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2) Work procedure
Work shall be undertaken under a controlled procedure so as to minimize the risk of a flammable gas or vapour being
present while the work is being performed.
3) General work area
All maintenance staff and others working in the local area shall be instructed on the nature of work being carried out.
Work in confined spaces shall be avoided. The area around the workspace shall be sectioned off. Ensure that the
conditions within the area have been made safe by control of flammable material.
4)Checking for presence of refrigerant
The area shall be checked with an appropriate refrigerant detector prior to and during work, to ensure the technician is
aware of potentially flammable atmospheres. Ensure that the leak detection equipment being used is suitable for use
with flammable refrigerants, i.e. non-sparking, adequately sealed or intrinsically safe.
5)Presence of fire extinguisher
If any hot work is to be conducted on the refrigeration equipment or any associated parts, appropriate fire
extinguishing equipment shall be available to hand. Have a dry powder or CO2 fire extinguisher adjacent to the
charging area.
6) No ignition sources
No person carrying out work in relation to a refrigeration system which involves exposing any pipe work that contains
or has contained flammable refrigerant 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 kept sufficiently far away from
the site of installation, repairing, removing and disposal, during which flammable refrigerant can possibly be released
to the surrounding space. Prior to work taking place, the area around the equipment is to be surveyed to make sure
that there are no flammable hazards or ignition risks. No Smoking signs shall be displayed.
7) Ventilated area
Ensure that the area is in the open or that it is adequately ventilated before breaking into the system or conducting any
hot work. A degree of ventilation shall continue during the period that the work is carried out. The ventilation should
safely disperse any released refrigerant and preferably expel it externally into the atmosphere.
7 Cabling
Check that cabling will not be subject to wear, corrosion, excessive pressure, vibration, sharp edges or any other
adverse environmental effects. The check shall also take into account the effects of aging or continual vibration from
sources such as compressors or fans.
8 Detection of flammable refrigerants
Under no circumstances shall potential sources of ignition be used in the searching for or detection of refrigerant leaks.
A halide torch (or any other detector using a naked flame) shall not be used.
9 Leak detection methods
The following leak detection methods are deemed acceptable for systems containing flammable refrigerants.
Electronic leak detectors shall be used to detect flammable refrigerants, but the sensitivity may not be adequate, or
may need re-calibration.
(Detection equipment shall be calibrated in a refrigerant-free area.) Ensure that the detector is not a potential source of
ignition and is suitable for the refrigerant used.
Leak detection equipment shall be set at a percentage of the LFL of the refrigerant and shall be calibrated to the
refrigerant employed and the appropriate percentage of gas (25% maximum) is confirmed. Leak detection fluids are
suitable for use with most refrigerants but the use of detergents containing chlorine shall be avoided as the chlorine
may react with the refrigerant and corrode the copper pipe-work. If a leak is suspected, all naked flames shall be
removed/ extinguished.
If a leakage of refrigerant is found which requires brazing, all of the refrigerant shall be recovered from the system, or
isolated (by means of shut off valves) in a part of the system remote from the leak.
Oxygen free nitrogen (OFN) shall then be purged through the system both before and during the brazing process.
10 Removal and evacuation
When breaking into the refrigerant circuit to make repairs or for any other purpose conventional procedures shall be
used. However, it is important that best practice is followed since flammability is a consideration. The following
procedure shall be adhered to:
Remove refrigerant; Purge the circuit with inert gas; Evacuate; Purge again with inert gas; Open the circuit by cutting or
brazing.
The refrigerant charge shall be recovered into the correct recovery cylinders. The system shall be flushed with OFN to
render the unit safe. This process may need to be repeated several times. Compressed air or oxygen shall not be used
for this task. Flushing shall be 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 shall be
repeated until no refrigerant is within the system. When the final OFN charge is used, the system shall be vented down
to atmospheric pressure to enable work to take place. This operation is absolutely vital if brazing operations on the
pipe-work are to take place. Ensure that the outlet for the vacuum pump is not close to any ignition sources and there is
ventilation available.
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