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Idiomas disponibles
DETECTION OF FLAMMABLE REFRIGERANTS
Under no circumstances should 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) should not be used.
LEAK DETECTION METHODS
• The following leak detection methods are deemed
acceptable for systems containing flammable
refrigerants. Electronic leak detectors should be
used to detect flammable refrigerants, but the
sensitivity may not be adequate or may need
re-calibration. (Detection equipment should
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 should be set at a
percentage of the Lower Flammability Limit (LFL)
of the refrigerant. It should be calibrated to the
refrigerant employed and until 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 should be avoided as the chlorine may
react with the refrigerant and corrode the copper
pipework.
• If a leak is suspected, all naked flames should be
removed/extinguished. If a leakage of refrigerant
is found that requires brazing, all the refrigerant
should 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)
should 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 should be used. However, it is important
that best practice is followed since flammability is a
consideration. Opening of the refrigeration systems
should not be done by brazing.
The following removal procedures should be
adhered to:
1.
Remove refrigerant.
2. Purge the circuit with inert gas.
3. Evacuate.
4. Purge again with inert gas.
5. Open the circuit by cutting or brazing.
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SAFETY CONTINUED
• The refrigerant charge should be recovered into
the correct recovery cylinders. The system should
be flushed with OFN to render the unit safe. This
process may need to be repeated several times.
Compressed air or oxygen should not be used for
this task.
• Flushing should 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 should be repeated until
no refrigerant is within the system.
• When the final OFN charge is used, the system
should 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 ventilation is
available.
CHARGING PROCEDURES
In addition to conventional charging procedures, the
following requirements should be followed:
• Ensure that contamination of different refrigerants
does not occur when using charging equipment.
• Hoses or lines should be as short as possible to
minimize the amount of refrigerant contained in
them.
• Cylinders should be kept upright.
• Ensure that refrigeration system is earthed prior to
charging system with refrigerant.
• Label the system when charging is complete (if not
already).
• Extreme care should be taken not to overfill the
refrigeration system.
• Prior to recharging the system, it should be
pressure-tested with OFN. The system should be
leak-tested on completion of charging but prior
to commissioning. A follow-up leak test should be
carried out prior to leaving the site.
0124 IH-11032
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