MAINTENANCE, REPAIR, DECOMMISSIONING, DISPOSAL
45
Evacuation and Removal of the Refrigerant
Conventional procedures shall be used if the refrigerant circuit (sealed system) is to be opened. Refrigerant
R290 is flammable, therefore the following procedure shall be followed:
◼ Evacuate the refrigerant circuit (sealed system) and remove the refrigerant.
◼ Purge the refrigerant circuit (sealed system) with nitrogen for five (5) minutes.
◼ Evacuate the refrigerant circuit (sealed system) again.
◼ Remove parts to be replaced by cutting, not by flame.
The refrigerant shall be recovered into the correct recovery cylinders. The sealed system shall be purged with
nitrogen to render the heat pump safe. This process may need to be repeated several times. Compressed air
or oxygen shall not be used for purging the refrigerant lines.
Purging shall be achieved by breaking the vacuum in the system with nitrogen 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 nitrogen charge is used, the system
shall be vented down to atmospheric pressure to enable service work to take place. This process is vital if
brazing operations on the pipe work are to take place.
The outlet of the vacuum pump must not be close to any potential ignition sources, and the point of discharge
is well ventilated.
Good practise is to be followed when removing refrigerant from the sealed system during servicing or
decommissioning to ensure all refrigerant is removed safely.
• Only appropriate refrigerant recovery cylinders shall be used and labelled for R290 refrigerant.
• A recovery cylinder shall be complete with pressure relief valve and associated shut-off valves in good
working order, evacuated and if possible, cooled before recovery occurs.
• The recovery equipment shall be in good working order and suitable for the recovery of R290 refrigerant.
• Hoses shall be complete with leak-free disconnect couplings and in good condition.
• The recovery machine is to be checked to ensure it is in satisfactory working order, has been properly
maintained and that any associated electrical components are sealed to prevent ignition in the event of a
refrigerant release.
• Calibrated weighing scales shall be available and in good working order.
Recovered refrigerant shall be disposed of correctly and a waste transfer note arranged. Do not mix
refrigerants in recovery cylinders.
Charging Procedure
Prior to recharging the sealed system, pressure test the system with nitrogen.
In addition to conventional charging procedures, the following should be noted:
• Ensure the contamination of different refrigerants does not occur when using charging equipment. Hoses
and lines should be as short as possible to minimise the amount of refrigerant in them.
• Charging cylinders shall be kept in an appropriate position according to their instructions.
• Ensure the refrigerating system is earthed prior to charging the system with refrigerant.
• If not already labelled, label the system when charging is complete.
• Exercise extreme care so as not to overfill the refrigerating system.
Leak test the sealed system upon completion of the charging but prior to commissioning, and again after
commissioning prior to leaving the site.
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