Taurus ALPATEC AC 3100 KT, Manual, Page: 24 / 176

itors 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 absolute-
ly 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 compo-
nents, 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, incor-
rect fitting of glands, etc. Ensure that appara-
tus is mounted securely. Ensure that seals or
sealing materials have not degraded such that
they no longer serve the purpose of prevent-
ing 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 COMPO-
NENTS
- Do not apply any permanent inductive or ca-
pacitance 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 REFRIGE-
RANTS
- 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 contain-
ing 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 refriger-
ant-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 refrig-
erant 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 contain-
ing 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 – con-
ventional 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 refriger-
ant; 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