practice is followed since flammability is a consideration. T
he
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.
T
his
process
may
need
to
be
repeated
several
times.
Compressed
air or oxygen shall not be used for this task.
F
lushing
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. T
his
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. I
n 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. L
abel
the
system
when
charging
is
complete
(if
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