8
SAFETY INSTRUCTIONS
Initial safety checks shall include:
– Capacitors are discharged: this shall be done in a safe manner to avoid possibility of sparking.
– No live electrical components and wiring are exposed while charging, recovering or purging the system.
– Continuity of earth bonding.
During repairs to sealed components, all electrical supplies shall be disconnected from the equipment being
worked upon prior to any removal of sealed covers, etc.
Particular attention shall be paid to the following to ensure that by working on electrical components, the
casing is not altered in such a way that the level of protection is affected.
This shall include damage to cables, excessive number of connections, terminals not made to original
specification, damage to seals, incorrect fitting of glands, etc.
Ensure that apparatus is mounted securely.
Ensure that seals or sealing materials have not degraded such that they no longer serve the purpose of
preventing the ingress of flammable atmospheres.
Replacement parts shall be in accordance with the manufacturer’s specifications.
If it is absolutely necessary to have an electrical supply to equipment during servicing, then a permanently
operating form of leak detection shall be located at the most critical point to warn of a potentially hazardous
situation.
Repairs to sealed components
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.
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.
Repair to intrinsically safe components
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 ageing or continual vibration from
sources such as compressors or fans.
Cabling Check
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.
Detection of flammable refrigerants
The following leak detection methods are deemed acceptable for systems containing flammable refrigerants.
Ensure that the detector is not a potential source of ignition and is suitable for the refrigerant used.
If a leak is suspected, all naked flames shall be removed/extinguished.
Oxygen free nitrogen (OFN) shall then be purged through the system both before and during the brazing process.
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.
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.
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.
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.)
Leak detection methods
Removal and evacuation
