Hello, I am new to the forum but have read many posts and found a lot of useful information. I recently had to recover approximately 600lbs of refrigerant from a Trane water-cooled screw chiller and was curious about different recovery methods that technicians use.
While on this particular job I used the standard "push-pull" method to recover the liquid in the system (About 150lbs) and then proceeded to recover the remaining (~450lbs) vapor using the standard vapor recovery method. This took nearly 8 hours, even with two recovery machines.
My question is, since the chiller had an operational compressor, would it be possible to set up a liquid recovery as such:
Attach liquid port of recovery cylinder to liquid line service port of chiller.
Attach vapor port of recovery cylinder to suction service port of chiller.
Run compressor and recover liquid from circuit (of course monitoring amount recovered with scales and gauges, and having ensured proper water flow through chiller) Basically I want to run the compressor so I know where the liquid in the circuit is, and can recover a large percentage of refrigerant as a liquid, rather than waiting hours and hours to pull out the vapor.
Would recovering refrigerant in this manner pose a threat to the oil flow while compressor was running because of any problems with the differential that the oil needs to move? I have been told that you can recover up to about 80% of the unit's charge as liquid in this manner before low differential pressure poses a threat.
Thanks!
HVAC/R - Recovering Liquid Refrigerant 
Re: HVAC/R - Recovering Liquid Refrigerant
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