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

Under USCG National Maritime Center examination standards, the accepted correct answer is: liquid recovery using a liquid pump, followed by vapor recovery using a vacuum pump based recovery unit.