A.two or more impellers housed together in one casing and mounted on a single shaft
B.a single stepped impeller mounted in a progressively staged casing
C.a large radial clearance between the impeller and casing to prevent overheating due to
D.an increase in the discharge velocity of the liquid with a corresponding decrease in pressure through the stages
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A.add refrigerant to the system
B.adjust the thermal expansion valve to the proper setting
C.adjust the float valve to the proper holding pressure
D.open the hand expansion valve
A.a stuck solenoid valve
B.a shortage of refrigerant
C.too much oil in circulation
D.too much superheat
A.trick-wheel
B.follow-up control
C.six-way valve
D.Rapson slide
A.stress
B.strain
C.shear strength
D.ultimate tensile strength
A.increase discharge pressure
B.decrease pump capacity
C.decrease pump cavitation
D.decrease reaction ring clearance
最新試題
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
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?（）
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
Which of the listed pumps is NOT a positive displacement pump?（）
The general purpose of a heat exchanger is to （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
When the steering gear is in operation, you should （）.