1918
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.
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.
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