What is the main risk of energizing a hermetic compressor while the system is in a deep vacuum?
Safety · EPA 608 Type II. The correct answer, and the reasoning behind it.
Hermetic compressors under vacuum and other high-pressure hazards.
The question
What is the main risk of energizing a hermetic compressor while the system is in a deep vacuum?
- The oil will freeze
- The refrigerant will decompose into acids and sludge
- The suction line will collapse
- Breakdown of the motor winding insulationCorrect answer
Why “Breakdown of the motor winding insulation” is correct
With almost no gas around the windings, the insulation can break down and the motor can short or arc. That can burn out the motor of a hermetic compressor, which sits inside the sealed shell.
Source: EPA: Test Topics
Why the other answers are wrong
- The oil will freeze — Oil does not freeze from running in a vacuum.
- The refrigerant will decompose into acids and sludge — There is almost no refrigerant left in a deep vacuum to decompose.
- The suction line will collapse — Copper suction lines do not collapse under vacuum.
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