Question

Your recovery/recycling machine has R502 refrigerant in it. You now have to recover refrigerant from a unit with R22. What must be done before the R22 refrigerant can be recovered/recycled?

1) Nothing, as long as the recovery machine is not full
2) Change the expansion valve on the recovery machine
3) Change the filter and expansion valve on the recovery machine
4) Recover as much of the R502 from the recovery unit as possible, change filter and evacuate

Answer 1

When switching from recovering R502 to R22 refrigerant, the recovery machine must have the R502 recovered, the filter changed, and the machine evacuated to avoid cross-contamination and equipment damage.

Step-by-step explanation:

The student's question relates to what must done before recovering R22 refrigerant using a machine that already has R502 refrigerant in it. The correct procedure is to recover as much of the R502 refrigerant from the recovery unit as possible, then change the filter, and evacuate the machine properly before using it to recover R22 refrigerant. This ensures that there is no cross-contamination between different types of refrigerants, which can cause damage to the recovery equipment and the HVAC systems involved, as well as violate regulations regarding the mixing of refrigerants.