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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.
15. 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 pipe-work are to take place. Ensure that the outlet for the vacuum pump is not close
to any ignition sources and there is a ventilation available.
16. 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.
17. 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.