Pro-Elec PELL0374 - Repair to Intrinsically Safe Components; Detection of Flammable Refrigerants; Removal and Evacuation

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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 ammable atmosphere. The test apparatus shall be at the
correct rating.
• Replace components only with parts specied by the manufacturer. Other parts
may result in the ignition of refrigerant in the atmosphere from a leak.
Cabling
• Check that cabling will not be subject to wear, corrosion, excessive pressure,
vibration, sharp edges or any other adverse environmental e󰀨ects. The check shall
also take into account the e󰀨ects of aging or continual vibration from sources such
as compressors or fans.
Detection of ammable 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 ame) shall not be used.
Leak detection methods
• The following leak detection methods are deemed acceptable for systems
containing ammable refrigerants.
• Electronic leak detectors shall be used to detect ammable 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 conrmed.
• Leak detection uids 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 ames 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 o󰀨 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 ammability is a consideration. The following
procedure shall be adhered to:
1. Remove refrigerant.
2. Purge the circuit with inert gas.
3. Evacuate.
4. Purge again with inert gas.
5. Open the circuit by cutting or brazing.
• The refrigerant charge shall be recovered into the correct recovery cylinders. The
system shall be “ushed” with OFN to render the unit safe. This process may need