单项选择题
A pump is defined as device that（）
A.produces pressure
B.imparts energy to a fluid to move it from level ‘A’ to level ‘B’
C.creates a vacuum to move a liquid in all installation
D.is to develop a pressure differential
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相关考题
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单项选择题
A distorted furnace in a fire-tube auxiliary boiler may be the result of （）
A.firing for extended periods in the low fire mode
B.overheating, due to waterside deposits
C.varying the water level above the crown sheet
D.carrying excessive alkalinity in the boiler water -
单项选择题
Fins are installed on the fireside of water-tubes used in waste boiler to（）
A.decrease the velocity of gases flowing past the tubes
B.increase the rate of heat transfer
C.reduce accumulations carbon deposits
D.direct the flow of gases -
单项选择题
A smoking burner with a pulsating flame in auxiliary boiler, is an indication that the（）
A.fuel oil supply temperature is normal
B.burner electrode is incorrectly positioned
C.fuel／air ratio is incorrect
D.ignition current is too low
