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單項(xiàng)選擇題

The suction - force principle of operation is a typical characteristic of （）.

A.centrifugal pumps
B.jet pumps
C.propeller pumps
D.reciprocating pumps

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單項(xiàng)選擇題

Air leakage between the shaft and stuffing box packing in a centrifugal pump is prevented by （）.

A.a compressed packing gland
B.lantern tings between the packing rings
C.a liquid seal
D.the stuffing box gland

單項(xiàng)選擇題

Tube leaks in the distillate cooler of a two stage flash evaporator will result in （）.

A.loss of second stage vacuum
B.contamination of the distillate
C.lower feed inlet temperature
D.contamination of the second stage condenser