43
Installation and Maintenance
terminals 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 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
specifications.
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 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.
●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 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.
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 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 flammability is a consideration. The
following procedure shall be adhered to:
1.remove refrigerant;
2.purge the circuit with inert gas; evacuate;
3.purge again with inert gas;
4.open the circuit by cutting or brazing.
The refrigerant charge shall be recovered into the correct recovery
cylinders.
For appliances containing flammable refrigerants, 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
