ammeter, digital, 400 A - AC, voltage 600 AC, 

voltage 600 DC, resistance 20 MOhm, capacity tester 0-50 

μF, LCD, +/-1.8% + 0.6 A AC current accuracy, includes test 

leads, carrying case, battery and instructions

Set of three (3) adjustable wrenches: size 200 mm (8"), 

size 250 mm (10") 250 mm, size 300 mm (12"). chrome 

vanadium steel, chrome finish

Locking pliers (vice grip) 5 mm to 16 mm, with guarded 

release trigger and adjusting screw. Heat treated alloy 

steel with nickel-plated finish for maximum durability.e

Locking "piercing" pliers; adjustable 1/4"- 6 mm, with two 

spare piercing pins and two spare gaskets. Heat treated 

alloy steel with nickel-plated finish for maximum durability.
285

Descriptions of tools and equipment

Picture Technical Specification

Locking "pinch-off" pliers, adjustable from 6 mm to 12mm. 

Heat treated alloy steel with nickel-plated finish for 

maximum durability.

Capillary tube cutter for all capillary diameter

Set of seven (7) allen keys; sizes 2,5 / 3 / 4 / 5 / 6 / 8 

and 10, chrome vanadium steel

Ratchet wrench square: 1/4" x 3/8" and 3/16" x 5/16", 

vanadium steel construction 

Line piercing valve for copper tubes of diameter 6 up to 10 

mm. For refrigerant transfer hose connection 1/4" SAE

Set of two (2) tube cutters, tube OD 3 to 16 mm and 7 to 

41 mm, Large tube cutter with reamer and spare wheel

Flac18 mm, complete with rugged carrying case 

Expander tool set complete with expander-pliers and 

seven (7) heads in steel box to cover sizes of 10, 12, 15, 

16, 18, 22, 28 mm

Cross-bow-type tube bender set with seven different 

heads, for annealed copper tubes, with special reverse 

direction bending function. Complete set in plastic box for 

tube sizes up to 22 mm diameter. 
286

Descriptions of tools and equipment

Picture Technical Specification

Triple header tube bender (metric) for tubes OD 6 mm, 8 

mm, 10 mm to 90° bends. 

Core removal tool, core removal without refrigerant 

losses, brass with magnetic tip, one 1/4" male flare SAE 

connection and one female 1/4" connection, equipped with 

ball-valve 

Set of two (2) process tube quick-connector tools complete and ready for use on 6 mm (1/4") diameter tubes, 

consisting of tube adapter with gaskets and insert, quickcoupler (hansen) male and female, hose adapter 1/4" flare 

union.

Straight refrigerant hose / system quick connector / 

coupler

Elbow refrigerant hose / system quick connector / coupler

Extraction valve for extracting of refrigerants out of 

disposable refrigerant cans (420 g.)

Digital-precision quick response thermometer for thermocouples and simultaneous connection of two (2) plug-in 

probes. Display in two, 4 digit LCD. Probe connection in 

two jacks for flat-pin plugs. Temperature drift 0.01 %/K. 

Accuracy +/- 1 digit (at nominal temperature 25°C. Two (2) 

K-type probes for measuring range -199°C to +999°C 

according EN 60584. Push buttons as membrane keys. 

Power supply 9V battery.
287

Descriptions of tools and equipment

Picture Technical Specification

Electronic leak detector for HC refrigerants with flexible 

probe length of min 30 cm and with audible and visual 

alarms. Sensitivity less than 50 ppm of Propane, Isobutane 

and Methane. Response time 5 seconds. Operating temperature: 0°C to 50°C supplied with spare tips and rugged 

carrying case.

Electronic leak detector with flexible probe length of 

min 30 cm and with audible and visual alarms. Variable 

sensitivity, refrigerants CFC, HFC, HCFC and blends, 

indication of leaks 3 g/yr (1/10oz), visible and audible 

leak indication, complete set with spare tips and rugged 

carrying case. 

Electronic weighting scale designed for charging and 

recovery. Capacity 50 kg, Resolution 5 g, Accuracy 0.5% of 

reading, measuring units in kg and lb. Zero function, 

Battery power and low-battery indication. Rugged portable 

case. CE certification.

Electronic charging scale for HC refrigerants. Measuring 

range 0-2000 g, accuracy 1 g, battery powered, digital 

readings. Equipped with refrigerant disposal can support.

Brazing unit complete: consisting of one 2 litre oxygen and 

one 0.425 kg propane (LPG) gas cylinder. Complete set 

including valves, safety valves, pressure gauges, constant 

pressure regulator, 3m hoses, torch and tips sizes 2 and 

3 according EN 962 complete with carrying frame.

Sets of 4-valve manifold pressure gauges (3x1/4” 

and 1x3/8” connections) pulse-free, bar measurement 

indication, gauges 68 mm with refrigerant scale for 

HC R600a, and one vacuum gauge 0-1000 mbar and 

pointer and safety valve
288

Descriptions of tools and equipment

Picture Technical Specification

Sets of 2-valve manifold pressure gauges (3x1/4” and 

1x3/8” connections) pulse-free, bar measurement indication, gauges 80 mm with refrigerant scale for R22, R134a, 

R404A, R407C, including 3 refrigerant transfer hoses 90 

cm (red, blue, yellow) with ball valves and 1x3/8” standard hose (vacuum pump) 2x3/8 female straight swivel 

ends; incl. carrying case. Gauges for HC refrigerants R-290 

and R-600a available.

Sets of 5-valve manifold pressure gauges (3x1/4” 

and 1x3/8” connections) pulse-free, bar measurement 

indication, gauges 80 mm with refrigerant scale for R22, 

R134a, R404A, R407C, one vacuum gauge 0-1000 mbar 

and pointer and safety valve, including 3 refrigerant 

transfer hoses 90 cm (red, blue, yellow) with ball valves 

and 1 x 3/8” standard hose (vacuum pump) 2 x 3/8 

female straight swivel ends; incl. carrying case

Refrigerant hoses with end-mounted ball-valves. Hoses 

colour marked red, blue and yellow. Hose connection in 

1/4" SAE. Working pressure about 60 bar (870 PSI). Hose 

available in length of 90 cm (36"), 150 cm (60") and 180 

cm (72"). (Ball valve side with core-depressor)

Large 3/8" diameter heavy-duty vacuum pump connection 

hose. Shortest possible hose length for vacuum pump and 

manifold gauge connection to choose. 

Digital vacuum gauge, resolution 1 micron. Reads vacuum 

in 7 units: Micron, PSI, InHg, mbar, Pascal, Torr, mTorr. 

Cleaning port for cleaning of sensor. Accuracy ± 10 Micron 

from 100-1000 Micron. Overpressure protected up to 20 

bar.
289

Descriptions of tools and equipment

Picture Technical Specification

Two stage rotary vacuum pumps with vacuum gauge, ø 80 

mm with adjustable pointer, solenoid valve to prevent air 

from flushing back when turned off; Swept volume minimum 70 litre/min (2.5 cfm); end-vacuum: 15 micron; Oil 

level indicator with easy oil change capabilities; Normal 

and efficient operation in high ambient temperatures and 

high humidity conditions and to start under vacuum of 5 

mbar, 230-1-50/60 power requirement; Hose connection 1/4" 

and 3/8" NPT. Including 2 litre of spare vacuum pump oil.

Portable charging station for R-600a and HC blends; 

vacuum pump, double stage, minimum 35 litre/min (1.25 

cfm) displacement, factory micron rating – 15 micron; 

electronic charging scale range 0 to 2000 g and 1 g 

accuracy; vacuum gauge 80 mm diameter with pointer; 

compound gauge, Ø 68 mm, –1 to +3 bar

pressure with temperature scale for R-600a; compound 

gauge, Ø 68 mm, –1 to +10 bar pressure with temperature 

scale for R134a and R12 refrigerant; device for liquid 

filling of R-600a and HC blends; can valve for refrigerant 

extraction; all necessary charging hoses including one 

special hose of 5 metre length and minimum inside 

diameter 15 mm, in order to prevent any R-600a gas in 

the working area; hose adapter for vacuum pump exhaust 

port connection; for safety reasons gas must be led 

through this hose into the outside. Including 2 litre of 

spare vacuum pump oil.

Portable HC charging set in aluminium case for accurate 

charging of refrigerant and air conditioning systems up to 

charge of 5 kg consisting of: > Digital scale > two quick 

coupler > extraction valve > PVC recovery hose 5m > two 

PVC charging hose 1.1m > ball valve > adapter for disposal 

refrigerant cylinder. Dimension of set 460*340*150 mm. 

Weight 5.2 kg
290

Descriptions of tools and equipment

Picture Technical Specification

Refillable refrigerant recovery cylinder equipped with 

double valve for liquid and vapour refrigerant transfer. 

Minimum capacity (water) 11.9 kg (26.2 lbs)

Meeting DOT-4BA-400 or ADR P200 standard

Set of nitrogen cylinder and pressure regulator DIN EN ISO 

2503; cylinder 20 litre and 300 bar, regulator pressure 

315/200 bar; working pressure 0-16/10 bar; inlet W24, 

32x1/14“ RH; outlet G1/4“ RH; adapter for 1/4" NPT refrigerant hose; refrigerant hose with ball valve 150cm long

R-600a refrigerant in cans with at least 400 g charge, 

purity ≥ 99.5% 

HC refrigerant blend (50% R-600a/50% R-290) in cans 

with at least a minimum of 150 g charge, thermodynamic 

similar pressures / temperatures as the CFC counterpart 

R-12, purity ≥ 99.5% 
291

APPENDIX 7: CONTENT FOR REFRIGERATION TRAINING STANDARD 

Introduction

This Appendix contains information relating to a set of competencies for technicians that work with any 

refrigerating system, to some extent. These were developed by the European Association of National Air 

Conditioning and Refrigeration Contractor Associations (AREA).46 AREA is the European organisation 

of air conditioning, refrigeration and heat pumps contractors, and was established in 1988. AREA 

voices the interests of 23 national members from 20 European countries, representing more than 9,000 

companies across Europe (mainly small to medium sized enterprises), employing some 125,000 people 

and with an annual turnover approaching € 20 billion.

Categorisation of ARC topics

GENERAL JOB DESCRIPTION OF THE AREA Refrigeration Craftsman “ARC”

Work environment The ARC works in different locations e.g. his company’s workshop, construction sites, retail shops, factories, industrial areas, ...

The type of installation, the equipment he works with and the complexity of 

the design vary with his specific order.

Most ARC work in small (3-10 persons) and medium (11-50 persons) size 

refrigeration contracting companies. These companies offer services in the 

fields of installation, sales, maintenance, repair, inspection and redesign 

of existing systems. The sub-sectors where they cover most activities, are 

primarily commercial refrigeration, industrial refrigeration and comfort air 

conditioning. Activities in transport refrigeration, refrigeration for process 

industries and mobile air conditioning are also performed but not so 

often.

Besides the refrigerating systems, the companies are involved in air 

treatment and electro-technical installations. They work generally countrywide but sometimes regionally or internationally. A substantial number 

of the refrigeration contracting companies are members of the national 

member associations of AREA.

Typical customers are retailers, wholesalers, cold storages, food and 

pharmaceutical/medical industries, agro-businesses, manufacturing 

industries and office buildings constructors or operators.

Work content With the help of work instructions, the ARC plans, prepares and performs 

the assembling of all parts of the refrigeration systems, which will be 

then commissioned and put into service. He also maintains, inspects, 

checks and repairs the refrigeration systems when there is a problem. He 

always controls his own work and records his tasks in the logbook linked 

to a specific installation. At all times he is respectful of the relevant 

requirements concerning the environment, quality, safety and energy 

efficiency. He is also involved at the end of life of the equipment.

Responsibilities The ARC is responsible for the preparation and the execution of his own 

tasks, in accordance with the work instructions that he received. He is not 

responsible for others or other people’s work, with the exception of his 

assistant(s). 

46 Further information can be found at www.area-eur.be 
292

GENERAL JOB DESCRIPTION OF THE AREA Refrigeration Craftsman “ARC”

Professional 

attitude

A certain amount of independence is expected from the ARC. He always 

gets his work instructions from his supervisor but most of the time he is 

alone on his way to a client and he performs his tasks independently of 

others.

Also the ARC has to have a sense of responsibility. He needs to strive for 

high quality in his work, and he must permanently be conscious of the 

importance of meeting the environmental and safety requirements.

Traditionally the ARC needs to have a service driven attitude, especially 

when he has to explain his work progress to the client or when he has to 

communicate with the client about the best possible work procedure in 

order not to interfere with the client’s company operations.

TRENDS

Market changes • In order to avoid an increase of the charge of the refrigerating fluid in a 

refrigeration system, more cascade and indirect systems are used. The 

use of environmentally friendly refrigerants is researched. There are 

related safety issues.

• The ARC will be even more service minded: there is a growing diversity 

services to customers, e.g. offering specific maintenance and lease 

contracts. Clients focus on their core business.

• The industry is trying to bring solutions to a recurrent shortage of 

qualified personnel in most countries.

• There are frequent mergers of refrigeration contracting companies.

• Globalisation: see below European harmonization

Regulations • There is a growing number of evolving rules about safety, health and 

consumer protection and environmental regulation, mainly European 

legislation; but also rules about quality, care and certification (e.g. 

PED, EN 378, and the F-gas regulations). Safety requirements concern 

refrigerants and installations. 

• Durability is now a well-established and sustained trend.

Technical and

technological 

developments

• The use of Ammonia as a refrigerant is increasing versus the F-gases. 

This will lead to changes in environment and safety directions (e.g. 

certification and other requirements of the F-gas Regulations).

• There are more indirect refrigeration installations: less refrigerant, 

distribution through secondary heat carrier and bigger pipeline systems. 

This affects design, assembling and maintenance operations.

• More standardized units and prefabricated parts will somewhat simplify 

assembling activities.

• Welding and connecting techniques are evolving, more TIG-welding.

• Developments occur in the field of measurement and control technique: 

less electrical and pneumatic parts, more electronic and mechanical 

instrumentation.

• Generally, we find better, larger and more sophisticated equipment, more 

precise instruments, faultfinding devices, digital logbooks and new 

communication means.
293

Organizational 

and management 

changes

• More regulations mean more administrative work and procedures. The ARC 

has more to report and in the office of the company, it brings more work to 

handle the procedures and to act on the results of the reports of the ARC.

European 

harmonization

• The mutual recognition and the free movement of goods increase cross 

border activities.

• The European legislation adapts itself to this situation to allow the 

Internal Market to be operational.

CORE ACTIVITIES OF THE AREA Refrigeration Craftsman

1

2

3

4

5

6

7

PRE-ASSEMBLY OF THE REFRIGERATION SYSTEM

INSTALLATION OF THE REFRIGERATION SYSTEM

REPORTS, CHECKS AND TECHNICAL ADMINISTRATION

COMMISSIONING 

MONITORING AND INSPECTION

FAULT FINDING AND REPAIR

DISMANTLING OF THE REFRIGERATION SYSTEM

CORE ACTIVITIES 1 PRE-ASSEMBLY OF THE REFRIGERATION SYSTEM

Process The ARC collects the instructions, material lists and drawings for the part 

of the installation that he has to pre-assemble. He checks the materials, 

equipment and instruments needed for his work. He makes sure that no 

moisture or dirt can enter the pre-assembly. 

Role and 

responsibilities

The ARC independently pre-assembles the refrigeration and electrotechnical system following the work instructions received. Most often this 

work is performed in the workshop of his company or in a workshop, on 

the customer’s location, under the supervision of a manager.

Complexity While performing this key task, the ARC follows the work instructions 

applicable to various recurring activities like electrical wiring, brazing of 

pipeline systems.

Involved with The ARC has to deal with supervisors, other colleagues and assistant(s).

Resources CTo properly perform, the ARC needs tools and equipment like work 

bench, bending devices, brazing materials

Quality of process 

and results

The ARC has to perform the task within the available time, according to 

the work instructions and following the legally prescribed procedures; he 

has to comply with the registration and administration documentation.

Choices and 

dilemmas

The ARC has to take into account that:

• he does not have an overview of the final place where the pre-fabricated 

part will be placed in the installation and how;

• a colleague should at any time be able to take over his work;

• a colleague should be able to place his pre-assembled part in the final 

installation. 
294

CORE ACTIVITIES 2 INSTALLATION OF THE REFRIGERATION SYSTEM

Process The ARC assembles refrigeration and/or air conditioning installations in 

accordance with his company’s directions, the project’s work instructions 

and the relevant drawings and diagrams. These are specific refrigerating 

systems (compressor, condenser, expansion valve, one or two evaporators, 

specific components). The materials are mentioned on a list which specifies the main components, copper pipes or other piping, electrical switches and wiring, instruments and flexible insulation materials.

Part of the needed materials can be taken from his service van. He 

checks the quantity against the quantity of the materials in his van at the 

start of the project. He discusses with the client about the work that he 

is going to perform and the interference that it may have in the customer’s company operations. Therefore the ARC should take into account the 

client’s operations when planning his work. 

Role and 

responsibilities

The ARC is responsible for:

• the good communication with the client

• the quality of his work and of his assistant’s work

• performing the job within the given timeframe

• the state-of-the-art installation of all parts in the refrigeration installation

Compexity The ARC has to take into account the interests of his own company as 

well as the interests of the client’s company. During his work, he has to 

comply with the safety and environmental aspects of the installation and 

the client’s company. He has to adapt his work to the circumstances on 

the site.

Involved with The ARC often works together with an assistant. He is also involved with the 

client organization, with personnel of subcontractors and personnel performing other tasks for the client.

Resources The ARC uses the tools that are put at his disposal by his employer or that 

he has specially rented

Quality of process 

and results

The ARC is expected to deliver the installation up and running as planned 

and designed for, and within the given timeframe. So the installation can 

contribute to the objectives of the client.

Choices and 

dilemmas

The ARC works on the client’s premises, the circumstances can be different and unforeseen changes can occur. This can influence the quality and 

the expected delivery date and the ARC has to react properly. He has 

constantly to take into consideration the client’s interests and his company’s interests. When interests are conflicting, he has to inform the 

involved party without causing commercial harm.
295

CORE ACTIVITIES 3 REPORTS, CHECKS AND TECHNICAL ADMINISTRATION

Process At all times the ARC should respect environmental, safety and health 

related legislation, especially after commissioning an installation. The 

installation has to be delivered as a safe, reliable and efficient product, 

following the EC marking requirements of the Machinery Directive. He 

works with different kinds of refrigerants and each has its own safety 

and environmental constraints, both nationally and internationally. The 

ARC is a key actor who has a great impact on the final result of the 

product or service supplied.

Role and 

responsibilities

The ARC is responsible for the correct assembling of the components and 

particularly valves according to the company’s directions and the technical instructions of the equipment installed. He is responsible for his own 

work and for the work of his assistant(s). He has to pay special attention 

to the piping work and the pipe connections by hard soldering or brazing.

Complexity As the ARC works on different sites, he should be able to perform his 

work under different and changing circumstances.

Involved with The ARC often works together with an assistant. He is also involved with 

the client organization, with personnel of subcontractors and personnel 

performing other tasks for the client

Resources The ARC receives from his employer the handbook directions and the work 

instructions. The employer is responsible for the personal qualification 

and certification of the ARC.

Quality of process 

and results

The ARC is expected to know the content of the work instructions and 

directions and to have the knowledge corresponding to his personal 

certificates.

Choices and 

dilemmas

The ARC could run into conflicting situations between his own company’s 

interests, the client’s company’s position and regulatory constraints.
296

CORE ACTIVITIES 4 COMMISSIONING

Process The installation is commissioned at the client’s site. During the building 

up of the installation, the Pressure Equipment Directive requirements have 

to be respected. The ARC checks the refrigerating system on the following 

items:

• electrical supply and electrical process control,

• leakage control through a pressure test,

• evacuating the system and vacuum testing so that there is no remaining 

moisture. 

The ARC should work according to the relevant regulations and should 

register all the data into a protocol.

The ARC fills the system with refrigerant. He does a second leakage 

check of the system.

He puts the refrigeration system into operation in accordance with the 

design conditions.

He registers all the data and figures in the logbook of the system.

The ARC makes a report for the client and his company and writes the 

transfer protocol.

Role and 

responsibilities

The ARC is responsible for putting into service on site the refrigeration 

system in accordance with the design conditions. He makes sure that all 

legal and company procedures are followed in the starting process.

Complexity The ARC takes into account that he works under the management of his 

company, but at the site of the client. The refrigeration system is sometimes a part of a whole production process of the client and he is only 

responsible for the refrigeration system so that he is depending on this 

production process.

Involved with The ARC is has to work in cooperation with supervisors of other companies on the same site of the client.

Resources The ARC has received his tools and equipment from his company to carry 

out his job.

Quality of process 

and results

The ARC is expected to deliver the installation in accordance with the 

design figures and at the right time, so that the installation can contribute 

to the goals of the client.

Choices and 

dilemmas

The ARC works on the client’s premises, the circumstances can be 

different and unforeseen changes can occur. This can influence the 

quality and the expected delivery date. The ARC has constantly to take 

into consideration the client’s interests and his company’s interests. 

When interests are conflicting, he has to inform the party involved without causing commercial harm.
297

CORE ACTIVITIES 5 MONITORING AND INSPECTION

Process The ARC is called by the client to check if the refrigerating system is 

working according to the design conditions. He has also to look if everything is respecting the safety and environmental regulations. The ARC has 

to write a report with his findings and conclusions and if necessary 

advise what the client has to do to bring the refrigeration system in good 

working conditions. A copy of his report goes to the installer company.

Role and 

responsibilities

The ARC is responsible for checking the refrigeration system according to 

the applicable directions and particularly for observing that there is no 

leakage. He is responsible for the content of his report and for coming to 

the right conclusions.

Complexity The ARC has a direct contact with the client, he understands the contractual and commercial relationship between his company and the client and 

the consequences thereof, but he has to do his job independently and 

consider only the real figures and the factual observations.

Involved with The ARC has to carry his task in good cooperation with the responsible 

person of the client organization.

Resources The ARC receives his tools and equipment from his company to carry out 

his job.

Quality of process 

and results

The ARC has to do his job while the installation is in operation without 

interrupting the working process of the client. The result must be to give 

to the client a reliable and good working refrigeration system for the 

future, so that the installation can contribute to the goals of the client.

Choices and 

dilemmas

The ARC has to do his job during the time that the installation is in 

service without interruption of the working process of the client, but that 

is not always possible. The ARC has to negotiate his working conditions 

with the client to allow him to work professionally as planned. When the 

ARC identifies a problem, he has to negotiate about the best solution, 

bearing in mind the commercial relation between the client and his 

company.
298

CORE ACTIVITIES 6 FAULT FINDING AND REPAIR

Process The ARC is called by the client to research and find the fault and to 

repair parts or components of the refrigeration system, because it is not 

working according to the design conditions or environmental and safety 

regulations. The ARC has to repair it as fast as possible and in a secured 

way. The ARC has to write a report explaining the results of his work and, 

if necessary, further advising what the client has to do to bring the 

refrigeration system in good condition for the future. A copy of his report 

goes to the installer company.

Role and 

responsibilities

The ARC is responsible for the results of his fault finding and repairing of 

the refrigeration system according to the information received and for 

checking that there is no leakage after his repair job, especially at the 

part/component repaired or replaced. He is responsible for the content of 

his report.

Complexity The ARC has a direct contact with the client, and he could feel some 

pressure arising from the commercial relation between his company and 

the client, but he has to do his job as soon as possible and following 

legal and regulatory directions.

Involved with The ARC has to carry his task with a good cooperating spirit and to 

negotiate with the responsible person of the client.

Resources The ARC receives his tools and equipment from his company to carry out 

his job.

Quality of process 

and results

The ARC has to work normally during the time when the installation is in 

operation, without interruption of the working process of the client, but 

most of the time that is not possible so he has to negotiate so that a 

minimum of productive time is lost during his intervention. The result 

must be to give to the client a reliable and good working refrigeration 

system for the future, so that the installation can contribute to the goals 

of the client.

Choices and 

dilemmas

The difficulty is to work during the time when the installation is in operation. The ARC has to do his job professionally and quickly. When the ARC 

discovers that it is not feasible to keep the refrigeration system running, 

he has to negotiate about the best solution even if it is conflicting with 

the commercial relation between the client and his company.
299

CORE ACTIVITIES 7 DISMANTLING OF THE REFRIGERATION SYSTEM

Process Before dismantling, the ARC recovers all the refrigerant and brings the 

refrigerant to a treatment plant in accordance with the applicable regulation. The ARC writes the necessary reports and gives a copy to his company, so they can register that the refrigeration system is out of operation 

and the recovered refrigerant has been taken care of.

Role and 

responsibilities

The ARC is responsible for the correct disassembling of the components 

and valves according to the company’s directions and the instructions 

linked to the equipment. He is responsible for his own work and for the 

work of his assistant. The most important contribution is to bring all the 

refrigerant safely out of the refrigeration system.

Complexity As the ARC works on different sites, he should be able to perform his 

work under different and changing circumstances, especially in this case 

where there is most of the time no commercial advantage and when the 

refrigeration system is generally in a poor condition.

Involved with The ARC has to carry his task with good cooperation and negotiate with 

the responsible person of the client, bearing in mind that there is no 

commercial interest.

Resources The ARC receives his tools, equipment and recycling cylinders from his 

company to carry out his task.

Quality of process 

and results

The ARC is expected to know the content of the work instructions and 

directions and to have the knowledge corresponding to his personal 

certificates The result has to be that there is no environmental pollution 

when he dismantles the refrigeration system.

Choices and 

dilemmas

The ARC could run into conflicting situations, being caught between his 

company, the client’s company and the applicable legislation due to the 

absence of commercial interest and the difficulty of handling a system in 

bad condition. 
300

360

Detailed ARC competence description 

The ARC is capable of giving a theoretical explanation about a basic compression refrigerating system

1 2 3 4 5 6 7

1.1.1

Know the basic ISO standard units as for temperature, pressure, mass, density, energy X X X X EN 13313

1.1.2

Understand basic refrigeration terms as: 

Superheat, High Side, Heat of Compression, Enthalpy, Refrigeration Effect, Low Side, Sub-cooling, Vapor Quality, Saturated Suction

X X X X EN 13313

1.1.3 Describe the lines of a Log P/h chart of a refrigerant X X X X EN 133131.1.4 Use the saturation tables of a refrigerant X X X X EN 133131.1.5 Draw a scheme of a single compression refrigeration cycle X X X X EN 133131.1.6

Describe the operation and function of the main components 

used in a refrigeration system as compressor, condenser, expansion valve, evaporator

X X X X X X EN 13313

1.1.7

Describe the operation and function of the following components used in a refrigeration system:

1.1.8 - Valves (ball valves, diaphragms, globe valves, relief valves) X X X X X X EN 133131.1.9 - Temperature and Pressure Controls X X X X X X EN 133131.1.10 - Sight Glasses and Moisture Indicators X X X X X X EN 133131.1.11 - Defrost Controls X X X X X X EN 133131.1.12 - System Protectors X X X X X X EN 133131.1.13 - Measuring Devices as manifold thermometer X X X X X EN 133131.1.14 - Oil Control Systems X X X X X X EN 133131.1.15 - Receivers X X X EN 133131.1.16 - Liquid and Oil Separators X X X EN 13313

The ARC explains "how the refrigeration system works" to a client.The ARC analyzes the operation of the refrigeration system and writes his conclusions in a report.

Job Competence Core Activities 

1.1 Basic Thermodynamics

Pre-assembly

Installation

Technical 

Reports

Commissioning

Monitoring

Fault Finding

Dismantling

Results

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

DescriptionSuccess Criteria
301

361

The ARC is capable of installing, putting into operation and carrying out the maintenance of reciprocating, screw and scroll compressors, single and two stage up to a power supply of 25 Kw. 

1 2 3 4 5 6 7

2.1.1 Explain the function of the compressor in the system X X X X X X X EN 13313

2.1.2 Explains the working of the compressor X X X X X X EN 133132.1.3 Explain the lubricating system of the compressor X X X X X EN 133132.1.4 Explain the capacity control of the compressor X X X X X EN 133132.1.5 Install the above mentioned different kinds of compressors X X X prEN 378-2 art. 5.12.1.6 Connect the safety and control switches X X X prEN 378-2 art. 5.12.1.7 Install the suction and discharge valves X X X prEN 378-2 art. 5.12.1.8 Install the oil return system X X X prEN 378-2 art. 5.12.1.9 Start up and shut down these kinds of compressors X X X X X X prEN 378-2 art. 6.32.1.10 Do measurements during operation of compressor X X X X X prEN 378-4 art. 5 2.1.11 Check the good working condition of the compressor X X X X X prEN 378-4 art. 5 2.1.12 Write a report about the condition of the compressor X X X X X prEN 378-4 art. 4.32.1.13 Take the decision to repair the compressor X X X X prEN 378-4 art. 4.32.1.14 Take the decision to replace the compressor X X X prEN 378-4 art. 4.3

A perfectly working compressor contributes to a low energy consumption and a reliable performance as planned for the client.

Job Competence Core Activities 

2.1 Component: Compressor

Pre-assembly

Installation

Technical

Reports

Commissioning

Monitoring

Fault Finding

Dismantling

Results

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

DescriptionSuccess Criteria
302

362

The ARC is capable of installing, putting into operation and carrying out the maintenance of air cooled and water cooled condensers. 

1 2 3 4 5 6 7

2.2.1 Explain the function of the condenser in the system X X X X X X X EN 13313

2.2.2 Explain the working of the condenser X X X X X X EN 133132.2.3 Adjust a discharge pressure control of the condenser X X X X X EN 133132.2.4 Install the above mentioned types of condensers X X X prEN 378-2 art. 5.12.2.5 Connect the safety and control switches X X X prEN 378-2 art. 5.12.2.6 Install the discharge and liquid lines in the correct position X X X prEN 378-2 art. 5.12.2.7 Purge non condensable gases out of the condenser X X X prEN 378-2 art. 5.12.2.8 Start up and shut down all types of condensers X X X X X X prEN 378-2 art. 6.32.2.9 Do measurements during operation of the refrigeration system X X X X X prEN 378-4 art. 42.2.10 Check the good working condition of the condenser X X X X X prEN 378-4 art. 42.2.11 Check the surface of the condenser X X X X X prEN 378-4 art. 42.2.12 Write a report about the condition of the condenser X X X X X prEN 378-4 art. 4.32.2.13 Take the decision to repair a part of the condenser X X X prEN 378-4 art. 4.32.2.14 Take the decision to replace the condenser X X X prEN 378-4 art. 4.3

A perfectly working condenser contributes to a low energy consumption and a minimum of heat load to the environment. 

Results

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

DescriptionSuccess Criteria

Job Competence Core Activities 

2.2 Component: Condenser

Preassembly

Installation

Technical

Reports

Commissioning

Monitoring

Fault

Finding

Dismantling
303

363

The ARC is capable of installing, putting into operation and carrying out the maintenance of air cooled and liquid cooled evaporators.

1 2 3 4 5 6 7

2.3.1 Explain the function of the evaporator in the system X X X X X X X EN 13313

2.3.2 Explain the working of the evaporator X X X X X X EN 133132.3.3 Explain the several ways of defrosting the evaporator X X X X X EN 133132.3.4 Adjust an evaporating pressure control of the evaporator X X X X X prEN 378-2 art. 5.12.3.5 Install the above mentioned kinds of evaporators X X X prEN 378-2 art. 5.12.3.6 Connect the safety and control switches X X X prEN 378-2 art. 5.12.3.7 Install the liquid and suction pipelines in the correct position X X X prEN 378-2 art. 5.12.3.8 Install the hot gas defrost pipeline in the right position X X X prEN 378-2 art. 5.12.3.9

Install the hot gas pipeline to protect a watercooled evaporator against low evaporation pressure X X X X X X prEN 378-2 art. 5.1

2.3.10 Start up and shut down all kinds of evaporators X X X X X prEN 378-2 art. 6.32.3.11 Do measurements during operation of the refrigeration system X X X X X prEN 378-4 art. 42.3.12 Check the good working condition of the evaporator X X X X X prEN 378-4 art. 42.3.13 Check the surface of the evaporator X X X X X prEN 378-4 art. 42.3.14 Write a report about the condition of the evaporator X X X X prEN 378-4 art. 4.32.3.15 Take the decision to repair a part of the evaporator X X X prEN 378-4 art. 4.32.3.16 Take the decision to replace the evaporator X X X prEN 378-4 art. 4.3

A perfectly working evaporator contributes to a low energy consumption and a reliable performance as planned for the client.

Results

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

DescriptionSuccess Criteria

Job Competence Core Activities 

2.3 Component: Evaporator

Preassembly

Installation

Technical

Reports

Commissioning

Monitoring

Fault

Finding

Dismantling
304

364

The ARC is capable of installing, putting into operation and servicing Thermostatic Expansion Valves (TEV) and other components.

1 2 3 4 5 6 7

2.4.1 Explain the function of a TEV in the system X X X X EN 13313

2.4.2 Explain the working of a TEV in the system X X X X EN 133132.4.3

Explain the working principle of different kinds of expansion regulators X X X X EN 13313

2.4.4 Fit a mechanical and electronic TEV X X X prEN 378-2 art. 5.12.4.5 Adjust a mechanical and electronic TEV X X X prEN 378-2 art. 5.12.4.6 Fit and adjust mechanical and electronic thermostats X X X X prEN 378-2 art. 5.12.4.7 Fit and adjust mechanical and electronic pressure limiter X X X X prEN 378-2 art. 5.12.4.8 Fit and check the working of an oil seperator X X X X X prEN 378-2 art. 5.12.4.9 Fit a liquid receiver X X prEN 378-2 art. 5.12.4.10 Fit a sightglass and check the condition of the refrigerant X X X X X prEN 378-2 art. 5.12.4.11 Fit a filter dryer and check the condition of the dryer X X X X X prEN 378-2 art. 5.12.4.12 Fit and check a solenoid valve X X X X X prEN 378-2 art. 5.12.4.13 Fit a stop valve X X prEN 378-2 art. 5.12.4.14 Fit and adjust a pressure regulated valve X X X X prEN 378-2 art. 5.12.4.15 Write a report about the condition of the TEV or component X X X X prEN 378-4 art. 4.32.4.16 Take the decision to repair a part of the TEV or component X X X prEN 378-4 art. 4.32.4.17 Take the decision to replace the TEV or component X X X prEN 378-4 art. 4.3

A perfectly working TEV contributes to a low energy consumption, and a good performance as planned for the client.A perfectly fitted and adjusted component contributes to the optimal working of the system.

Job Competence Core Activities 

2.4 Expansion valves & other components

Preassembly

Installation

Technical

Reports

Commissioning

Monitoring

Fault

Finding

Dismantling

Results

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

DescriptionSuccess Criteria
305

365

The ARC is capable of building a leak tight copper piping system in a refrigeration installation.

1 2 3 4 5 6 7

3.1.1

Work with copper tubes from a diameter of 1⁄4” (6mm) till 7/8” (28mm) and from 35 mm till 54 mm. X X X X prEN378-2 art. 6.2

3.1.2 In particular in the following ways:3.1.3 - flared joints diameter of 1⁄4”(6mm) till 3/4” (18mm) X X X X prEN378-2 art. 6.23.1.4

- bends of copper tubes diameter of 1⁄4”(6mm) till 3/4” (18mm). X X X X

3.1.5

- fixed connections by hard soldering diameter 1⁄4” (6mm)

till 7/8” (28mm) and from 35 mm till 54 mm. X X X X EN 13133

3.1.6 Make hard soldering joints for the following connections:3.1.7 • copper-copper X X X EN 131333.1.8 • copper-steel X X X EN 131333.1.9 • copper-brass X X X EN 131333.1.10 Install valves in the correct position X X X prEN 378-2 art. 5.13.1.11 Install solenoid, control valves and other devises in pipelines X X X prEN 378-2 art. 5.03.1.12 Install flexible insulation X X prEN 378-2 art. 5.13.1.13 Make pipe supports X X X prEN378-2 art. 6.33.1.14 Perform a strength pressure test X X X prEN378-2 art. 6.33.1.15 Perform a tightness test X X X prEN378-2 art. 6.33.1.16 Perform a functional test X X X prEN378-2 art. 6.33.1.17 Perform a conformity test of the complete installation X X prEN378-2 art. 6.3

Safe and environmentally friendly refrigeration piping system without leakage by starting upEnvironmentally friendly refrigeration piping system without leakage during operation

3.1 Piping

DescriptionSuccess CriteriaResults

Core Activities 

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

Job Competence

Commissioning

Monitoring

Fault

Finding

Dismantling

Installation

Technical

Reports

Preassembly
306

366

The ARC is capable of installing the electrical cabling and wiring of a refrigeration system.

1 2 3 4 5 6 7

4.1.1 Explain the use of different kinds of cables an wires X X X EN 50110 art.3.2.4

4.1.2 Explain the use of different kinds of classified connections X X X EN 50110 art.3.2.44.1.3 Explain the use of different kinds of classified IP X X X EN 50110 art.3.2.44.1.4 Explain the different kinds of safety fuses and switches X X X X EN 50110 art.3.2.44.1.5 Install electrical equipment and motors X X EN 50110 art.6.24.1.6 Lay cables in the cable routes X X X EN 50110 art.6.24.1.7 Do the wiring of a switch panel X X X X EN 50110 art.6.24.1.8 Connect the power supply at the main switch panel X X X EN 60204-14.1.9 Connect a single and or three phase motor X X X EN 50110 art.6.24.1.10 Connect the electrical components X X X X EN 50110 art.6.24.1.11

Check the electrical safety according to the EU and National regulations X X X EN 50110 art.5.3

4.1.12 Check the power consumption of a motor X X X EN 50110 art.5.34.1.13 Measure the electrical equipment and cabling X X X X EN 50110 art.5.34.1.14 Adjust the electrical safety switches X X EN 50110 art.5.34.1.15 Adjust the electrical equipment X X EN 50110 art.5.34.1.16 Check the rotation direction of a motor X X EN 50110 art.5.34.1.17 Take the decision to repair an electrical component X X X EN 133134.1.18 Take the decision to replace an electrical component X X X EN 133134.1.19 Write a report about the electrical equipment X X X X EN 13313

A safe environment for the client and his personnelA reliable electrical system 

Job Competence Core Activities 

4.1 Electricity

Preassembly

Installation

Technical

Reports

Commissioning

Monitoring

Fault

Finding

Dismantling

Results

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

DescriptionSuccess Criteria
307

367

Job Competence

The ARC is capable of measuring and analyzing physical data, and of making a correct diagnosis.

1 2 3 4 5 6 7

Success Criteria

5.1.1 Use a manometer set X X X X EN 13313

5.1.2 Use a thermometer X X X EN 133135.1.3 Use a Torr gauge X X X EN 133135.1.4 Use scales to weight refrigerant X X X X EN 133135.1.5 Use a airflowmeter X X X EN 133135.1.6 Use an acid test kit to check an oil sample X X X EN 133135.1.7 Use a recovery set X X X EN 133135.1.8 Handle a refrigerant cylinder X X X EN 133135.1.9 Drain oil out of a system X X X EN 133135.1.10 Use a multimeter for measuring Volt/Amp/Ohm X X X EN 133135.1.11 Use an electronic leak detection device X X X EN 133135.1.12 Use a vacuumpump X X EN 133135.1.13 Place the data in a Log P/h diagram X X X EN 133135.1.14 Place the data in a h/x diagram X X X EN 133135.1.15 Use product information X X X EN 133135.1.16 Use a computer programme to control the system X X X EN 133135.1.17

Write a report based on the results of the measurements and draw the right conclusions X X X X F-gases regulation

Results

Correct information about the condition of the system at the time of measuring / analyzing, to be recorded to allow historical review and future use

5.1 Measurements and Analysis 

Description

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

Core Activities 

Preassembly

Installation

Technical

Reports

Commissioning

Monitoring

Fault

Finding

Dismantlin g
308

368

The ARC is capable of informing a client about the working procedures and the use of the refrigeration system.

1 2 3 4 5 6 7

6.1.1 Arrange an appointment with the client X X X X X F-gas regulation

6.1.2

Properly inform the client about the method of operation of the refrigeration system X X X X X prEN 378-4 Art. 4.2

6.1.3 Consider the client's wishes X X X X F-gas regulation6.1.4 Advise the client about maintenance planning X X X F-gas regulation6.1.5 Advise the client on saving energy X X X X F-gas regulation6.1.6 Make the client aware of environmental issues X X X X X F-gas regulation6.1.7 Advise the client on safety issues X X X X prEN 378-4 Art. 4.26.1.8 Process client complaints X X X F-gas regulation6.1.9

Advise the client with regard to shutting down the refrigeration system X X X X F-gas regulation

6.1.10

Advise the client whether a new system, or the repair of components, is required X X F-gas regulation

6.1.11 Explain to the client the work procedures X X X X F-gas regulation6.1.12 Explain to the client the content of a report X X X X X F-gas regulation

The client has received the necessary information about the system installed,at different times of its life cycle, and understands the performance that he can expect in the future.

Job Competence Core Activities 

6.1 Communication

Preassembly

Installation

Technical

Reports

Commissioning

Monitoring

Fault

Finding

Dismantling

Results

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

DescriptionSuccess Criteria
309

369

The ARC is capable of handling the refrigeration system in a way that there is no loss of refrigerant and its working is safe.

1 2 3 4 5 6 7

7.1.1 Be aware and know the environmental and safety regulations X X X X X X X prEN378-4 art. 4.1

7.1.2 Carry out a pressure test to check the strength of the system X X prEN378-1 art. 6.3.37.1.3 Carry out a pressure test to check the tightness of the system X X X prEN378-1 art. 6.3.47.1.4 Evacuate the system to a level 270 Pa X X X prEN378-4 art. 5.37.1.5 Fill the system with refrigerant without loss of refrigerant X X X prEN378-4 art. 5.47.1.6 Control the charge of refrigerant X X X X prEN378-4 art. 5.47.1.7 Do a visual inspection of the whole system especially the joints X X X X X prEN378-4 art. 5.17.1.8 Do a leak test of the system X X X X prEN378-4 art. 5.17.1.9 Fill in the data in the logbook X X X X prEN378-1 art. 6.4.2.57.1.10 Fill in the certificate of the pressure test X X X prEN 378-4 art. 4.37.1.11 Fill in the certificate of the evacuation test X X X prEN 378-4 art. 4.37.1.12 Fill in the certificate of the tighness/leak test X X X X prEN 378-4 art. 4.37.1.13 Fill in a report with starting up figures X X X prEN 378-4 art. 4.37.1.14 Fill in a report with operational figures X X X X prEN 378-4 art. 4.37.1.15 Fill in the report about the refrigerant used X X X prEN 378-4 art. 4.37.1.16 Fill in the document for removing dirty refrigerant X X X prEN 378-4 art. 4.37.1.17 Fill in the report about the refrigerant removed out of a system X X X prEN 378-4 art. 4.37.1.18 Fill in a report of dismantling of the system X X F-gas regulation

Strict minimum emission of refrigerantThe environmental auditors can monitor the history of the system.

Job Competence Core Activities 

7.1 Environmental and safety regulations

Preassembly

Installation

Technical 

Reports

Commissioning

Monitoring

Fault 

Finding

Dismantling

Results

The National Authorities to certify 

Qualification have to make sure that 

European and National Regulations, 

Directives and Norms are complied with 

particular as mentioned below 

DescriptionSuccess Criteria
310

Learning outcome

(The learner will...)

Assessment criteria

(The learner can...)

(I)

Understand the specific 

health and safety 

requirements which 

apply to the installation, 

servicing and maintaining 

and de-commissioning 

of HC RAC systems

• Identify the hazards associated with HC refrigerants: Flammability, 

low boiling point, asphyxiation (heavier than air), LFL, UFL, sources 

of ignition, practical limits, density 

• State and identify the commonly used refrigerant designations

• State the requirements of HC specific risk assessments

• Identify appropriate fire extinguishers for work on HC RAC systems

(II)

Understand the legislative and organisational procedures for 

installation, servicing 

and maintaining and 

de-commissioning of 

HC RAC systems

• State the appropriate sources of health and safety information when installing, servicing and maintaining and de-commissioning of RAC systems

• State the regulations, codes of practice, and industry recommendations appropriate to the installation, servicing and maintaining and 

de-commissioning of RAC systems, including working with refrigerants

• State the occupancy classifications and charge size limitations for 

refrigeration systems

• State charge size limitations for human comfort cooling and heating 

for air conditioning systems

(III)

Understand the 

differences between 

Halocarbon and HC 

RAC systems

• Identify the specific system features and components which apply to 

HC systems: electrical devices, electrical enclosures, associated 

electrical devices (including halocarbon systems), compressors 

(including starter and associated electrics) 

• Identify the features and characteristics of: critical charge systems, 

oil compatibility, state the properties, advantages and disadvantages 

of HC refrigerants, including:

 - Leakage implications (direct and indirect)

 - Thermodynamic properties

 - Cooling capacity and energy efficiency

 - Density

 - Not stenched

• Explain why HCs are not suitable for retro-filling into halocarbon systems

• Identify typical applications of HC RAC systems: integral (plug in 

systems), fluid chillers, high stage CO2 cascade systems, split AC 

systems, domestic fridge freezers (isobutane)

(IV)

Understand the procedures for planning and 

preparing for work on 

HC RAC systems

• State the requirements for completing a risk assessment for work on 

HC RAC systems

• State the requirements for creating and maintaining a safe working 

area, including requirements for temporary zoning

• Identify appropriate tools and equipment for work on HC RAC systems

(V)

Be able to plan and 

prepare for work on 

HC RAC systems

• Complete a location specific risk assessment (using a dynamic risk 

assessment template) 

• Establish and maintain a safe working area

• Select appropriate tools, equipment and PPE for work on HC RAC systems

APPENDIX 8: EXAMPLE ASSESSMENT CRITERIA FOR TECHNICIANS
311

Learning outcome

(The learner will...)

Assessment criteria

(The learner can...)

(VI)

Understand the 

specific requirements 

for installing and 

testing HC RAC 

systems

• Identify occupancy class

• Identify the maximum refrigerant charge based on occupancy class

• Calculate the maximum charge based on the practical limit 

• Determine from calculations the system specific maximum charge

• State the methods and procedures for: strength integrity testing, 

tightness testing, leak testing, evacuation and dehydration

• State the procedures for charging HC refrigerants into systems

• State the procedures for determining when charge is correct

• State the records to be completed prior to handover

• State the requirements for safely labelling HC RAC systems

• Specify the information that should be provided to customers, including: operation of system and controls, using only appropriately trained 

servicing personnel, restrictions on the relocation of equipment

(VII)

Understand the 

differences between 

halocarbon and HC 

service and maintenance procedures

• Identify appropriate ‘like for like’ replacement components for 

the following: electrical devices, electrical enclosures, associated 

electrical devices (including halocarbon systems), compressors 

(including starter and associated electrics) 

• State the importance of maintaining the integrity of sealed electrical 

enclosures

• State appropriate methods for accessing and sealing HC systems

• Specify the requirements for recovering HC refrigerants, including 

situations when it may be safe to vent refrigerant to atmosphere

• State the requirements for the safe use of vacuum pumps when 

evacuating HC systems

(VIII)

Be able to service 

and maintain HC RAC 

systems

• Calculate the safe fill weight for the recovery cylinder (density 

difference between HFCs and HCs)

• Connect equipment in preparation for recovery 

• Recover HC refrigerant to a prescribed pressure

• Fill the system with nitrogen to a prescribed pressure and release 

to atmosphere

• Un-braze specified component 

• Re-braze specified component while purging nitrogen through pipework

• Pressure test joints (containment)

• Evacuate to below 2000 microns

• Re-charge with specified refrigerant weight

• Run system and check operation

• Remove charging equipment

• Seal system and complete leak test with appropriate equipment

• Complete service records as appropriate

(IX)

Understand the 

decommissioning 

procedures for HC

RAC systems

• Identify the safe procedures for handling potentially hazardous 

system materials, including: HC refrigerants 

• Identify work sequences for decommissioning and making safe a 

system in accordance with appropriate industry procedures
312

APPENDIX 9: RECORD SHEET FOR REFRIGERANT USE

379

APPENDIX 9: RECORD SHEET FOR REFRIGERANT USE

RECORD	
  SHEET	
  FOR	
  HYDROCARBON	
  REFRIGERATION/AIR	
  CONDITIONING	
  PLANT

General	
  information

Plant	
  name Reference	
  no.

Location	
  of	
  plant

Plant	
  operator	
  (name,	
  address,	
  telephone)

Operator	
  contact	
  person

Cooling/heating	
  loads	
  served

Plant	
  manufacturer Year	
  of	
  installation

Refrigerant	
  type Refrigerant	
  quantity

Refrigerant	
  additions

Date Company/personnel/registration	
  no. Amount	
  added	
  (kg) Reason	
  for	
  addition

Refrigerant	
  removals

Date Company/personnel/registration	
  no. Amount	
  removed	
  (kg) Reason	
  for	
  removal

Leak	
  checks

Date Company/personnel/registration	
  no. Result	
  (location	
  and	
  leak	
  causes) Follow-­‐up	
  actions	
  required

Checks	
  to	
  electrical	
  components/potential	
  sources	
  of	
  ignition

Date Company/personnel/registration	
  no. Result	
  (faulty	
  items,	
  corrections) Follow-­‐up	
  actions	
  required

Checks	
  to	
  automatic	
  detection	
  and	
  emergency	
  equipment	
  (if	
  applicable)

Date Company/personnel/registration	
  no. Result	
  (faulty	
  items,	
  corrections) Follow-­‐up	
  actions	
  required

Follow-­‐up	
  actions

Date Company/personnel/registration	
  no. Related	
  to	
  testing/checks	
  on Actions	
  taken
313

APPENDIX 10: VAPOUR PRESSURE AND LIQUID DENSITY TABLES

In order to determine test and working pressures of system components and assemblies, it is important to 

have data on the pressure-temperature relationship of the refrigerant. Data for five HC refrigerants are 

provided here, encompassing a typical temperature range.

• R600a

• R290

• R1270

• R290 (94% mol) / R170 (6% mol) blend

• R290 (50% mol) / R600a (50% mol) blend

The data has been generated using Refprop version 847 , where data for other HCs and their mixtures 

can be obtained.

Table of vapour pressure and liquid density

374

APPENDIX 10: VAPOUR PRESSURE AND LIQUID DENSITY TABLES 

In order to determine test and working pressures of system components and assemblies, it is 

important to have data on the pressure-temperature relationship of the refrigerant. Data for five HC 

refrigerants are provided here, encompassing a typical temperature range. 

 R600a 

 R290 

 R1270 

 R290 (94% mol) / R170 (6% mol) blend 

 R290 (50% mol) / R600a (50% mol) blend 

The data has been generated using Refprop version 8 45, where data for other HCs and their 

mixtures can be obtained. 

Table of vapour pressure and liquid density 

R600a (isobutane) R290 (propane) R1270 (propylene) R290/R170 blend R290/R600a blend Temperature Vapour 

pressure 

Liquid 

density 

Vapour 

pressure 

Liquid 

density 

Vapour 

pressure

Liquid 

density 

Vapour 

pressure

Liquid 

density 

Vapour 

pressure

Liquid 

density 

°C kPa kg/m3 kPa kg/m3 kPa kg/m3 kPa kg/m3 kPa kg/m3

-40 28 625 111 579 142 599 148 574 68 604 

-39 30 624 116 578 148 598 154 573 71 603 

-38 32 623 121 577 154 597 160 572 74 602 

-37 33 621 126 575 161 596 166 571 77 601 

-36 35 620 132 574 167 594 173 570 80 600 

-35 37 619 137 573 174 593 179 569 84 599 

-34 38 618 143 572 182 592 186 567 88 598 

-33 40 617 149 571 189 590 193 566 91 597 

-32 42 616 155 570 196 589 201 565 95 595 

-31 44 615 161 568 204 588 208 564 99 594 

-30 46 614 168 567 212 586 216 562 104 593 

-29 49 613 174 566 221 585 224 561 108 592 

-28 51 612 181 565 229 584 232 560 112 591 

-27 53 611 188 564 238 583 241 559 117 590 

-26 56 610 196 562 247 581 249 558 122 589 

-25 58 609 203 561 256 580 258 556 126 588 

-24 61 608 211 560 266 579 267 555 131 586 

-23 63 606 219 559 275 577 277 554 137 585 

-22 66 605 227 557 286 576 286 553 142 584 

-21 69 604 236 556 296 574 296 551 147 583 

-20 72 603 244 555 307 573 306 550 153 582 

-19 75 602 253 554 317 572 317 549 159 581 

-18 78 601 263 552 329 570 327 547 165 579 

 

45 http://www.nist.gov/srd/nist23.htm

47 http://www.nist.gov/srd/nist23.htm
314

375

R600a (isobutane) R290 (propane) R1270 (propylene) R290/R170 blend R290/R600a blend Temperature Vapour 

pressure 

Liquid 

density 

Vapour 

pressure 

Liquid 

density 

Vapour 

pressure

Liquid 

density 

Vapour 

pressure

Liquid 

density 

Vapour 

pressure

Liquid 

density 

°C kPa kg/m3 kPa kg/m3 kPa kg/m3 kPa kg/m3 kPa kg/m3

-17 82 600 272 551 340 569 338 546 171 578 

-16 85 599 282 550 352 568 349 545 177 577 

-15 89 598 292 549 364 566 361 544 184 576 

-14 92 596 302 547 377 565 373 542 190 575 

-13 96 595 312 546 389 563 385 541 197 574 

-12 100 594 323 545 402 562 397 540 204 572 

-11 104 593 334 543 416 561 410 538 211 571 

-10 108 592 345 542 429 559 423 537 219 570 

-9 112 591 357 541 444 558 436 536 226 569 

-8 117 590 369 539 458 556 450 534 234 568 

-7 121 589 381 538 473 555 463 533 242 566 

-6 126 587 393 537 488 553 478 532 250 565 

-5 131 586 406 535 503 552 492 530 259 564 

-4 136 585 419 534 519 551 507 529 267 563 

-3 141 584 433 533 535 549 522 528 276 561 

-2 146 583 446 531 552 548 538 526 285 560 

-1 151 582 460 530 569 546 554 525 294 559 

0 157 580 475 529 586 545 570 523 304 558 

1 162 579 489 527 604 543 586 522 314 556 

2 168 578 504 526 622 542 603 521 324 555 

3 174 577 520 525 640 540 620 519 334 554 

4 180 576 535 523 659 539 638 518 344 553 

5 186 575 551 522 678 537 656 516 355 551 

6 193 573 568 520 698 536 674 515 366 550 

7 199 572 584 519 718 534 693 513 377 549 

8 206 571 602 518 739 532 712 512 388 548 

9 213 570 619 516 760 531 732 511 400 546 

10 220 569 637 515 781 529 752 509 412 545 

11 228 567 655 513 803 528 772 508 424 544 

12 235 566 674 512 825 526 793 506 437 542 

13 243 565 693 510 848 525 814 505 449 541 

14 251 564 712 509 871 523 835 503 462 540 

15 259 562 732 507 895 521 857 502 476 538 

16 267 561 752 506 919 520 880 500 489 537 

17 275 560 773 504 943 518 902 499 503 536 

18 284 559 794 503 968 516 926 497 517 534 

19 293 557 815 501 994 515 949 496 532 533 

20 302 556 837 500 1020 513 973 494 546 532 

21 311 555 859 498 1046 511 998 492 561 530 

22 321 554 882 497 1073 510 1023 491 577 529 

23 330 552 905 495 1101 508 1048 489 592 528 

24 340 551 928 494 1129 506 1074 488 608 526 

25 350 550 952 492 1158 504 1101 486 624 525 

26 361 549 977 490 1187 503 1127 484 641 523 

27 371 547 1002 489 1216 501 1155 483 658 522 

28 382 546 1027 487 1246 499 1182 481 675 521 

29 393 545 1053 486 1277 497 1211 480 692 519 
315

376

R600a (isobutane) R290 (propane) R1270 (propylene) R290/R170 blend R290/R600a blend Temperature Vapour 

pressure 

Liquid 

density 

Vapour 

pressure 

Liquid 

density 

Vapour 

pressure

Liquid 

density 

Vapour 

pressure

Liquid 

density 

Vapour 

pressure

Liquid 

density 

°C kPa kg/m3 kPa kg/m3 kPa kg/m3 kPa kg/m3 kPa kg/m3

30 405 543 1079 484 1308 496 1239 478 710 518 

31 416 542 1106 482 1340 494 1269 476 728 516 

32 428 541 1133 481 1373 492 1298 474 747 515 

33 440 539 1161 479 1405 490 1329 473 766 514 

34 452 538 1189 477 1439 488 1360 471 785 512 

35 465 537 1218 476 1473 486 1391 469 804 511 

36 477 535 1247 474 1508 484 1423 468 824 509 

37 490 534 1277 472 1543 483 1455 466 845 508 

38 504 533 1307 471 1579 481 1488 464 865 506 

39 517 531 1338 469 1615 479 1521 462 886 505 

40 531 530 1370 467 1652 477 1555 460 907 503 

41 545 529 1401 465 1690 475 1590 459 929 502 

42 559 527 1434 464 1728 473 1625 457 951 500 

43 574 526 1467 462 1767 471 1660 455 974 499 

44 589 524 1500 460 1807 469 1697 453 997 497 

45 604 523 1534 458 1847 467 1733 451 1020 496 

46 620 522 1569 456 1888 464 1771 449 1043 494 

47 635 520 1604 454 1929 462 1809 447 1067 492 

48 652 519 1640 452 1972 460 1847 445 1092 491 

49 668 517 1676 450 2014 458 1886 443 1117 489 

50 685 516 1713 449 2058 456 1926 441 1142 488 

51 702 515 1751 447 2102 454 1966 439 1167 486 

52 719 513 1789 445 2147 451 2007 437 1193 484 

53 736 512 1828 443 2193 449 2049 435 1220 483 

54 754 510 1867 441 2239 447 2091 433 1247 481 

55 773 509 1907 438 2286 444 2134 431 1274 480 

56 791 507 1948 436 2334 442 2177 429 1302 478 

57 810 506 1989 434 2382 440 2222 426 1330 476 

58 829 504 2031 432 2432 437 2266 424 1359 474 

59 849 503 2073 430 2482 435 2312 422 1388 473 

60 869 501 2117 428 2532 432 2358 420 1417 471 




Deutsche Gesellschaft für 

Technische Zusammenarbeit (GTZ) GmbH

- German Technical Cooperation –

Programme Proklima

Dag-Hammarskjöld-Weg 1– 5

65760 Eschborn / Germany 

T +49 61 96 79 - 1022

F +49 61 96 79 - 80 1022

E proklima@gtz.de

I www.gtz.de

The purpose of this publication is to present the existing information and 

guidance relating to the safe use of hydrocarbon refrigerants, but also to inform 

in a comprehensive manner such that all of the stages in the system life are 

covered in an interlinked way. It is recognised that simply describing technical 

requirements is not always sufficient in itself to ensure that a high level of 

safety is achieved; introducing a robust infrastructure is equally important. For 

example, how government or industry bodies may set up schemes for certification of technician training, or how manufacturers, distributors or contracting 

companies may organise their quality management systems to help with the 

ongoing improvement of safety levels, etc, are all important considerations.

This handbook shall function as a guidebook for policy-makers involved with 

designing nation-wide policies to support the use of natural refrigerants 

(i.e. regulatory aspects, standards, etc) and also for manufactures and installers 

of HCFC and HFC equipment to reliably assess the suitability of hydrocarbon 

options and subsequently implement them.

GTZ Proklima teamed up with TÜV SÜD to ensure that the safety system is 

described from both angles, both from a third party perspective and that of an 

implementing agency. Both organisations work with implementation of flammable refrigerants and they have joined forces to develop these guidelines.