Tarrington House MAC2320C Manual Del Usuario página 12

exceed the permissible voltage and current permitted
for the equipment in use.
Intrinsically safe components are the only types that
GB
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 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.
All manuals and user guides at all-guides.com
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 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.
• Ensure that contamination of different
refrigerants does not occur when using charging
equipment. Hoses or lines shall be as short as
possible to minimise the amount of refrigerant
contained in them.
• Cylinders shall be kept upright.
• Ensure that the refrigeration system is earthed
prior to charging the system with refrigerant.
• Label the system when charging is complete (if
not already).
• Extreme care shall be taken not to overfill the
refrigeration system.
Prior to recharging the system it shall be pressure
tested with OFN. The system shall be leak tested on
completion of charging but prior to commissioning. A
follow up leak test shall be carried out prior to leaving
the site.
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