Which instrument is used to confirm that a deep vacuum has been reached during dehydration?
Dehydration and evacuation · EPA 608 Core. The correct answer, and the reasoning behind it.
Evacuating to remove air and moisture at the end of service.
The question
Which instrument is used to confirm that a deep vacuum has been reached during dehydration?
- A sight glass
- A refrigerant scale
- A micron gaugeCorrect answer
- An ammeter
Why “A micron gauge” is correct
A micron gauge reads very low absolute pressures, far below what a compound gauge can show accurately. It tells the technician when the vacuum is deep enough and whether pressure rises after the pump is isolated.
Source: EPA: Test Topics
Why the other answers are wrong
- A sight glass — A sight glass shows liquid flow during operation.
- A refrigerant scale — A scale weighs refrigerant; it does not measure vacuum.
- An ammeter — An ammeter measures electrical current.
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