Specialist’s Manual
25
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that capacitors are discharged: this shall be
that there is continuity of earth bonding.
resistant to being corroded or are suitably protect-
ed against being so corroded.
– that no live electrical components and wiring are
done in a safe manner to avoid possibility of
sparking;
exposed while charging, recovering or purging the
system;
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Repair to intrinsically safe components
Repairs to sealed components
Sealed electrical components shall be replaced.
Intrinsically safe components must be replaced.
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Cabling
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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.
Checks to electrical devices
Repair and maintenance to electrical components
shall include initial safety checks and component
inspection procedures. If a fault exists that could
compromise safety, then no electrical supply shall
be connected to the circuit until it is satisfactorily
dealt with. If the fault cannot be corrected immedi-
ately but it is necessary to continue operation, an
adequate temporary solution shall be used. This
shall be reported to the owner of the equipment so
all parties are advised.
Initial safety checks shall include:
– bubble method,
– fluorescent method agents.
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Removal and evacuation
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.
The following leak detection methods are deemed
acceptable for all refrigerant systems.
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.
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. Removal of refrigerant shall be according to
clause Remov
al and evacuation.
Leak detection fluids are also suitable for use with
most refrigerants but the use of detergents con-
taining chlorine shall be avoided as the chlorine
may react with the refrigerant and corrode the
copper pipe-work.
NOTE: Examples of leak detection fluids are
– safely remove refrigerant following local and
national regulations;
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evacuate;
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purge the circuit with inert gas (optional for A2L);
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evacuate (optional for A2L);
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continuously flush or purge with inert gas when
using flame to open circuit; and
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open the circuit.
When breaking into the refrigerant circuit to make
repairs – or for any other purpose –conventional
procedures shall be used. However, for flammable
refrigerants it is important that best practice be
followed, since flammability is a consideration.
The following procedure shall be adhered to:
The refrigerant charge shall be recovered into the
correct recovery cylinders if venting is not allowed
by local and national codes. For appliances con-
taining flammable refrigerants, the system shall be
purged with oxygen-free nitrogen to render the
appliance safe for flammable refrigerants. This
process might need to be repeated several times.
Compressed air or oxygen shall not be used for
purging refrigerant systems.
For appliances containing flammable refrigerants,
refrigerants purging shall be achieved by breaking
the vacuum in the system with oxygen-free nitro-
gen and continuing to fill until the working pres-
sure is achieved, then venting to atmosphere, and
finally pulling down to a vacuum (optional for A2L).
This process shall be repeated until no refrigerant
is within the system (optional for A2L). When the
final oxygen-free nitrogen charge is used, the
system shall be vented down to atmospheric pres-
sure to enable work to take place.
The outlet for the vacuum pump shall not be close
to any potential ignition sources, and ventilation
shall be available.
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