9
Safety
Precautions
Page 9
8.
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.
9.
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.
10.
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.
11.
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.
12.
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
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.
2)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 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.
