EPA Section 608 Universal Certification ExamType III (Low-Pressure Appliances)Medium
A low-pressure chiller using R-123 has been repaired after a leak. Before being returned to service, what is the maximum allowable pressure the system can be pressurized to for a leak test?
- A30 psig
- BAtmospheric pressure (0 psig) followed by a vacuum check.
- C10 psig
- D0 psig
Show answer & explanationAnswer & explanation
Correct answer: C. 10 psig
Low-pressure chillers should not be pressurized above 10 psig for leak testing. Exceeding this pressure can cause the system's rupture disc to fail, releasing refrigerant.
Why the other options are wrong
- A. 30 psig is too high and risks rupturing the low-pressure chiller's rupture disc, which is typically set at 15 psig.
- B. A vacuum check is part of leak testing, but a positive pressure test is also crucial and has a specific limit.
- D. While 0 psig is safe, it may not provide enough pressure differential to detect smaller leaks effectively.
Low-Pressure Leak Test Max Pressure
For low-pressure chillers, the maximum safe pressure for leak testing with nitrogen or other inert gas is 10 psig to prevent rupture disc activation.
- Max 10 psig for positive pressure leak test.
- Rupture disc typically set at 15 psig.
- Exceeding 10 psig risks refrigerant release.
- Often uses nitrogen for pressurization.
Memory trick: Ten is the 'Top' for low-pressure, don't 'Pop' the disc!