Which method should be tried first?

Leak detection · EPA 608 Type III. The correct answer, and the reasoning behind it.

Pressurizing low-pressure systems for leak tests, signs of leaks, inspections and reports.

The question

A technician needs to raise the pressure inside an idle R-123 chiller to leak test it. Which method should be tried first?

• AHot water in the tubes or a built-in heater such as PrevacCorrect answer
• BDry nitrogen fed straight into the shell from a regulated cylinder
• CA trace of R-22 pushed with nitrogen
• DCompressed air from the shop line

Why “Hot water in the tubes or a built-in heater such as Prevac” is correct

EPA's test topics put heating first for low-pressure systems: run hot water through the tubes or use a built-in heating and pressurization device such as Prevac. Warming the refrigerant raises its own pressure, so nothing has to be purged out afterward. Nitrogen comes second.

Source: EPA: Test Topics

Why the other answers are wrong

• Dry nitrogen fed straight into the shell from a regulated cylinder — Nitrogen is the second choice, used only when heating cannot raise the pressure enough.
• A trace of R-22 pushed with nitrogen — Trace gas with nitrogen is a high-pressure leak test practice, not the first choice for a low-pressure chiller.
• Compressed air from the shop line — Compressed air brings in moisture and noncondensables and is not a leak test gas for chillers.

Practice more of this

More EPA 608 Type III practice questions, or see every EPA 608 practice test.