rise
fall
be maintained constant
None of the above
第1题：
Low compressor head pressure in a refrigeration system can be caused by ___.
A.insufficient condenser cooling water
B.excessive condenser cooling water
C.air in the refrigeration system
D.excessive refrigerant in the system
第2题：
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
第3题：
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
第4题：
increase the flow of the cooling water through the condenser
adjust the high pressure cutout to maintain the desired pressure
open the hot gas bypass temporarily to reduce capacity
purge non-condensable gases to reduce the excess pressure
第5题：
insufficient lube oil circulating through the system
excessive circulation of lube oil through the system
insufficient refrigerant in the system
an overworked compressor
第6题：
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
第7题：
insufficient condenser cooling water
excessive condenser cooling water
air in the refrigeration system
excessive refrigerant in the system
第8题：
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
第9题：
flooding back
superheating
overflowing
recycling
第10题：
overheated compressor bearings
excess lube oil viscosity
carbon deposits on the compressor piston rings
wax crystals forming in the lubricant