Oceanic OCEACLIM140W1 Guide D'utilisation page 49

detector is not a potential source of ignition and is suitable for the refrigerant used. Leak
detection equipment shall be set at a percentage of the LFL of the refrigerant and shall be
calibrated to the refrigerant employed 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/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.
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 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 or lines shall be as short as possible to minimize 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) 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; 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.
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