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Idiomas disponibles
Idiomas disponibles
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.
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.
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.
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.
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.
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 recalibration. (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.
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 finally pulling
down to a vacuum. This process shall be repeated until
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