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atmosphere. The test apparatus shall be at the correct rating.
Replace components only with parts specified by the manufacturer. Other parts may result in the
ignition of refrigerant in the atmosphere from a leak.
NOTE The use of silicon sealant can inhibit the effectiveness of some types of leak detection
equipment.
Intrinsically safe components do not have to be isolated prior to working on them.
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.
Detection of flammable refrigerants
Under no circumstances shall potentially 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.
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.
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:
① remove refrigerant;
② purge the circuit with inert gas;
③ evacuate;
④ purge again with inert gas;
⑤ 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.
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