A.scaled
B.informed
C.leaky
D.deformed
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A.sealed
B.cracked
C.shape changed
D.deformed
A.deformed
B.rusted
C.cracked
D.scaled
A.in series
B.in parallel
C.either A or B
D.None of the above is tree
Which of the following pumps are self-priming, and can deal with liquid from a level below the pump: （）
(1)reciprocating
(2)vane
(3)gear
A.（1）only
B.（1）and（2）
C.（2）and（3）
D.（1），（2）and（3）
Which of the following will be the advantage of a centrifugal pump as compared with a reciprocating pump?（）
(1) Its discharge is continuous
(2) It has no internal valves
(3) Upon accidental closing of discharge valve, excessive pressure will not build up
A.（1），（2）
B.（2），（3）
C.（1），（2），（3）
D.（2）only
最新試題
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
Which of the listed pumps is NOT a positive displacement pump?（）
The output volume of a positive fixed displacement pump can be changed only by （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
The general purpose of a heat exchanger is to （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
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?（）