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7IMPORTANT SAFETY INSTRUCTIONS
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.
Removal of refrigerant shall be according
to Removal and evacuation.
11. Removal and evacuation
When breaking into the refrigerant circuit
to make repairs – or for any other
purpose–conventional procedures shall
be used. However, for flammable
refrigerants it is important that best
practice be followed, since flammability is
a consideration. The following procedure
shall be adhered to:
a) safely remove refrigerant following local
and national regulations;
b) purge the circuit with inert gas;
c) evacuate (optional for A2L);
d) purge with inert gas (optional for A2L);
e) open the circuit by cutting or brazing.
The refrigerant charge shall be recovered
into the correct recovery cylinders if
venting is not allowed by local and
national codes. For appliances containing
flammable refrigerants, the system shall
be purged with oxygen-free nitrogen to
render the appliance safe for flammable
refrigerants. This process might need to
be repeated several times. Compressed
air or oxygen shall not be used for
purging refrigerant systems. For
appliances containing flammable
refrigerants, refrigerants purging shall be
achieved by breaking the vacuum in the
system with oxygen-free nitrogen and
continuing to fill until the working
pressure is achieved, then venting to
atmosphere, and finally pulling down to a
vacuum (optional for A2L). This process
shall be repeated until no refrigerant is
within the system (optional for A2L).
When the final oxygen-free nitrogen
charge is used, the system shall be vented
down to atmospheric pressure to enable
work to take place. Ensure that the outlet
for the vacuum pump is not close to any
potential ignition sources and that
ventilation is available.
ensuring that this will not exceed the
permissible voltage and current
permitted for the equipment in use.
Intrinsically safe components are the only
types that can be worked on while live in
the presence of a flammable atmosphere.
The test apparatus shall be at the correct
rating. Replace components only with
parts specified by the manufacturer.
Other parts may result in the ignition of
refrigerant in the atmosphere from a leak.
9. Cabling
Check that cabling will not be subject to
wear, corrosion, excessive pressure,
vibration, sharp edges or any other
adverse environmental effects. The check
shall also take into account the effects of
aging or continual vibration from sources
such as compressors or fans.
10.Detection of flammable refrigerants
Under no circumstances shall potential
sources of ignition be used in the
searching for or detection of refrigerant
leaks. A halide torch (or any other
detector using a naked flame) shall not be
used.
The 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. Leak detection equipment shall be
set at a percentage of the LFL 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
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