10
CAUTION
2.
2-10. Checks to electrical devices
Repair and maintenance to electrical components shall include initial safety checks and component inspection procedures.
Initial safety checks shall include but not limit to:-
- That capacitors are discharged: this shall be done in a safe manner to avoid possibility of sparking.
- That there is no live electrical components and wiring are exposed while charging, recovering or purging the system.
- That there is continuity of earth bonding.
At all times the manufacturer’s maintenance and service guidelines shall be followed.
If in doubt consult the manufacturer’s technical department for assistance.
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, an adequate temporary solution shall be
used.
The owner of the equipment must be informed or reported so all parties are advised thereinafter.
3.
Repairs to sealed components
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.
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.
NOTE:
The use of silicon sealant may inhibit the effectiveness of some types of leak detection equipment.
Intrinsically safe components do not have to be isolated prior to working on them.
4.
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 flammable atmosphere.
The test apparatus shall be at the correct rating.
Replace components only with parts specified by the manufacturer. Unspecified parts by manufacturer may result ignition of
refrigerant in the atmosphere from a leak.
5.
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.
6.
Detection of flammable refrigerants
Under no circumstances shall potential sources of ignition be used in the searching 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.
- No leaks shall be detected when using detection equipment with a sensitivity of 5 grams per year of refrigerant or better under
a pressure of at least 0,25 times the maximum allowable pressure (>1.04MPa, max 4.15MPa) for example, a universal sniffer.
- Electronic leak detectors may 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 also suitable for use with most refrigerants, for example, bubble method and fluorescent method
agents. 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. The precautions in #7 must be followed to remove
the refrigerant.
