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. Intrinscially 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. 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 or extinguished. If a leakage of refrigernat 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.
15. 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. Opening of the refrigerant systems shall not be done by
brazing. 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.
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