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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 –conven-
tional procedures shall be used. However, it is important that best practice is followed since
flammability is a consideration. Thefollowing 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.
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 orlines 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. 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. lsolate system electrically.
c. Before attempting the procedure ensure that: mechanical handling equipment is availa ble,
if required, for handling refrigerant cylinders; all personal protective equipment is availa
ble and being used correctly; the recovery process is supervised at all limes by a competent
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