Purge units: EPA 608 Practice Questions

What is the main job of a purge unit on a low-pressure chiller?

Air and moisture leaking into the chiller collect in the condenser. The purge unit removes them while returning as much refrigerant as possible.

What is the advantage of a high-efficiency purge unit?

Older purge units released significant refrigerant with the air. High-efficiency units separate the refrigerant and vent mostly air.

Why do many chiller owners record purge unit run time or pump-out counts?

Purge activity tracks how much air enters the chiller, so a rising trend points to a leak before much refrigerant is lost.

What happens to a chiller's condenser pressure when non-condensables build up?

Non-condensables add their own pressure and take up condenser surface, so head pressure rises and the compressor works harder.

Refrigerant released through a purge unit's exhaust affects which owner obligation under 82.157?

Refrigerant lost through purging is part of the leak rate. Only purged refrigerant sent to destruction at 98% efficiency or greater may be excluded.

From which part of the chiller does the purge unit normally draw vapor?

Non-condensables gather at the top of the condenser, so the purge pickup is located there.

Besides air, what else does a purge unit help remove from a low-pressure chiller?

Moisture enters with leaking air. Many purge units separate and drain water or hold it in a drier.

How does a high-efficiency purge unit keep refrigerant out of its exhaust?

A high-efficiency purge unit chills the air and refrigerant mixture so the refrigerant condenses and drains back into the chiller, and it discharges mostly air. Older designs released much more refrigerant with the air.

A chiller purge unit runs constantly, even after the operator resets it. What should be checked first?

Constant purging means air keeps entering. Leak-check the chiller (and the purge unit itself) rather than just resetting it.

Where is a purge unit's exhaust vent typically routed?

Purge exhaust carries air and a small amount of refrigerant, so it is piped outdoors away from people and air intakes.