compressors or fans.
5. Detecn of ammable refrigerants
Under no circumstances shall potenal sources of ignin be used in the searching for or deteon of refrigerant leaks. A
halide torch (or any other detector using a nakedame) shall not be used.
6. Leak detecn methods
The following leak deteon methods are deemed acceptable for systems containing ammable refrigerants.
Electronic leak detectors shall be used to detect mable refri
gerants, but the sensvity may not be adequate, or may
need re-calibraon. (Deteon equipment shall be calibrated in a refrigerant-free area.) Ensure that the detector is not a
potenal source of ignon and is suitable for the refrigerant used. Leak deteon 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 conrmed.
Leak deteon uids 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 nakedes shall be removed/ exnguished.
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 o valves) in a part of the sys
tem 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 evacua
When breaking into the refrigerant circuit to make repairs – or for any other purpose –convenonal procedures shall be used.
However, it is important that best prace is followed sincemability is a consideraon. The following procedure shall be
adhered to:
1) Remove refrigerant.
2) Purge th
e circuit with inert gas.
3) Evacuate.
4) Purge again with inert gas.
5) Open the circuit by cung or brazing.
The refrigerant charge shall be recovered into the correct recovery cylinders. The system shall be “ushed” with OFN to render
the unit safe. This process may need to be repeated several es. 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 connuing to l un the work
ing pressure is
achieved, then venng to atmosphere, and nally pulling down to a vacuum. This process shall be repeated un no
refrigerant is within the system. When the nal OFN charge is used, the system shall be vented down to atmospheric pressure
to enable work to take place. This operaon is absolutely vital if brazing operaons on the pipe-work are to take place.
Ensure that the outlet for the vacuum pump is not close to any ign
on sources and there is venaon available.
8. Charging procedures
In addon to convenonal charging procedures, the following requirements shall be followed.
1) Ensure that contaminaon of dierent refrigerants does not occur when using charging equipment. Hoses or lines shall be as
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