A.reduce
B.rise
C.raise
D.fall
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A.increase discharge pressure
B.increase suction vacuum
C.develop pulsation flow
D.keep a steady rate of flow
A.slack enough to allow slight leakage of fluid
B.slightly clocked
C.brought up tight so as not to allow any leakage
D.fitted with a relief valve
A.Volute pump
B.Diffuser pump
C.Regenerative pump
D.All of the above
A.mixed-flow
B.axial-flow
C.centrifugal
D.displacement
Which of the following operating features do displacement pumps bear if they are working under no-cavitation condition?（）
(1) output is almost directly proportional to speed
(2) they are self-priming
(3) they will develop a discharged pressure equal to the resistance to be overcome, irrespective of speed
A.（1）and（2）
B.（2）and（3）
C.（1）and（3）
D.（1），（2）and（3）
最新試題
Thermostatic expansion valves can be adjusted for （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
A salinity indicator is used to determine the （）.
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 （）.
If you are given the job of adding hydraulic fluid to a mooring winch, and are not certain as to the type of fluid to use, you should （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
Which of the listed pumps is NOT a positive displacement pump?（）