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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 ventilation available.
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
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