單項(xiàng)選擇題Hydraulic machinery failures are commonly caused by misalignment of the system components and by （）.

A.hydraulic fluid contamination
B.excessive fluid friction
C.turbulent fluid flow
D.fluid pressure surges


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1.單項(xiàng)選擇題Air compressor receivers should be “blown down” at least （）.

A.yearly
B.quarterly
C.monthly
D.daily

2.單項(xiàng)選擇題A thermostatic expansion valve is properly controlling evaporator superheatAdjusting this valve to lower the superheat will result in a/an （）.

A.evaporator pressure decrease
B.evaporator coil over-feed
C.evaporator capacity increase
D.expansion valve diaphragm rupture

3.單項(xiàng)選擇題It is possible to mount a double suction centrifugal pump impeller with the vanes facing in the wrong directionThis would cause the pump （）.

A.head capacity to improve
B.discharge to be reversed
C.efficiency to decrease
D.slippage to decrease

4.單項(xiàng)選擇題Water allowed to accumulate in the hydraulic system oil will cause an oxidation process producing by- products which are normally （）.

A.gums, acids, and varnishes
B.removed by cellulose type filters
C.neutralized by oil additives
D.not removed by absorbent filters

5.單項(xiàng)選擇題If an anchor windlass has been idle for some time, you should （）.

A.repack all valve stems
B.lubricate it prior to use
C.replace the foundation bolts
D.balance the warping heads