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Idiomas disponibles
Idiomas disponibles
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.
5 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.
6 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.
7 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.
8 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 minimize 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.
9 DECOMMISSIONING
Before carrying out this procedure, it is essential that the technician is completely familiar with the equipment and all
its detail. It is recommended good practice that all refrigerants are recovered safely. Prior to the task being carried
out, an oil and refrigerant sample shall be taken in case analysis is required prior to re-use of reclaimed refrigerant.
It is essential that electrical power is available before the task is commenced.
1.
Become familiar with the equipment and its operation.
Isolate system electrically.
2.
Before attempting the procedure ensure that :mechanical handling equipment is available, if required, for
3.
handling refrigerant cylinders; all personal protective equipment is available and being used correctly; the
recovery process is supervised at all times by a competent person; recovery equipment and cylinders
conform to the appropriate standards.
S. 165
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