单项选择题
In a refrigeration system, foaming of the crankcase oil may cause the ().
A.expansion valve to overfeed
B.compressor to knock
C.water regulating valve to fail
D.crankcase drains to plug
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单项选择题
Foaming of the oil in a refrigeration compressor crankcase is caused by ().
A.refrigerant boiling out of solution from the lube oil
B.liquid refrigerant flooding the compressor and system
C.lube oil viscosity being reduced by refrigerant dilution
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Which of the listed characteristics can be applied to R- 12 vapor?()
A.It is corrosive
B.It is odorless
C.It is visible as h blue fog
D.It has a distinctive taste
