Black+Decker BXAC12000E, Manual

Page: 12 / 172

ENGLISH (Original instructions)
12
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 equip-
ment 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 effec-
tiveness 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 COMPO-
NENTS
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 REFRIGER-
ANTS
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 cal-
ibrated in a refrigerantfree 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 pipework. 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 fol-
lowed 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 cylin-
ders. 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 no refrigerant is within the system. When the
final OFN charge is used, the system shall be vented down
to atmospheric pressure to enable work to take place. This
operation is absolutely vital if brazing operations on the
pipework are to take place.
Ensure that the outlet for the vacuum pump is not close to
any ignition sources and there is ventilation available.
CHARGING PROCEDURES
In addition to conventional charging procedures, the
following requirements shall be followed.