to the refrigerant employed and the appropriate percentage of
gas (25 % maximum) is confirmed. Leak detection fluids are
suitable for use with most refrigerants but the use of detergents
containing chlorine shall be avoided as the chlorine may react
with the refrigerant and corrode the copper pipe-work. If a leak
is suspected, all naked flames shall be removed/ extinguished. If
a leakage of refrigerant is found which requires brazing, all of
the refrigerant shall be recovered from the system, or isolated
(by means of shut off valves) in a part of the system remote
from the leak. O
xygen free nitrogen (ofn) shall then be
purged through the system both
before and during the
brazing process.
Removal and evavuation. When breaking into the refrigerant
circuit to make repairs or for any other purpose conventional
procedures shall be used. However, it is important that best
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
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