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6. Maintenance – Maintenance – Mantenimiento – Wartung -
Manutenzione
should be calibrated in a refrigerant-free area). ) Care should be taken to ensure that
the detector is not a potential source of ignition and that it is suitable for the
refrigerant being used. Leak detection equipment should be set to a percentage of
the LFL of the refrigerant and should be calibrated to the refrigerant used and the
appropriate percentage of gas (25% maximum) confirmed.
Leak detection fluids are suitable for most refrigerants, but the use of detergents
containing chlorine should be avoided, as chlorine can react with the refrigerant and
corrode the copper piping.
If a leak is suspected, all open flames should be removed/extinguished.
If a refrigerant leak requiring soldering is found, all refrigerant should be recovered
from the system or isolated (with shut-off valves) in a portion of the system away
from the leak. Oxygen-free nitrogen (OFN) should then be purged from the system
before and during the brazing process.
Removal and evacuation
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When entering the refrigeration system to make repairs or for any other purpose,
conventional procedures should be used. However, it is important to follow best
practices as flammability is a consideration. The following procedure should be
followed:
Remove the refrigerant;
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Purge the system with an inert gas;
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Evacuate;
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Purge again with inert gas;
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- Open the circuit by cutting or brazing.
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The refrigerant charge must be recovered in the appropriate recovery bottles. The
system must be "flushed" with OFN to make the unit safe. This process may need to
be repeated several times. Compressed air or oxygen should not be used for this task.
Flushing should be accomplished by breaking the vacuum in the system with OFN
and continuing to fill until working pressure is reached, then venting to atmosphere,
and finally down to a vacuum. This process should be repeated until there is no
refrigerant left in the system. When the final charge of OFN is used, the system must
be purged to atmospheric pressure to allow the work to proceed. This is absolutely
necessary to perform brazing operations on the piping.
Care must be taken to ensure that the vacuum pump outlet is not near ignition
sources and that ventilation is available.
Labeling
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Each piece of equipment must be labeled to indicate that it has been taken out of
service and emptied of refrigerant. The label must be dated and signed. Please
ensure that the equipment has labels indicating that the equipment contains
flammable refrigerant.
Recovery
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When removing refrigerant from a system, whether for servicing or decommissioning,
it is recommended that all refrigerant be removed safely.
When transferring refrigerant into cylinders, ensure that only appropriate refrigerant
recovery cylinders are used. Ensure that the correct number of cylinders are available
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