INFORMATION SERVICING
9. Checks to electrical devices
Repair and maintenance to electrical components shall include initial safety checks and component inspection procedures. If a
fault exists that could compromise safety, then no electrical supply shall be connected to the circuit until it is satisfactorily dealt
with. If the fault
cannot be corrected immediately but it is necessary to continue operation, and adequate temporary solution shall be used. This
shall be reported to the owner of the equipment so all parties are advised.
Initial safety checks shall include:
•
that capacitors are discharged: this shall be done in a safe manner to avoid possibility of sparking
•
that there no live electrical components and wiring are exposed while charging, recovering or purging the system;
•
that there is continuity of earth bonding.
10. Repairs to sealed components
10.1 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. 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.
10.2 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 connec-
tions, 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.
11. 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 permissi-
ble voltage and current permitted for the equipment in use. Intrinscially 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.
12. Cabling
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.
13. Detection of flammable 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 flame) shall not be used.
14. 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. 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 or
extinguished. If a leakage of refrigernat 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.
The use of silicon sealant may inhibit the effectiveness of some types of leak detection equipment. Instrinsically
safe components do not have to be isolated prior to working on them.
NOTE:
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Summary of Contents for 20-046
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