7
Repair of 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.
Wiring
•
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.
Detection of flammable refrigerant
•
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.
•
The following leak detection methods are deemed acceptable for all refrigerant systems.
•
Electronic leak detectors may be used to detect refrigerant leaks but, in the ease of flammable refrigerants,
the sensitivity may not be adequate, or may need re-calibration. (Detection equipment shall be calibrated
in a refrigerant-tree 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 also 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 names 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.
Removal and discharge
•
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. The following procedure shall be adhered to:
-
remove refrigerant;
-
purge the circuit with inert gas (optional for A2L);
-
evacuate (optional for A2L);
-
purge with inert gas (optional for A2L);
-
open the circuit by cutting or brazing.
•
The refrigerant charge shall be recovered into the correct recovery cylinders. For appliances
containing
flammable refrigerants other than A2L refrigerants, the system shall be purged with oxygen-free nitrogen
to render the appliance safe for flammable refrigerants. This process may need to be repeated several times.
Compressed air or oxygen shall not be used for purging refrigerant systems.
Loading procedures
• Ensure that the outlet tor the vacuum pump is not close to any potential ignition sources and that ventilation
is available.
•
In addition to conventional charging procedures, the following requirements shall be followed.
EN
