A.A gate valve
B.A globe valve
C.Any check valve
D.Any needle valve
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A.a shortage of compressor oil
B.warm food in the refrigerator
C.excessive condenser cooling water
D.a shortage of refrigerant
A.molecular fluid vibration
B.energy losses
C.wide pressure variations
D.mechanical damage to control valves
A.Keeps the refrigerated space cooler
B.Reduces the efficiency of the plant
C.Takes the load off the compressor
D.Has no affect on the system
A.proportional band
B.the error signal
C.the reset signal
D.feedback
A.Dehydrators must be used continuously in a refrigeration system
B.A 25 ton refrigeration system has the same cooling effect as melting 25 tons of ice in 24 hours
C.A thermostatic expansion valve is used to control refrigerated space temperature
D.The liquid receiver functions to collect and remove non- condensable gases
最新試題
A salinity indicator is used to determine the （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
A pressure drop through the refrigerant liquid line may cause （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
A grease gun is generally used to lubricate a （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
The general purpose of a heat exchanger is to （）.