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Recovery of refrigerant

Service cylinder capacity

By Barney Richardson

There is a lot of talk about this topic relating to both air conditioning units and refrigeration plants. But what does it mean?

Refrigerants are an important part of cooling in air conditioning and refrigeration as part of the heat transfer process. Recovering the refrigerant in a safe and efficient way reduces the amount of harmful HFC and HCFC refrigerants entering the atmosphere and environment.

Then there is the Montreal Protocol and amendments alongside the regulation published by the Department of Environment Forestry and Fisheries. These all emphasise regulation of the release of refrigerants. This is all beneficial to the environment through preventing global warming and Ozone depletion.

Before recovering refrigerant and before starting the recovery machine, do the following:

Be aware of the type of machine, does it recover only vapour or will it recover vapour and liquid? Check the manufacturers’ procedure for operation. This is important because you don’t want liquid to enter the compressor.

To prevent overfilling, cylinders should not be filled to more than 80% of their internal volume and capacity mass as shown on the cylinder. Image credit: Barney Richardson

Examine the service valves. Are they are open or closed? Purge the connecting hoses, then recover any refrigerant that may still be in the machine. A new filter drier must be used for each new refrigerant recovery operation. The service/recovery cylinder must be evacuated so that it is empty before starting the transfer of refrigerant into the cylinder. Also check the oil in the compressor. The oil should have been changed after the previous recovery.

Qualified practitioners use these recovery machines before starting a repair or modification as part of maintenance on an air conditioner or refrigeration system. The refrigerant recovered into a service cylinder must be checked for contamination before reuse. The refrigerant suppliers offer a testing service.

Only a recovery machine must be used to recover refrigerant from a refrigeration circuit. The release of refrigerant is wrong and illegal. A vacuum pump cannot be not used for recovery of refrigerant and must only be used to evacuate a refrigeration system in preparation for pressure testing and charging with the recovered refrigerant or new refrigerant.

Refrigerant recovery machines are used to remove refrigerants from refrigeration equipment in compliance with standards. The practitioner can recover refrigerant from the refrigeration circuit into the service cylinder and  when the repair is complete, recharge the client’s equipment with the recovered refrigerant provided it is not contaminated.

To prevent overfilling, cylinders should not be filled to more than 80% of their internal volume and capacity mass as shown on the cylinder. See the photograph for a typical service cylinder with the filling capacity for common refrigerants. A scale should always be used to weigh the cylinder while filling, to ensure that over-filling does not happen.

Should the cylinder become over-filled, the internal pressure can increase with even a small rise in temperature and create a dangerous situation with possible bursting or explosion that will cause serious damage and injury.

Where the refrigeration system is large, the smaller recovery units may not cope with the volume of refrigerant and recovery could take hours. A Gas offers a service for large capacity refrigeration systems from which  refrigerant can be recovered efficiently and quickly. 


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