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
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）
A grease gun is generally used to lubricate a （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
Which of the listed pumps is NOT a positive displacement pump?（）
Low compressor head pressure in a refrigeration system can be caused by（）.