Leak detection methods. T
he
following
leak
detection
methods
are
deemed
acceptable
for
systems
containing flammable refrigerants.
Electronic leak detectors shall be used to detect flammable
refrigerants, but the sensitivity may not be adequate, or may need re-
calibration. (detection equipment shall be calibrated in a refrigerant-
free area). Ensure that the detector is not a potential source of ignition
and is suitable for the refrigerant used. L
eak
detection
equipment
shall
be
set
at
a
percentage
of
the if of
the
refrigerant and shall be
calibrated 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.
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