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lf 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. Oxygen free
nitrogen (OFN) shall then be purged through the system both before and during the brazing process.
7 REMOVAL AND EVACUATION
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. 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. 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 this task. Flushing 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. This 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 pipework are to take place. Ensure
that the outlet tor the vacuum pump is not close to any ignition sources and !here is ventilation available.
8 CHARGING PROCEDURES
In 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. Label 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. The 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.
9 DECOMMISSIONING
Before carrying out this procedure, it is essential that the technician is completely
familiar with the equipment and all its detail. lt 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. lt is essential that 4 GB electrical power is available before the task is commenced.
a) Become familiar with the equipment and its operation.
b) lsolate system electrically.
c) Before attempting the procedure ensure that: mechanical handling equipment is available, if required, for
handling refrigerant cylinders;
d) All personal protective equipment is available and being used correctly; the recovery process is supervised at
all times by a competent person;
e) recovery equipment and cylinders conform to the appropriate standards.
f) Pump down refrigerant system, if possible.
g) lf a vacuum is not possible, make a manifold so that refrigerant can be removed from various parts of the
system.
h) Make sure that cylinder is situated on the scales before recovery takes place.
i) Start the recovery machine and operate in accordance with manufacturer’s instructions.
j) Do not overfill cylinders. (No more than 80 % volume liquid charge).
k) Do not exceed the maximum working pressure of the cylinder, even temporarily.
l) 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.
m) Recovered refrigerant shall not be charged into another refrigeration system unless it has been cleaned and
checked.
10 LABELLING
Equipment shall be labelled stating that it has been de-commissioned and emptied of refrigerant. The label
shall be dated and signed. Ensure that there are labels on the equipment stating the equipment contains
flammable refrigerant.
11 RECOVERY
When removing refrigerant from a system, either for servicing or decommissioning, il is recommended good
practice that all refrigerants are removed safely. When transferring refrigerant into cylinders, ensure that
only appropriate 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 pressure relief valve and associated shut-off valves in good working order. 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 flammable refrigerants. In addition, a set of calibrated
weighing scales shall be available and in good working order. Hoses shall be complete with leak-free disconnect
couplings and in good condition. Before using the recovery machine, check that il is in satisfactory working
GB
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