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10. 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.
11. Leak detection methods
The following leak detection methods are deemed acceptable for
systems containing flammable refrigerants. Electronic leak detec-
tors shall be used to detect flammable refrigerants, but the sensi-
tivity may not be adequate, or may need re-calibration. (Detec-
tion equipment shall be calibrated in a refrigerant-free area.) En-
sure 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 per-
centage 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 cop-
per pipe-work. If a leak is suspected, all naked flames shall be re-
moved/ 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.
12. Removal and evacuation
When breaking into the refrigerant circuit to make repairs or for
any other purpose conventional procedures shall be used. How-
ever, it is important that best practice is followed since flammabil-
ity 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 recov-
ery 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