单项选择题

Excessive air leakage into the suction side of a centrifugal pump would be indicated by which of the following operational problems?（）

A.The pump delivers full capacity when started, but gradually slackens off toan abnormally low flow
B.The pump packing gland overheats after short operating periods
C.The motor over-current protective device continually shuts the pump down
D.Pounding noises can be heard at the pump suction chest

<上一题目录下一题>

热门试题

单项选择题Increasing the speed of a centrifugal pump will result in an increase in its capacity Another means of increasing the capacity of a centrifugal pump is to increase the （）.

A.diameter of the discharge piping, with all other factors remaining the same
B.diameter of the suction piping, with all other factors remaining the same
C.width of the impeller only
D.diameter of the impeller

单项选择题If the discharge valves on a refrigeration compressor are leaking badly, the compressor should （）.

A.run continuously
B.not start
C.have high discharge pressure
D.short cycle on the high pressure switch

单项选择题Which of the following terms could be applied to the simple definition the energy of motion?（）

A.Electrical energy
B.Thermal energy
C.Potential energy
D.Kinetic energy

单项选择题The delivery rate of an axial-piston hydraulic pump is controlled by varying the position of the （）.

A.sliding block
B.pintle
C.reaction ring
D.tilting box or swash plate

单项选择题Badly leaking refrigeration compressor discharge valves will cause（）.

A.overfeeding of the expansion valve
B.damage to the condenser
C.constant running of the compressor
D.flooding of the receiver