Midea MWMW050CM1A Manuel Du Propriétaire page 10

9. 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.
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.
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.
Removal of refrigerant shall be according to Removal and evacuation.
11.Removal and evacuation
When breaking into the refrigerant circuit to make repairs—or for any other purpose
- conventional procedures shall be used. However, for flammable refrigerants it is
important that best practice be followed, since flammability is a consideration.
The following procedure shall be adhered to:
-Safely remove refrigerant following local and national regulations;
-Evacuate;
-Purge the circuit with inert gas (optional for A2L);
-Evacuate (optional for A2L);
-continuously flush or purge with inert gas when using flame to open circuit; and
-open the circuit.
The refrigerant charge shall be recovered into the correct recovery cylinders if
venting is not allowed by local and national codes. For appliances containing
flammable refrigerants, the system shall be purged with oxygen-free n flammable
refrigerants. This process might compressed air or oxygen shall not be used for
purging refrigerant systems.
For appliances containing flammable refrigerants, refrigerants purging shall be
achieved by breaking the vacuum in the system with oxygen-free nitrogen and
continuing to fill until the working pressure is achieved, then venting to atmosphere,
and finally pulling down to a vacuum (optional for A2L). This process shall be
repeated until no refrigerant is within the system (optional for A2L). When the final
oxygen-free nitrogen charge is used. the system shall be vented down to
atmospheric pressure to enable work to take place. The outlet for the vacuum
pump shall not be close to any potential ignition sources, and ventilation shall
be available.
12.Charging procedures
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 lines shall be as short as possible to minimise
the amount of refrigerant contained in them. Cylinders shall be kept in an appropriate
position according to the instructions. Ensure that the refrigeration system is earthed
prior to charging the system with refrigerant. Label the system when charging is
complete (if not already). Extreme care shall be taken not to overfill the refrigeration
system. Prior to recharging the system it shall be pressure tested with OFN. The
system shall be leak tested on completion of charging but prior to commissioning.
A follow up leak test shall be carried out prior to leaving the site.
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