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Precautions
9. 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.
10. 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.
11. Leak detection methods
Ensure all service equipments are R290 rated including vacuum and recovery pump, leak
detector and pressure gauges.
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.)
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.
12. 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 with the use of R290 rated
recovery equipment. 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 pipe-work are to take place. Ensure that the
outlet for the vacuum pump is not close to any ignition sources and there is ventilation available.
13. 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.
Safety
Precautions
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