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 (Annex DD.6)
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 (Annex DD.7)
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 (Annex DD.8)
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 (Annex DD.9)
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 oxygen shall not be used for this task.
English
• 35
