Hisense AS-09TR4RMEDJ00 Service Manual page 8

8. Repair to intrinsically safe components
Do not apply any permanent inductive or capacitance loads to the circuit without ensuring that
this will not exceed the permissible voltage and current permitted for the equipment in use.
Intrinsically safe components are the only types that can be worked on while live in the
presence of a flammable atmosphere. The test apparatus shall be at the correct rating.
Replace components only with parts specified by the manufacturer.
Other parts may result in the ignition of refrigerant in the atmosphere from a leak.
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.
11.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. (Detectionequipment 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.
12.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 flammability 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.
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