单项选择题
A.to fill 2 tanks at the same time B.to use pump at a higher pressure C.to return liquid to suction side if discharge valve is closed D.All of the above are true
A （） pump is that where the volume of the pump chamber ...
单项选择题A （） pump is that where the volume of the pump chamber is alternately increased to draw the liquid in and then decreased to force the liquid out.
A.injector B.positive displacement C.centrifugal D.centripetal
A reciprocating pump belongs to （） according to its wor...
单项选择题A reciprocating pump belongs to （） according to its working principle.
A.injector pumps B.positive displacement pumps C.centrifugal pump D.centripetal pumps
Shaft sealing in a centrifugal pump can be effected by ...
单项选择题Shaft sealing in a centrifugal pump can be effected by （）.
A.the mechanical seal B.packed stuffing boxes C.either A or B D.neither A nor B
