EPA Section 608 Universal Certification ExamType II (High-Pressure Appliances)Medium
A technician is performing a major repair on a high-pressure appliance containing 18 pounds of R-407C. After recovering the refrigerant, the technician must evacuate the system. What vacuum level must be achieved before recharging the system?
- A1000 microns of mercury
- B0 psig
- C500 microns of mercury
- D25 inches of Hg vacuum
Show answer & explanationAnswer & explanation
Correct answer: C. 500 microns of mercury
For high-pressure appliances, after a major repair and recovery, the system must be evacuated to 500 microns of mercury or lower to ensure all non-condensables and moisture are removed, which is crucial for system efficiency and longevity.
Why the other options are wrong
- A. 1000 microns of mercury is insufficient; a deeper vacuum (500 microns) is required for high-pressure systems.
- B. 0 psig is atmospheric pressure, not a deep vacuum necessary for system dehydration.
- D. 25 inches of Hg vacuum is an insufficient vacuum level for proper dehydration of a high-pressure system after a major repair.
High-Pressure Appliance Evacuation Levels (Major Repair)
After a major repair on a high-pressure appliance, the system must be evacuated to a specific vacuum level to remove non-condensables and moisture.
- For high-pressure appliances, the required evacuation level after a major repair is 500 microns of mercury or lower.
- This deep vacuum ensures proper system dehydration.
- Insufficient evacuation can lead to system inefficiencies and component damage.
Memory trick: Vacuum to remove the VAPOR and AIR.