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10. 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 shali 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 fitting of glands, etc.
• Ensure that apparatus is mounted securely.
• 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 silicone 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.
11. 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.
12. 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.
13. 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.
14. Leak detection methods
The following leak detection methods are deemed acceptable for systems containing flammable
refrigerants. Electronic leak detectors shall be used to detect flammable refrigerants, but
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. Oxygen free nitrogen
(OFN) shall then be purged through the system both before and during the brazing process.
