Which sign most strongly suggests a leak in an operating R-11 centrifugal chiller?
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
Which sign most strongly suggests a leak in an operating R-11 centrifugal chiller?
- High superheat with oil stains on a hermetic compressor
- Frost forming on the liquid line
- Chilled water leaving colder than its set point
- The purge unit runs much more than usualCorrect answer
Why “The purge unit runs much more than usual” is correct
Most of a low-pressure chiller runs below atmospheric pressure, so leaks let air in rather than letting refrigerant out. The purge unit has to run to remove that air, so excessive purging is the main warning sign of a leak.
Source: EPA: Test Topics
Why the other answers are wrong
- High superheat with oil stains on a hermetic compressor — Those are typical leak signs on high-pressure systems, not the classic low-pressure sign.
- Frost forming on the liquid line — Frost on a liquid line points to a restriction, not to air leaking into a low-pressure chiller.
- Chilled water leaving colder than its set point — Overcooling is a control issue and does not indicate a refrigerant leak.
Practice more of this
More EPA 608 Type III practice questions, or see every EPA 608 practice test.
Unofficial, not affiliated with the EPA or any EPA-approved certifying organization. Questions are original practice written from public EPA material, not real exam questions.