单项选择题
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 centr...
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
The pipe friction and the resistance will （） as a resul...
单项选择题The pipe friction and the resistance will （） as a result of an increase in the amount of fluid flowing through the system.
A.reduce B.rise C.raise D.fall
Air chambers are usually fitted to reciprocating pumps ...
单项选择题Air chambers are usually fitted to reciprocating pumps in order to （）.
A.increase discharge pressure B.increase suction vacuum C.develop pulsation flow D.keep a steady rate of flow
