Recovery techniques: EPA 608 Practice Questions

When recovering from a large system, why is liquid recovered before vapor when possible?

Liquid is far denser than vapor, so removing it first greatly shortens recovery time. Vapor is recovered afterward to reach the required level.

Which practice speeds up recovery?

A colder cylinder has lower pressure, so refrigerant flows into it faster. Short, large hoses and removing valve cores also help; never heat a cylinder with a torch.

Why connect the recovery machine to both the high and low sides of a system?

Pulling from both sides removes refrigerant from both sides of the metering device and compressor at once, which speeds recovery.

After the recovery machine reaches the required vacuum, the technician closes the valves and the pressure slowly rises. What does this indicate?

Refrigerant trapped in oil or in liquid pockets keeps boiling off. Wait a few minutes after reaching the level; if pressure rises, recover again before opening.

A technician with a recovery machine rated for A2L refrigerants will use it on R-454B after recovering R-410A. What should be done first?

Clearing the old refrigerant and changing the filter prevents cross-contamination. A machine that is not rated for A2L refrigerants must not be used on R-454B at all.

Which hose setup gives the fastest recovery?

Flow restriction slows recovery. Short, wide hoses and removing Schrader cores with a core-removal tool reduce restriction.

What is the maximum safe fill for a refillable recovery cylinder?

Leave space for the liquid to expand as temperature rises. Fill to no more than 80% and check by weight with a scale or by the cylinder's float switch.

Why should a new or empty recovery cylinder be evacuated before its first use?

Air left in the cylinder becomes non-condensable contamination and raises cylinder pressure. Evacuating it first keeps recovered refrigerant clean.

Why does recovery take longer on a cold day?

Lower temperature means lower saturation pressure, so there is less pressure pushing refrigerant out of the system and into the recovery machine.

A system leaks so badly that the required vacuum cannot be reached. What does the rule require?

Leaking components are isolated where possible. Non-leaking parts go to the normal level; leaking parts go to the lowest level reachable without contaminating the refrigerant, and no higher than 0 psig.