TECHNICAL NOTE

ORIGINATOR Daniel Colbourne

REFERENCE CTN-107

DATE ISSUED

SUBJECT Guidelines on ATEX Directive (Equipment)

Introduction

Equipment and Protective systems intended for use in a potentially Explosive Atmospheres 

"ATEX" Directive 94/9/EC provides the technical requirements to be applied to equipment 

intended for use in potentially explosive atmospheres 1. It is a product directive and covers a 

large range of equipment, potentially including equipment used on fixed offshore platforms, in

petro-chemical plants, mines, flourmills and other areas where a potentially explosive 

atmosphere may be present. The Directive has been mandatory from 1st July 2003. In very 

broad terms, there are three pre-conditions for the Directive to apply:

1. The equipment must be capable of being a source of ignition; 

2. Be intended for use in a potentially explosive atmosphere; and be 

3. Under normal atmospheric conditions. 

The Directive also covers components essential for the safe use and safety devices directly 

contributing to the safe use of the equipment in scope. These devices may be outside the 

potentially explosive environment.

The implications of falling under the scope of ATEX are that significant efforts are needed to 

demonstrate that the equipment conforms to all relevant essential safety requirements of the 

directive. In certain cases, it may be necessary to employ third party testing and approvals. It 

is the responsibility of any manufacturer of equipment to fully read and understand the 

directive, to be able to determine whether their equipment falls under its scope.

In general, it is preferable to remain outside the scope of the ATEX directive, as inclusion 

obliges the manufacturer to employ electrical components rated for hazardous atmospheres, 

and the operator and service persons are subject to the requirements of Directive 

1999/92/EC. A means to avoid inclusion under ATEX are detailed below.

 

1 Directive 1999/92/EC on minimum requirements for improving the safety and health protection of 

workers potentially at risk from explosive atmospheres is not addressed here.
Scope

Article 1 of the Directive provides the scope, which states that the Directive applies only to 

equipment and protective systems intended for use in potentially explosive atmospheres, 

provided it is capable of being its own potential source of ignition. These include:

− 'Equipment' meaning machines, apparatus, fixed or mobile devices, control 

components and instrumentation thereof and detection or prevention systems which, 

separately or jointly, are intended for the generation, transfer, storage, measurement, 

control and conversion of energy for the processing of material and which are 

capable of causing an explosion through their own potential sources of ignition.

− 'Protective systems' meaning design units which are intended to halt incipient 

explosions immediately and/or to limit the effective range of explosion flames and 

explosion pressures. Protective systems may be integrated into equipment or 

separately placed on the market for use as autonomous systems.

− 'Components' meaning any item essential to the safe functioning of equipment and 

protective systems but with no autonomous function.

The directive identifies equipment groups and categories. Equipment group I applies to 

equipment intended for use in underground parts of mines and Equipment group II applies to 

equipment intended for use in other places liable to be endangered by explosive 

atmospheres. The categories of equipment correspond to the required levels of protection. 

Table 1 lists the levels of protection for Group II equipment (i.e. for use in atmospheres other 

than mines).

Table 1: Levels of Protection

Category 

(Group II)

Level of 

protection

Performance of protection Conditions of operation 

(gases)

1 Very high Two independent means of 

protection or safe even when two 

faults occur independently of 

each other.

Equipment remains 

energized and functioning 

in Zones 0,1,2

2 High Suitable for normal operation and 

frequently occurring disturbances 

or equipment where faults are 

normally taken into account 

Equipment remains 

energized and functioning 

in Zones 1, 2 

3 Normal Suitable for normal operation Equipment remains 

energized and functioning 

in Zone 2.
Application to RAC equipment

Annex I of the directive defines the equipment groups and categories according to the 

characteristics of the equipment in question. Most refrigeration and air conditioning equipment 

corresponds to Equipment-group II, category 3:

Comprises equipment designed to be capable of functioning in conformity with the 

operating parameters established by the manufacturer and ensuring a “normal” level 

of protection. Equipment in this category is intended for use in areas in which 

explosive atmospheres caused by gases, vapours, mists, or air/dust mixtures are 

unlikely to occur or, if they do occur, are likely to do so only infrequently and for a short 

period only. Equipment in this category ensures the requisite level of protection during 

normal operation. Equipment in this category must comply with the supplementary 

requirements referred to in Annex II, 2.3.

There is no clear quantitative division for when equipment falls under the scope, and therefore 

requires application of ATEX. Therefore, it is ultimately the responsibility of the manufacturer 

to determine whether the equipment in question corresponds with the scope. All refrigeration 

equipment containing flammable refrigerant has the potential to produce an explosive 

atmosphere. Similarly, virtually all equipment that is operated in any way by electricity or fuel 

gas will contain a potential source of ignition.

For “small” systems, a relatively clear indication is given by the Commission based on a 

certain exemption within the Directive, being “equipment intended for use in domestic and 

non-commercial environments where potentially explosive atmospheres may only rarely be 

created, solely as a result of the accidental leakage of fuel gas”. On this basis, a question 

was raised at the ATEX Standing Committee about equipment intended for use in domestic 

environments where leakages of gases are not fuel gas. It was agreed that, as a general rule, 

such types of equipment are also excluded from the Directive as they are not intended for

use in a potentially explosive atmosphere. In other words, all domestic refrigeration and air 

conditioning appliances are exempt. 

(http://europa.eu.int/comm/enterprise/atex/domesticenvironment.htm)

There is no clear cut-off criteria within the scope, such as amount of flammable material, 

probability of explosion, or magnitude of consequences. It is not easy to determine whether 

“medium” or “large” systems fall within ATEX. A further question was put to the Commission 
regarding the remaining equipment, but responded that each should be considered on a 

case-by-case basis (CEN TC 182 WG6 N074).

In general, consideration of the likelihood and duration of an explosive atmosphere occurring 

is required to determine the equipment group. For the given equipment group, requirements 

of the equipment category are then considered. If it is possible to prove that potential sources 

of ignition are not present under the definitions for that equipment category, then the 

equipment does not fall under the Directive. 

For equipment Group II, potential ignition sources are defined as sparks, flames, electric 

arcs, high surface temperatures, acoustic energy, optical radiation, electromagnetic waves, 

etc. This includes static electricity, stray electric and leakage currents and overheating. 

These requirements are limited for equipment in category 3 in that equipment must be so 

designed and constructed as to prevent foreseeable ignition sources, which can occur during 

normal operation. Surface temperatures must not exceed the stated maximum surface 

temperatures under intended operating conditions. Higher temperatures in exceptional 

circumstances may be allowed only if the manufacturer adopts special additional protective 

measures.

Thus, if there are no potential sources of ignition during normal operation, then the equipment 

does not fall under the Directive. This can be demonstrated by reference to pr EN 378: 2005. 

Clause 6.2.13 Protection against explosion hazards, of Part 2 states:

Equipment within the scope of EN 60335-2-40, EN 60335-2-24 or EN 60335-2-89 shall 

comply with the requirements of these standards.

Other refrigeration systems using A2, A3, B2 or B3 refrigerants shall be constructed 

so that any leaked refrigerant will not flow or stagnate so as to cause a fire or 

explosion hazard in areas within the system 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. This clause is not applicable for R717refrigerating 

systems.

Separate components, such as thermostats, which are charged with less than 0.5 g 

of a flammable gas are not considered to cause a fire or explosion hazard in the event 

of leakage of the gas within the component itself.

All electrical components shall comply with one of the following:

• IEC 60079-15 sections 3 and 4 for group IIA gases or the refrigerant used;
• Not located in an area where a potentially flammable gas mixture will 

accumulate as demonstrated by the leakage test as described in Annex D;

• be located in an enclosure. The enclosure containing the electrical 

components shall comply with IEC 60079-15 for enclosures suitable for use 

with group IIA gases or the refrigerant used.

NOTE For The test current of a component the test of a switching component the 

rated current of the component or the actual load controlled shall be used.

Appendix 1 details Annex F of prEN 378: 2003 Part 2.

Compliance

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

Requirements (ESRs) is required as detailed in Appendix 2, and summarised in Fig. 1. This is 

achieved through conformity to a Module of production criteria as specified in Article 8 of the 

Directive, which requires:

The manufacturer or his authorized representative established in the Community 

must, in order to affix the CE marking, follow the procedure relating to internal control 

of production referred to in Annex VIII.

Annex VIII defines the module “internal control of production”, and describes the procedure 

whereby the manufacturer (or his authorized representative) ensures and declares that the 

equipment satisfy the requirements of the Directive. Thus, this module only requires selfcertification. In summary, the manufacturer (or his authorized representative) shall:

− Affix the CE marking to each piece of equipment and draw up a written declaration of 

conformity.

− Establish technical documentation and he or his authorized representative shall keep 

it at the disposal of the relevant national authorities for inspection purposes for a 

period ending at least 10 years after the last piece of equipment was manufactured. 

Ensure technical documentation enables the conformity of the equipment with the 

relevant requirements of the Directive to be assessed. It shall cover the design, 

manufacture and operation of the product and contain a description of the equipment, 

conceptual design and manufacturing drawings with descriptions and explanations 

including for the operation of the equipment, a list of the standards applied and 
descriptions of how the safety aspects where standards have not been applied, 

results of design calculations and examinations, and test reports.

− Keep a copy of the declaration of conformity with the technical documentation.

− Take all measures necessary to ensure that the manufacturing process guarantees 

compliance of the manufactured equipment with the technical documentation.

Alternatively, any other module that specifies stricter requirements may be used, most of 

which require third-party involvement.

Appendix 1: extract from pr EN 378-2: 2005

Evaluate magnitude of

consequence in the event of

ignition

Check conformity to

requirements of appropriate

standards

estimate level of risk

consider improving design -

minimise charge, safety

systems/detection, dispersion

techniques, leak avoidance

apply marking for conformity,

warnings and guidance

write instructions for use and

maintenance of equipment

Evaluate liklihood of

development of a flammable

atmosphere, considering

faults and misuse of

equipment

Consider sources of ignition

associated with the equipment

Fig. 0: Flow chart for meeting ESR’s
Annex D: Requirements according to 6.2.13 for refrigerating systems and heat pumps using 

flammable refrigerants

D.1 Leakage Tests

Where flammable refrigerants are employed it is necessary to test electrical components to 

determine whether they are a source of ignition. The Following test is applied on one sample 

of each refrigeration system containing A2, A3, B2 or B3 refrigerants, except for R717, as

indicated in clause 6.2.13 of this standard. 

A leakage of refrigerant is simulated at the most critical point in the refrigeration system. The 

method to simulate a leakage at the most critical point is to inject refrigerant vapour through a 

suitable capillary tube at that point. A critical point is a joint in the refrigerant system tubing, a 

bend of more than 90°, or other point judged to be a weak point in the refrigerant containing 

system due to the thickness of the metal, exposure to damage, sharpness of a bend or the 

manufacturing process. A quantity of refrigerant leaked is equal to the rated charge amount or 

the amount that will leak as determined by test. The refrigerant is injected at the most critical 

point and the most unfavourable direction at ambient temperature (20 °C to 25 °C).

The refrigerant charge that can leak is determined by the maximum refrigerant charge. The 

product is modified by placing the simulated leak hole, by releasing the full charge at a rate of 

100 g/min per 1 m3 of internal volume of the enclosure containing the electrical components, 

at the most critical point. The capillary tube is controlled to the extent that it can be fully 

opened or closed at will. The leak is made by opening the capillary tube until the maximum 

amount has leaked as determined by measurement.

During this test the refrigeration system is switched off or operated under normal operation at 

rated voltage, whichever gives the most unfavourable result unless a prepurge is activated 

prior to energizing any loads. In which case the test shall be conducted with the refrigeration 

system operating. During a test where the refrigeration system is operating, refrigerant gas 

injection is started at the same time as the refrigeration system is switched on.

The quantity of refrigerant is taken from the vapour side of a refrigerant gas bottle, which shall 

contain enough refrigerant to ensure that there will still be liquid refrigerant left in the bottle at 

the end of the test.
If a blend refrigerant is used that can fractionate, the test is carried out using the blend 

component that has the smallest value of the lower flammable limit.

The test is conducted in a room that is free of draft and of sufficient size to conduct the test.

The minimum volume of the test room ( V ) is:

LFL

4 m

V

×

=

where:

V is m3 considering a ceiling height not less than 2.2 m.

m is the refrigerant charge mass in kg.

LFL is the Lower Flammable Limit in kg/m3 as specified in Annex E of prEN 378-1:2005.

NOTE 1 The quantity of gas injected should preferably be measured by weighing the bottle.

NOTE 2 Care should be taken that the installation of the capillary tube does not unduly 

influence the results of the test and that the structure of the refrigeration system is not in a 

position to unduly influence the results of the test.

NOTE 3 The instrument used for monitoring the refrigerant gas concentration should have a 

fast response to the gas concentration, typically 2 to 3 seconds and shall be located so as to 

not unduly influence the results of the test.

NOTE 4 If gas chromatography is used to measure the refrigerant gas concentrations the gas 

sampling in confined areas shall occur at a rate not exceeding 2 ml in every 30 s. 

The measured concentration of refrigerant gas surrounding the potential source of ignition 

shall not exceed 75 % of the LFL of the refrigerant gas, and shall not exceed 50 % of the LFL 

of the refrigerant gas for a time period of 5 min or the duration of the test if less than 5 min 

during and after the amount has been injected. The measured concentration of refrigerant gas 

surrounding a component that will not function during the prepurge time may exceed the 75 % 

of the LFL during the prepurge time. The LFL for the refrigerant, as specified in Annex E of 

prEN 378-1-2005, is used.
Appendix 2: Key essential safety requirements

For most refrigeration equipment, the key essential safety requirements are summarised 

below.

Equipment intended for use in potentially explosive atmospheres must be designed from the 

point of view of integrated explosion safety. In this connection, the manufacturer must take 

measures:

− To prevent the formation of explosive atmospheres which may be produced or 

released by equipment,

− To prevent the ignition of explosive atmospheres, taking into account the nature of 

every electrical and non-electrical source of ignition,

− Should an explosion occur which could endanger persons, domestic animals or 

property, to halt it immediately and/or to limit the range of explosion flames and 

explosion pressures to a sufficient level of safety.

Equipment must be designed and manufactured after due analysis of possible operating 

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

reasonably be anticipated must be taken into account. Equipment subject to special checking 

and maintenance conditions must be designed and constructed with such conditions in mind. 

Equipment must be so designed and constructed as to be capable of coping with actual or 

foreseeable surrounding area conditions.

All equipment must be marked legibly and indelibly with: name and address of the 

manufacturer, CE marking, designation of series or type, serial number if any, year of 

construction, explosion protection marking (“Ex” symbol) and the letter 'G' (for explosive 

atmospheres caused by gases). Where necessary, they must also be marked with all 

information essential to their safe use.

All equipment must be accompanied by instructions, including at least the following:

− the information with which the equipment is marked (except serial number), together 

with any appropriate additional information to facilitate maintenance (e.g. address of 

the importer, repairer, etc)
− instructions for safe: - putting into service, - use, - assembling and dismantling, -

maintenance (servicing and emergency repair), - installation, - adjustment; - an 

indication of the danger areas in front of pressure-relief devices

− 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.

The instructions must be drawn up in one of the Community languages by the manufacturer. 

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. Literature describing the equipment must not contradict the 

instructions with regard to safety aspects.

Equipment, which may release flammable gases, must wherever possible employ enclosed 

structures. If equipment contains openings or non-tight joints, these must as far as possible 

be designed in such a way that developing gases cannot give rise to explosive atmospheres 

outside the equipment. Points where materials are introduced or drawn off must, as far as 

possible, be designed and equipped to limit escapes of flammable materials during filling or 

draining. If equipment is in a housing or a locked container forming part of the explosion 

protection itself, it must be possible to open such housing or container only with a special tool 

or by means of appropriate protection measures.