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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.
Oxygen free nitrogen (OFN) shall then be purged through the system both before and
during the brazing process.
28. 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 pipe-work are to take
place.
Ensure that the outlet for the vacuum pump is not close to any ignition sources and
there is ventilation available.
29. 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.
30. DECOMMISSIONING
Before carrying out this procedure, it is essential that the technician 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 handling refrigerant
cylinders;
• All personal protective equipment is available and being used correctly;
EN - 9
SECCOPROF 30P - 40P
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