Mitsubishi Electric PUZ-WZ50VAA Manual page 7

1. Safety precautions
• 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, termi-
nals not made to original specification, damage to
seals, incorrect fitting of glands, etc.
Ensure that the apparatus is mounted securely.
Ensure that seals or sealing materials have not de-
graded to the point that they no longer serve the
purpose of preventing the ingress of flammable at-
mospheres.
Replacement parts shall be in accordance with the
manufacturer's specifications.
• Do not apply any permanent inductive or capaci-
tance 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 igni-
tion of refrigerant in the atmosphere from a leak.
• Check that cabling will not be subject to wear, cor-
rosion, 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 pumps.
• 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 re-
frigerant leaks but, in the case of flammable refrig-
erants, 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 per-
centage 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 re-
moved/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.
For appliances containing flammable refrigerants,
oxygen free nitrogen (OFN) shall then be purged
through the system both before and during the
brazing process.
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