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Safety guidelines for venting Hydrocarbon Refrigerants

1. Introduction

There is an ongoing discussion over whether hydrocarbon (HC) refrigerants can be vented or 

recovered. The objective of this document is not to address the legal position or the 

environmental issues of venting. Since forthcoming legislation – such as the WEEE directive 

– permits venting of hydrocarbon refrigerants under certain circumstances, it is necessary to 

provide guidance on how to vent HC refrigerants.

Note that the “work area” refers to both the area inside, where the equipment is located, and 

also the area outside, where the HC is to be vented.

2. Practical competence

Any person who is involved with working on or breaking into a refrigerant circuit should hold a 

current valid certificate from an industry accredited assessment authority, which authorises 

their competence to handle refrigerants (including hydrocarbons) safely in accordance with 

an industry recognised assessment specification.

Servicing shall only be performed as recommended by the equipment manufacturer. 

Maintenance and repair requiring the assistance of other skilled personnel shall be carried out 

under the supervision of the person competent in the use of flammable refrigerants. 

Refer to the draft European Standard EN 13313.

3. General approach to hydrocarbon refrigerant handling

All flammable refrigerant gases when mixed with air form a flammable mixture. The effect of 

ignition of such a mixture can be severe. It is therefore important that the appropriate safety 

requirements are observed at all times when working with flammable refrigerants. 

If the installation permits, it is recommended that the equipment be removed from its existing 

position to a controlled workshop environment suitable for the type of repair where work can 

be conducted safely. Work shall be undertaken under a controlled procedure so as to 

minimise the risk of a flammable gas or vapour being present while the work is being 

performed.
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Refrigerant will remain in oil. Use of recovery machine/vacuum machine accelerates

desorption of refrigerant from oil. Immediately after venting refrigerant there may be as much 

as 10 % refrigerant left in the oil. 

4. Safety checks

Prior to beginning work with HCs, safety checks are necessary to ensure that the risk of 

ignition is minimised. The following precautions shall be complied with.

General work area

All maintenance staff and others working in the local area should be instructed as to 

the nature of work being carried out. Work in confined spaces must be avoided. The 

area around the workspace is to be sectioned off, as far as is practicable. 

Presence of fire extinguisher

Appropriate fire extinguishing equipment shall be available to hand. Have a dry powder 

or CO2 fire extinguisher adjacent to the area. 

No ignition sources

No person shall use any sources of ignition in such a manner that it may lead to the 

risk of fire or explosion. All possible ignition sources, including cigarette smoking, 

should be sufficiently far away from the site of installation, repairing, removing and 

disposal during which flammable refrigerant can possibly be released to surrounding 

space. Prior to work taking place, the area around the equipment is to be surveyed to 

establish any flammable hazards or ignition risks. Display 'No Smoking' signs. 

Ventilated area

Ensure that the area is in the open or that it is adequately ventilated before breaking 

into the system. A degree of ventilation should continue during the period that the 

venting is carried out, and should be adequate to disperse any released refrigerant.

Refrigerant detection

Under no circumstances should potential sources of ignition be used in the searching 

or detection of refrigerant. A halide torch (or any other detector using a naked flame) 

must not be used. Electronic leak detectors may be used to detect hydrocarbons. 
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5. Breaking into a system

When breaking into the refrigerant circuit to vent refrigerant slowly, one of the following 

procedures shall be used:

− Use recovery machine to draw out, and discharge refrigerant into hose,

− Connect hose to a schraeder valve,

− Use a piercing valve, connected to a hose.

When not using a recovery machine, it may be possible to purge the circuit with inert gas. 

This will help dilute the refrigerant prior to discharging, and will assist in removing residual 

amounts of refrigerant around the system. On no account use compressed air or oxygen for 

this task. If it is necessary to warm the system/compressor, use only warm water or air, not 

naked flames or radiant heaters, the temperature of the water or air must not exceed 40°C

Flushing is achieved by breaking the vacuum in the system with OFN and continuing to fill 

until the working pressure is achieved, then venting to atmosphere, and finally pulling down to 

a vacuum. This process is repeated until satisfied that no hydrocarbons are within the 

system. When the final OFN charge is used, the system can be vented down to atmospheric 

pressure to enable work to take place. This operation is absolutely vital if brazing operations 

on the pipework are to take place Ensure that the outlet for the vacuum pump is not close to 

any ignition sources and there is ventilation available.

6. Considerations for venting

The following considerations are critical to the act of venting the refrigerant. They shall be 

adhered to in order to vent safety.

− Venting small amounts of hydrovarbon at low rates is permissible provided that a risk 

assessment is undertaken, site procedures are followed, and appropriate permits to 

work are issued.

− Venting shall only be done to the outside. Venting into a confined, or partially confined 

space is not acceptable.

− Use as long a hose as possible. The minimum length should enable the technician to 

discharge at least 2 m away from the building.

− Display flammable gas hazard warning signs near to the point of discharge.

− The state of the refrigerant has little effect on the safety of venting.
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− Vent at a rate as low as possible – the refrigerant will disperse more readily. This can 

be helped by use of a metering valve.

− Venting should only be made from a position above ground level, and should not be 

allowed to travel towards a position that is below ground level, such as troughs, 

drains, or basements. 

− Ensure that the refrigerant is discharged to a point where the air is not still. A higher 

wind speed will improve dispersion of the release. 

BOC Refrigerants, Guildford May 2005.