What is the accepted next step?

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

Hot water in the tubes has raised an idle R-11 chiller only to atmospheric pressure, which is not enough for a leak test. What is the accepted next step?

• AAdd nitrogen until the pressure reaches about 25 psig for a stronger test
• BAdd nitrogen through a regulator, staying at or under 10 psigCorrect answer
• CAdd compressed air through the purge connection
• DRun the compressor to build pressure in the shell

Why “Add nitrogen through a regulator, staying at or under 10 psig” is correct

EPA lists nitrogen as the second choice for pressurizing a low-pressure system for leak testing, after heating. When nitrogen is used, it goes in through a pressure regulator and the test pressure is kept at or below 10 psig, or the manufacturer's lower limit (Trane specifies 8 psig), to protect the rupture disc.

Source: EPA: Test Topics; Trane CTV-SVX05H-EN, R-123 handling guide (8 psig leak test)

Why the other answers are wrong

• Add nitrogen until the pressure reaches about 25 psig for a stronger test — 25 psig is far above the safe limit and risks the rupture disc.
• Add compressed air through the purge connection — Compressed air is not an acceptable leak test gas.
• Run the compressor to build pressure in the shell — The compressor does not raise standing pressure in the shell for a leak test.

Practice more of this

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