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Information on servicing (Continued)
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, an 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
• 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.
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 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.
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 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 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/ 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. Oxygen free nitrogen (OFN) shall
then be purged through the system both before and
during the brazing process.
15. 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 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.
The refrigerant charge shall be recovered into the
correct recovery cylinders. The system shall be flushed
with OFN to render the unit safe. This process may
need to be repeated several times. Compressed air or
oxygen shall not be used for this task. Flushing shall be
achieved by breaking the vacuum in the system with
OFN and continuing to fill until the working pressure is
achieved, then venting to atmosphere, and
General Safety Instructions (Continued)
