mundoclima MH-20-V9 Manuel D'installation Et L'utilisauter page 26

Cabling
9.
Check that cabling will not be subjected to wear, corrosion, excessive pressure, vibration, sharp edges
or any other adverse environmental effects. It should also be taken into account the aging effects or
continuous vibration from sources such as compressors or fans.
Detection of flammable refrigerants
10.
Under no circumstances should potential sources of ignition be used in the searching for or detection
of refrigerant leaks. A halide torch (or any other detector with a naked flame) should not be used.
Leak detection methods
11.
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 equipments should be
calibrated in a refrigerant-free area.) Ensure that the detector is not a potential source of ignition and
that it is suitable for the refrigerant in use. Leak detection equipment should be set at a percentage of
the refrigerant's LFL and should also be calibrated for the refrigerant employed and the appropriate
percentage of gas (25 % maximum) confirmed. Leak detection fluids are suitable to 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 refrigerant leak requiring brazing is found, 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.
Removal and evacuation
12.
When breaking into the refrigerant circuit to make repairs – or for any other purpose –conventional
procedures can be used. However, it is important that best practices are followed since the risk of fire
is a possibility. The following procedure should be followed:
Remove refrigerant; Purge the circuit with inert gas; Evacuate; Purge again with inert gas; Open the circuit
by cutting or brazing.
The refrigerant load should be recovered into the correct recovery cylinders. The system should also
be "flushed" with OFN to render the unit safe. This process may need to be repeated several times.
Compressed air or oxygen should 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 the atmosphere, and finally pulling down to a vacuum. This process shall be repeated until
no refrigerant is in the system. When the final OFN load is used, the system should be vented down to
atmospheric pressure so that work can take place. This operation is absolutely vital if brazing
operations on the pipe-work are needed. Ensure that the outlet for the vacuum pump is not close to
any ignition source and that there is plenty of ventilation available.
Charging procedures
13.
In addition to conventional charging procedures, the following requirements shall be followed. Ensure
that contamination of different refrigerants does not occur when using charging equipment. Hoses or
pipes should be as short as possible to minimize the amount of refrigerant in them.
Cylinders shall be kept upright.
Ensure that the refrigeration system is earthed prior to loading the system with refrigerant. Label the
system when charging is complete (if not already).
Be extra careful to not overfill the refrigeration system. Prior to recharging the system, it should be
pressure tested with OFN. The system has to be leak tested when loading is complete but prior to
being turned on. A follow up leak test has to be carried out before leaving the site.
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