Toshiba MCY-MUG0401HSW-E Service Manual page 21

- That capacitors are discharged to avoid possibility of sparking.
- That there no live electrical components and wiring are exposed while charging, recovering or
- purging the system.
- That there is continuity of earth bonding.
10. Repairs to sealed components
• During repairs to sealed components, all electrical supplies shall be disconnected from the equipment being
worked upon prior to any removal of sealed covers, etc.
• If it is absolutely necessary to have an electrical supply to equipment during servicing, then a permanently
operating form of leak detection shall be located at the most critical point to warn of a potentially hazardous
situation.
• Particular attention shall be paid to the following to ensure that by working on electrical components, the casing
is not altered in such a way that the level of protection is affected.
• This shall include damage to cables, excessive number of connections, terminals not made to original
specification, damage to seals, incorrect fitting of glands, etc.
• Ensure that apparatus is mounted securely.
• Ensure that seals or sealing materials have not degraded to the point that they no longer serve the purpose of
preventing the ingress of flammable atmospheres.
• Replacement parts shall be in accordance with the manufacturer's specifications.
NOTE
The use of silicon sealant may inhibit the effectiveness of some types of leak detection equipment.
Intrinsically safe components do not have to be isolated prior to working on them.
11. Repairs 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.
12. Cabling
• Check that cabling will not be subject to wear, corrosion, excessive pressure, vibration, sharp edges or any other
adverse environmental effects.
• Check shall also take into account the effects of aging or continual vibration from sources such as compressors
or fans.
13. 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.
• Electronic leak detectors may be used to detect refrigerant leaks but, in the case of flammable refrigerants, 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 also suitable for use with most refrigerants but the used of detergents containing chlorine
shall be avoided as the chlorine may react with the refrigerant and corrode containing chlorine.
• 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) is a part of the system remote from the leak.
14. Leak detection methods
• Electronic leak detectors shall be used to detect flammable refrigerants leak, 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.
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