EPA Section 608 Universal Certification ExamType II (High-Pressure Appliances)Hard
A technician is evacuating a high-pressure system after a major component replacement. To ensure proper dehydration of the system, what is the recommended final vacuum level?
- A29.9 inches Hg vacuum
- B10 inches Hg vacuum
- C0 psig
- D500 microns
Show answer & explanationAnswer & explanation
Correct answer: D. 500 microns
Proper dehydration requires pulling a deep vacuum, typically measured in microns. A vacuum of 500 microns (or 29.92 inches Hg vacuum) or lower is generally recommended to ensure all moisture has been boiled off and removed from the system.
Why the other options are wrong
- A. 29.9 inches Hg vacuum is close to a perfect vacuum, but microns provide a more precise and accurate measurement for dehydration.
- B. 10 inches Hg vacuum is a recovery level, not a dehydration level.
- C. 0 psig is gauge pressure, not a vacuum level sufficient for dehydration.
System Dehydration Vacuum Level
Dehydration of an HVAC/R system involves removing moisture by pulling a very deep vacuum, typically measured in microns, to lower the boiling point of water and facilitate its removal.
- Moisture is highly detrimental to system operation and longevity.
- A deep vacuum (e.g., 500 microns) ensures water boils at ambient temperatures.
- A micron gauge is essential for accurate measurement.
Memory trick: Microns for moisture, a deep, deep pull, keeps the system clean, never dull.