Hitachi RAI-50PPD Manuel D'installation Et De Fonctionnement page 14

IMPORTANT NOTICE
or explosion, including cigarette smoking, must be kept
sufficiently far away from the working area, since refrigerant
may be released to the surrounding space. The area around
the equipment shall be checked before beginning the work
to make sure there is no risk of ignition or fire hazard. "No
Smoking" signs shall be displayed.
• The area must be adequately ventilated before beginning the
work, and a degree of ventilation must be ensured while the
work is being carried out. Ventilation should safely disperse
any released refrigerant and preferably expel it externally
into the atmosphere.
• Repair and maintenance of electrical components shall
include initial safety checks and component inspection
procedures. If a fault compromises safety, then the circuit
shall not be connected to the power supply until the fault has
been solved satisfactorily. If the fault cannot be addressed
immediately, but it is necessary to resume operation, an
adequate temporary solution shall be applied. This shall be
reported to the owner of the equipment so all parties are
advised. Initial safety checks shall include:
- Capacitor discharge: This shall be done in a safe manner
to avoid sparks
- Exposure of live electrical components and wiring while
the system is being charged, recovered or purged
- Continuity of earth bonding
• During repair works, all the power supply connections must
be disconnected from the equipment before removing any
part such as a sealed cover. If it is absolutely necessary to
keep the power supply of the 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 not to alter the casing when
working on electrical components, in such a way that the
level of protection is affected. This includes the damage
to cables and seals, incorrect fitting of glands, terminals
not made to original specification, excessive number of
connections, etc. The unit shall be mounted securely, and
the seals or sealing materials must not have been degraded
such that they no longer serve the purpose of preventing the
ingress of flammable atmospheres. Replacement parts shall
be in accordance with the manufacturer specifications.
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N O T E
The use of silicon sealant may inhibit the effectiveness of some types of
leak detection equipment.
• Do not apply any permanent inductive or capacitive load
to the circuit without first making sure that this will not
exceed the permissible voltage and current permitted for the
equipment in use.
Intrinsically safe components do not have to be isolated
before working on them. They are the only type which can
be worked on while live in the presence of a flammable
atmosphere. The test apparatus shall be at the correct
rating.
Check that wiring is not subject to wear, corrosion, excessive
pressure, vibration, sharp edges or any other cause of
4 PMML0477 rev.2 - 11/2017
damage. The check shall also take into account the effect
of ageing or continual vibration from sources such as
compressors of fans.
• Electronic leak detectors shall be used to detect flammable
refrigerants, but the sensitivity may not be adequate, or may
need recalibration. (Detection equipment shall be calibrated
in a refrigerant-free area)
Under no circumstance shall potential sources of ignition be
used for searching or detecting refrigerant leaks. A halide
torch (or any other detector using a naked flame) shall not
be used.
It must be ensured that the detector is not a potential source
of ignition while being suitable for the refrigerant used. Leak
detection equipment shall be set to a percentage of the LFL
(0.307 kg/m3) of the refrigerant and shall be calibrated to the
refrigerant employed and the appropriate percentage of gas
to confirm (25% maximum).
The use of leak detection fluids like detergents containing
chlorine shall be avoided as the chlorine may react with the
refrigerant and corrode the copper pipework.
• If a leak is suspected, all the naked flames shall be
extinguished. If a leakage of refrigerant is found which
requires brazing, the refrigerant shall be either entirely
recovered from the system, or isolated in a part of the
system remote from the leak by means of shut off valves.
Oxygen-free nitrogen (OFN) shall then be purged through
the system, both before and during the brazing process.
• The procedure below shall be followed when breaking
into the refrigerant circuit to make repairs or for any other
purpose:
- 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
Oxygen free nitrogen (OFN) to render the unit safe.
This process may need to be repeated several times.
Compressed air or oxygen shall not be used for this task.
Flushing shall be achieved by breaking the vacuum in the
system with OFN and continuing to fill until the working
pressure is achieved, then venting to atmosphere, and
finally pulling down to a vacuum. This process shall be
repeated until no refrigerant is within the system. When the
final OFN charge is used, the system shall be vented down
to atmospheric pressure to enable work to take place. This
operation is absolutely vital if brazing operations on the
pipework are to take place.
Ensure that the outlet for the vacuum pump is not close to
any ignition sources and there is ventilation available.
• 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