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5.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.
6.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.
7.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
