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
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. T
he
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.
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.
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