EPA Section 608 Universal Certification ExamType III (Low-Pressure Appliances)Hard
A technician is preparing a low-pressure system for a leak test using nitrogen. What is the maximum pressure to which the system should be pressurized with nitrogen for a leak test?
- A10 psig
- BNo more than 10 psig, or 10 inches of Hg vacuum
- C0 psig
- DThe system's design working pressure (DWP)
Show answer & explanationAnswer & explanation
Correct answer: A. 10 psig
For low-pressure systems, it is critical not to pressurize them beyond their design limits. The EPA recommends that a low-pressure system should not be pressurized above 10 psig for leak testing to prevent damage to the appliance, especially the rupture disc, or to avoid exceeding the relief valve setting.
Why the other options are wrong
- B. 10 inches of Hg vacuum is a vacuum, not a pressure. While 10 psig is correct, the combination makes this option incorrect.
- C. 0 psig is atmospheric pressure and insufficient for a useful leak test.
- D. The DWP for low-pressure systems is usually much higher than 10 psig, but exceeding 10 psig for a leak test risks damaging the system's relief devices which are set for lower pressures.
Low-Pressure System Leak Test Pressure
The maximum safe pressure to which a low-pressure refrigeration system should be pressurized with nitrogen for a leak test, to prevent damage to the system components.
- Applies to low-pressure systems.
- Uses nitrogen for leak testing.
- Maximum pressure: 10 psig.
- Prevents damage to rupture discs/relief valves.
Memory trick: Low pressure, nitrogen test, 10 psig max, put safety first!