HOMCOM 821-036V70 Manual page 13

Ensure that seals or sealing materials have not 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'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.
10.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 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 manufacturer. Other parts may
result in the ignition of refrigerant in the atmosphere from a leak.
11.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.
12.Leakage detection for 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.
13.Leak detection methods
The following leak detection methods are acceptable for systems containing
flammable refrigerant.
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.) Ensure that detector is not a potential
source of ignition and is suitable for the refrigerant used.
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 leak of refrigerant is found which requires brazing, all of the refrigerant shall be
recovered from the system. Oxygen free nitrogen (OFN) shall then be purged
through the system both before and during the brazing process.
14.Removal and evacuation
When breaking into the refrigerant circuit to make repairs-or for any other purpose-
conventional procedures shall be used. However, it is important that best practice
is followed since Flammability is a consideration. The following procedure shall be
adhered to:
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 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.
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