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33
EN
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.
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 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.
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
oxygen shall not be used for this task.
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