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2.
Purge the circuit with inert gas.
3.
Evacuate.
4.
Purge again with inert gas.
Open the circuit by cutting or brazing.
5.
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The refrigerant charge must be recovered from the correct recovery cylinders. The system
must be flushed with oxygen-free nitrogen to render the unit safe. This process may need
to be repeated several times. Oxygen or compressed air must not be used for the task.
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Cleanliness must be achieved by breaking the vacuum in the system with oxygen-
free nitrogen and continuing to fill until working pressure is reached, then venting to
atmosphere, and finally pushing to a vacuum. This process must be repeated until there
is no refrigerant left in the system. When using the oxygen-free nitrogen end-charge,
the system must be vented to atmospheric pressure to allow for work. This operation is
absolutely vital if brazing operations are to take place on pipes.
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Ensure that the vacuum pump outlet is not near any source of ignition and that ventilation
is available.
8. Loading procedure
In addition to conventional loading procedures, the following requirements must be followed.
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Ensure that no contamination of different refrigerants occurs when using the loading
equipment. Hoses or lines should be kept as short as possible to minimise the amount of
refrigerant contained in them.
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Cylinders must be kept in an upright position.
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Ensure that the refrigeration system is grounded before loading the system with
refrigerant.
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Tag the system when charging is complete (if not already).
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Extreme care must be taken to avoid overfilling the cooling system.
Before reloading, the system must be pressure-tested with oxygen-free nitrogen. The system
shall be leak-tested upon completion of loading, but prior to commissioning. A subsequent
leakage test must be carried out before leaving the site.
9. Commissioning
Before carrying out this procedure, it is essential that the technician is thoroughly familiar with
the equipment and all its details. It is recommended good practice that all refrigerants are
safely recovered. Before the task is carried out, a sample of oil and refrigerant should be taken
in case an analysis is required before the recovered coolant is reused. It is essential for there to
be power before starting with the task.
A. It is important to get familiar with the equipment and its operation.
B. Electrically isolate the system.
C. Before attempting the procedure, ensure that
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the mechanical-handling equipment is available, if required, for the handling of refrigerant
cylinders;
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all personal protective equipment is available and correctly used;
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the recovery process is supervised at all times by a competent person;
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cylinders and recovery equipment conform to appropriate standards.
D. Pump the cooling system, if possible.
E. If vacuum is not possible, make a manifold so that refrigerant can be removed from various
parts of the system.
F.
Ensure that the cylinder is positioned on the scale before recovery takes place.
G. Switch on the recovery machine and operate it according to the manufacturer's instructions.
H. Do not overfill cylinders (no more than 80% of the liquid charge by volume).
I.
Do not exceed the maximum working pressure of the cylinder, even temporarily.
J.
When the cylinders have been correctly filled and the process is complete, ensure that
the cylinders and equipment are promptly removed from the site and that all equipment
isolation valves are closed.
K. Recovered refrigerant must not be charged to another refrigeration system, unless
cleaned and checked.
10. Labelling
The equipment must be labelled stating that it has been taken out of service and drained
of refrigerant. The labelling must be dated and signed. Ensure that there are labels on the
equipment stating that the equipment contains flammable refrigerant.
11. Recovery
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When refrigerant is removed from a system, either for service or decommissioning, it is
recommended good practice that all refrigerants are removed safely.
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When transferring refrigerant to cylinders, ensure that only suitable refrigerant-recovery
cylinders are used. Ensure that the correct number of cylinders is available to support
the total load of the system. All cylinders to be used are designated for the refrigerant
recovered and labelled for that refrigerant (i.e., special refrigerant-recovery cylinders).
Cylinders must be completed with pressure-relief valves and associated shut-off valves
in good working order. Empty recovery cylinders are evacuated and, if possible, cooled
before recovery takes place.
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Recovery equipment must be in good working order with a set of instructions concerning
the equipment at hand and must be suitable for the recovery of flammable refrigerants. In
addition, a set of calibrated weighing scales must be available and in good working order.
Hoses must be complete with disconnect couplings free of leakage and in good running
order. Before using the recovery machine, check that it is in good running order, properly
maintained, and that all associated electrical components are sealed to prevent ignition in
the event of refrigerant release. Consult the manufacturer in case of doubt.
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The flammable refrigerant must be returned to the refrigerant supplier in the correct
recovery cylinder, and the applicable waste transfer note must be provided. Do not mix
refrigerants in recovery units and especially not in cylinders.
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