Loading ...
Loading ...
Loading ...
19. 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.
20. 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.
21. 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.
22. 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
inflammability 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 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
OFN charge is used, the system shall be vented down to atmospheric pressure to enable work to
take place. This operation is absolutely vital if brazing operations on the pipe-work are to take
place.
Ensure that the outlet for the vacuum pump is not close to any ignition sources and there is
ventilation available.
23. Decommissioning
Before carrying out this procedure, it is essential that the technician is completely familiar with
the equipment and all its detail. It is recommended good practice that all refrigerants are
recovered safely. Prior to the task being carried out, an oil and refrigerant sample shall be taken
in case analysis is required prior to re-use of reclaimed refrigerant. It is essential that electrical
power is available before the task is commenced.
INSTRUCTION FOR SERVICING(R32)
17
Loading ...
Loading ...
Loading ...