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Specialist's Manual
detergents containing chlorine shall be avoided as the chlorine may react with the
refrigerant and corrode the copper pipe-work.
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.
The following leak detection methods are deemed acceptable for all refrigerant
systems.
Electronic leak detectors may be used to detect refrigerant leaks but, in the case of
flammable refrigerants, the sensitivity may not be adequate, or may need
re-calibretion. (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
the refrigerant and shall be calibrated to the refrigerant employed, and the
appropriate percentage of gas (25% maximum) is confirmed.
Leak detection fluids are also 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.
NOTE: Examples of leak detection fluids are
- bubble method,
- fluorescent method agents.
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. Removal of refrigerant shall be according to
clause Removal and evacuation.
Removal and evacuation
When breaking into the refrigerant circuit to make repairs - or for any other purpose
- conventional procedures shall be used. However, for flammable refrigerants 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 with inert gas;
open the circuit by cutting or brazing.
The refrigerant charge shall be recovered into the correct recovery cylinders. For
appliances containing flammable refrigerants, the system shall be purged with
oxygen-free nitrogen to render the appliance safe for flammable refrigerants.
This process may need to be repeated several times. Compressed air or
oxygen shall not be used for purging refrigerant systems.
For appliances containing flammable refrigerants, refrigerants purging shall be
achieved by breaking the vacuum in the system with oxygen-free nitrogen 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
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