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


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1.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

2.單項(xiàng)選擇題The color of the flame on a halide torch without any refrigerant present is ().

A.blue
B.green
C.orange
D.purple

3.單項(xiàng)選擇題The color of the flame on a halide torch without any refrigerant present is ().

A.blue
B.green
C.orange
D.purple

4.單項(xiàng)選擇題If a refrigeration compressor is running continuously without lowering temperature as normal in the refrigerator, the trouble may be ().

A.excessive condenser cooling water
B.warm food in the refrigerator
C.a shortage of refrigerant
D.s shortage of compressor oil

5.單項(xiàng)選擇題Thermostatic expansion valve are ().

A.either all the way open or all the way closed
B.normally open
C.throttled depending on load
D.controlled by suction pressure

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If the suction pressure at the refrigeration compressor is below normal, the cause can be().

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An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by ().

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The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its ().

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On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is ().

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One cause of high head pressure occurring in a refrigeration system can be ().

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A salinity indicator is used to determine the ().

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The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?()

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Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?()

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Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by ().

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If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will ().

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