The most cost-effective method of recovering refrigerant from a low pressure chiller with more than 500 lbs of refrigerant and to meet EPA requirements is to recover the refrigerant using what protocol?

Correct Answer: Option D — liquid recovery using a liquid pump, followed by vapor recovery using a vacuum pump based recovery unit

Recovering over 500 lbs of refrigerant from a low-pressure chiller requires maximizing efficiency per EPA guidelines. Initiating bulk liquid recovery via a liquid pump removes the vast majority of refrigerant rapidly, followed by deep vacuum vapor recovery to extract residual gas efficiently.