Toshiba MMU-UP0151SH-E Installation Manual page 11

• 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.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.
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.
19-EN
• 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 use 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) in 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.
• 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.
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20-EN