單項(xiàng)選擇題

Which of the listed statements is correct concerning the starting of centrifugal pumps?（）

A.They should always be started with the discharge valve closed
B.They should always be started with the discharge valve opened
C.A priming pump is always required to flood the impeller suction
D.They should always be started with the sealing line valves closed

你可能感興趣的試題

單項(xiàng)選擇題

Excessive oil foaming in the crankcase of a refrigeration compressor at start up can cause（）.

A.compressor damage from improper lubrication
B.refrigerant absorption by the lubricant
C.increased viscosity in the lubricant
D.carbon deposit on the compressor suction valves

單項(xiàng)選擇題

Which of the valves listed is NOT considered to be a hydraulic system directional control valve?（）

A.Spring-centered valve
B.Unloading valve
C.Three-position valve
D.Two-position valve

97免费在线观看视频,亚洲综合自拍网,黄色毛片免费观看,热久久综合网,免费看日产一区二区三区 狠狠操av,久久久涩涩涩,在线精品免费视频,人人插天天干,久久91精品国产91久久

Which of the listed statements is correct concerning the starting of centrifugal pumps?（）

你可能感興趣的試題

Excessive oil foaming in the crankcase of a refrigeration compressor at start up can cause（）.

Which of the valves listed is NOT considered to be a hydraulic system directional control valve?（）

97免费在线观看视频,亚洲综合自拍网,黄色毛片免费观看,热久久综合网,免费看日产一区二区三区狠狠操av,久久久涩涩涩,在线精品免费视频,人人插天天干,久久91精品国产91久久