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
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相关考题
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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 -
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 -
单项选择题
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）
