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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 according to IEC 60079-15:2010.
Information about the correct working procedures:
a) Commissioning
·Ensure that the floor area is sufficient for the refrigerant charge or that the
ventilation duct is assembled in a correct manner.
·Connect the pipes and carry out a leak test before charging with refrigerant. ·Check
safety equipment before putting into service.
b) Maintenance
·Portable equipment shall be repaired outside or in a workshop specially equipped for
servicing units with flammable refrigerants.
·Ensure sufficient ventilation at the repair place.
·Be aware that malfunction of the equipment may be caused by refrigerant loss and a
refrigerant leak is possible.
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