HVAC - EPA Certification Practice Exam

Using the liquid phase recovery technique when performing refrigerant recovery is effective in minimizing the loss of oil. When refrigerant is recovered in its liquid state, it allows for a larger proportion of lubricating oil, which is mixed with the refrigerant in the system, to be recovered along with the refrigerant itself. This is because the liquid refrigerant is more likely to carry the dissolved oil with it, reducing the amount that remains in the compressor and system.

In contrast, vapor phase recovery typically results in a greater loss of oil. During this process, only the refrigerant vapor is removed, leading to more oil being left behind due to its heavier nature and tendency to stay in the system.

Direct venting is not an acceptable method for recovering refrigerant as it involves releasing refrigerant into the atmosphere, which is illegal and harmful to the environment. Fast recovery does not specifically address the oil recovery aspect and primarily focuses on the speed of the recovery process rather than the efficiency of oil retention.

Therefore, liquid phase recovery is the most effective technique for minimizing oil loss during refrigerant recovery.