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WARNING
(For using R290/R32 refrigerant only)
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, should 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) should 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 should 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 should 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 pipework.
• If a leak is suspected, all naked flames should be removed/ extinguished. If a leakage of refrigerant is
found which requires brazing, all of the refrigerant should 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) should
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, it is important that best practice is followed since flammability is a consideration.
Opening of the refrigeration systems should 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.
• The refrigerant charge should be recovered into the correct recovery cylinders. The system should
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.
• Flushing should be achieved by breaking the vacuum in the system with OFN and continuing to fill until
the working pressure is achieved, then venting to atmosphere, and finally pulling down to a vacuum. This
process shall be repeated until no refrigerant is within the system.
• When the final OFN charge is used, the system shall be vented down to atmospheric pressure to enable work
to take place. This operation is absolutely vital if brazing operations on the pipework are to take place.
• Ensure that the outlet for the vacuum pump is not close to any ignition sources and there is ventilation
available.
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