If the suction pressure at the refrigeration compressor is b

Excessive oil foaming in the crankcase of a refrigeration compressor is most likely to occur when the compressor

A.has run continuously for a long period

B.suction pressure is below normal

C.oil level is below normal

D.starts after a long idle period

If the suction pressure at the refrigeration compressor is below normal, the cause can be

A.refrigerant overcharge

B.overfeeding by the expansion valve

C.a restricted suction strainer

D.due to short cycling of the compress

If the refrigeration compressor crankcase is sweating, the cause may be due to

A.a shortage of refrigerant

B.the compressor running continuously

C.liquid refrigerant returning to the compressor

D.the compressor short cycling on the high pressure cutout

The sensing line for the low pressure cutout switch to a refrigeration system is located ______.

A.in the chill box(冰箱)

B.before the receiver

C.on the suction side of the compressor

D.on the discharge side of the compressor

In the refrigeration system, a shortage of refrigerant is indicated by

A.the compressor short cycling on high pressure cut out switch

B.high suction pressure

C.high head pressure

D.bubbles in the sight glass

Sweating of the refrigeration system compressor crankcase is caused by_______ .

A.too much superheat

B.insufficient superheat

C.suction pressure too low

D.excessive refrigerant returning to the compressor

When adding oil to a refrigeration system, precautions must be taken to ensure that

A.the compressor suction pressure is not too high

B.all air is purged from the pump and charging fittings

C.the high pressure cutout switch is held open to prevent accidental starting

D.the condenser is completely shutdown first

If the suction pressure for an operating refrigeration compressor is below normal, the cause may be ______.

A.an excess of liquid refrigerant

B.the expansion valve overfeeding

C.a fouled compressor suction strainer

D.the compressor short cycling