84
Installation and Maintenance
Service Manual
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:
— that capacitors are discharged: this shall be done in a
safe manner to avoid possibility of sparking;
— that no live electrical components and wiring are exposed
while charging, recovering or purging the system;
— that there is continuity of earth bonding.
● 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 tting of glands, etc.
— Ensure that the 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 specications.
NOTE: The use of silicon sealant can inhibit the effectiveness
of some types of leak detection equipment. Intrinsically safe
components do not have to be isolated prior to working on
them.
● 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.
● Cabling
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.
● Detection of ammable 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 ame) shall
not be used.
● Leak detection methods
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 recalibration.
(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 conrmed.
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 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. For appliances containing flammable
refrigerants, oxygen free nitrogen (OFN) shall then be purged
through the system both before and during the brazing
process.
● Removal and evacuation
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 is followed since ammability is
a consideration. The following procedure shall be adhered to:
● remove refrigerant;
● purge the circuit with inert gas;
● evacuate;
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