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3)
Evacuate.
4)
Purge again with inert gas.
5)
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 ventilation available.
8. Charging procedures
In addition to conventional charging procedures, the following requirements shall be
followed.
1)
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.
2) Cylinders shall be kept upright.
3) Ensure that the refrigeration system is earthed prior to charging the system with
refrigerant.
4) Label the system when charging is complete (if not already).
5) 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
