Question 41Refrigeration & AC - 1st Asst/Chief

The correct answer is D) liquid recovery using a liquid pump, followed by vapor recovery using a vacuum pump based recovery unit. The EPA requires that refrigerants be recovered using a combination of liquid and vapor recovery methods to ensure complete recovery and to meet environmental regulations. For a low-pressure chiller with more than 500 lbs of refrigerant, using a liquid pump for the initial liquid recovery, followed by a vacuum pump based vapor recovery unit, is the most cost-effective method to fully recover the refrigerant and comply with EPA requirements. The other options are less effective or do not fully meet the EPA regulations. Option A, using only a vapor recovery machine, may not be sufficient to recover all the liquid refrigerant. Option B, using a vapor recovery unit followed by a liquid pump, is less efficient than the recommended approach. Option C, using only a liquid pump, would not recover the vapor portion of the refrigerant, which is also required.