单项选择题
A.increase discharge pressure B.increase suction vacuum C.develop pulsation flow D.keep a steady rate of flow
Some pumps use packing as sealing glandThe gland should...
单项选择题Some pumps use packing as sealing glandThe gland should be （）.
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
Which of the following pumps is used where a relatively...
单项选择题Which of the following pumps is used where a relatively high pressure and small capacity are required?（）
A.Volute pump B.Diffuser pump C.Regenerative pump D.All of the above
The （） pump discharges a nearly constant amount of liqu...
单项选择题The （） pump discharges a nearly constant amount of liquid regardless of pressure.
A.mixed-flow B.axial-flow C.centrifugal D.displacement
