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of the refrigerant and shall be calibrated to the refrigerant em-
ployed, 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/extin-
guished.
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. For appliances containing flammable refrigerants, oxygen free
nitrogen (OFN) shall then be purged through the system both be-
fore and during the brazing process.
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 prac-
tice is followed since flammability is a consideration. The 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.
For appliances containing flammable refrigerants, the system shall
be "flushed" with OFN to render the unit safe. This process may
need to be repeated several times.
Compressed air or oxygen shall not be used for purging refrigerant
systems.
For appliances containing flammable refrigerants, flushing shall be
achieved by breaking the vacuum in the system with OFN and
continuing to fill until the working pressure is achieved, then vent-
ing to atmosphere, and finally pulling down to a vacuum.
This process shall be repeated until no refrigerant is within the sys-
tem.
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 ig-
nition sources and that ventilation is available.
Charging procedures
In addition to conventional charging procedures, the following re-
quirements 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.
– Label the system when charging is complete (if not already).
– Extreme care shall be taken not to overfill the refrigeration sys-
tem.
Prior to recharging the system, it shall be pressure-tested with the
appropriate purging gas.
The system shall be leak-tested on completion of charging but pri-
or 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 techni-
cian 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.
a) Become familiar with the equipment and its operation.
b) Isolate system electrically.
c) Before attempting the procedure, ensure that:
• mechanical handling equipment is available, if required, for han-
dling refrigerant cylinders;
• all personal protective equipment is available and being used
correctly;
• the recovery process is supervised at all times by a competent
person;
• recovery equipment and cylinders conform to the appropriate
standards.
d) Pump down refrigerant system, if possible.
e) If a vacuum is not possible, make a manifold so that refrigerant
can be removed from various parts of the system.
f) Make sure that cylinder is situated on the scales before recov-
ery takes place.
g) Start the recovery machine and operate in accordance with
manufacturer's instructions.
h) Do not overfill cylinders. (No more than 80 % volume liquid
charge).
i) Do not exceed the maximum working pressure of the cylinder,
even temporarily.
j) When the cylinders have been filled correctly and the process
completed, make sure that the cylinders and the equipment are
removed from site promptly and all isolation valves on the
equipment are closed off.
k) Recovered refrigerant shall not be charged into another refriger-
ation system unless it has been cleaned and checked.
Labelling
Equipment shall be labelled stating that it has been de-commis-
sioned and emptied of refrigerant. The label shall be dated and
signed. For appliances containing flammable refrigerants, ensure
that there are labels on the equipment stating the equipment con-
tains flammable refrigerant.
Recovery
When removing refrigerant from a system, either for servicing or
decommissioning, it is recommended good practice that all refrig-
erants are removed safely.
When transferring refrigerant into cylinders, ensure that only appro-
priate refrigerant recovery cylinders are employed. Ensure that the
correct number of cylinders for holding the total system charge are
available. All cylinders to be used are designated for the recovered
refrigerant and labelled for that refrigerant (i.e. special cylinders for
the recovery of refrigerant). Cylinders shall be complete with pres-
sure-relief valve and associated shut-off valves in good working or-
der. Empty recovery cylinders are evacuated and, if possible,
cooled before recovery occurs.
The recovery equipment shall be in good working order with a set
of instructions concerning the equipment that is at hand and shall
be suitable for the recovery of all appropriate refrigerants including,
when applicable, flammable refrigerants. In addition, a set of cali-
brated weighing scales shall be available and in good working or-
der. Hoses shall be complete with leak-free disconnect couplings
and in good condition. Before using the recovery machine, check
that it is in satisfactory working order, has been properly main-
tained and that any associated electrical components are sealed to
prevent ignition in the event of a refrigerant release. Consult manu-
facturer if in doubt.
The recovered refrigerant shall be returned to the refrigerant sup-
plier in the correct recovery cylinder, and the relevant waste trans-
fer note arranged. Do not mix refrigerants in recovery units and es-
pecially not in cylinders.
If compressors or compressor oils are to be removed, ensure that
they have been evacuated to an acceptable level to make certain
that flammable refrigerant does not remain within the lubricant. The
evacuation process shall be carried out prior to returning the com-
pressor to the suppliers. Only electric heating to the compressor
body shall be employed to accelerate this process. When oil is
drained from a system, it shall be carried out safely.
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