EPA Section 608 Universal Certification ExamType II (High-Pressure Appliances)Hard
A technician is verifying the dehydration of a high-pressure appliance after a major repair. After pulling a vacuum, the micron gauge shows 550 microns. The technician closes the valve to the vacuum pump and monitors the system. After 15 minutes, the micron gauge reads 600 microns. What does this indicate?
- AThe vacuum pump is faulty and needs to be replaced.
- BThe system is properly dehydrated and ready for recharge.
- CA slight increase in pressure is normal and can be ignored.
- DThere is still moisture in the system that is boiling off.
Show answer & explanationAnswer & explanation
Correct answer: D. There is still moisture in the system that is boiling off.
A rise in micron gauge reading after isolating the vacuum pump indicates the presence of moisture or a leak. Since the system was evacuated to near the target (500 microns), a slight rise suggests that residual moisture is still boiling off, increasing the system pressure. The system requires further evacuation.
Why the other options are wrong
- A. While a faulty pump could be a cause of not reaching vacuum, the rise *after* isolation points to system integrity issues (moisture or leak), not necessarily the pump itself at this stage.
- B. A pressure rise indicates either moisture or a leak, meaning it's not properly dehydrated.
- C. Any pressure rise after isolation, especially above the target, is not normal and indicates an issue.
System Dehydration Verification (Pressure Rise)
After evacuating a system, monitoring the micron gauge for a pressure rise after isolating the vacuum pump helps verify complete dehydration and leak-tightness.
- A stable vacuum (no rise) indicates proper dehydration and no leaks.
- A gradual, slight rise indicates residual moisture boiling off.
- A rapid or significant rise indicates a leak in the system.
- The system is not ready for recharge if pressure rises after isolation.
Memory trick: Micron RISE: MOISTURE or LEAK, don't be a freak!