Why does pulling a deep vacuum help remove water from a system?
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
Why does pulling a deep vacuum help remove water from a system?
- It turns water into a non-condensable gas
- It freezes the water so it can be drained out later
- It pushes water into the compressor oil
- It lowers water's boiling point so it boils offCorrect answer
Why “It lowers water's boiling point so it boils off” is correct
The lower the pressure, the lower the temperature at which water boils. In a deep vacuum, moisture inside the system boils off at ordinary temperatures and the vacuum pump draws out the vapor.
Source: EPA: Test Topics
Why the other answers are wrong
- It turns water into a non-condensable gas — Water vapor is condensable; it is removed as vapor, not changed into air.
- It freezes the water so it can be drained out later — Freezing would trap water rather than remove it; good practice avoids it.
- It pushes water into the compressor oil — Moving water into the oil would contaminate it, not remove it.
Practice more of this
More EPA 608 Core practice questions, or see every EPA 608 practice test.
Unofficial, not affiliated with the EPA or any EPA-approved certifying organization. Questions are original practice written from public EPA material, not real exam questions.