If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.

单项选择题A salinity indicator is used to determine the （）.

A.cause of salt contamination
B.location of salt water contamination
C.chemical makeup of feed-water
D.level of alkalinity in condensate

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

A.refrigerant overcharge
B.overfeeding by the expansion valve
C.a restricted suction strainer
D.due to short cycling of the compressor

单项选择题If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.

A.capacity will increase
B.capacity will decrease
C.suction pressure will increase
D.suction pressure will decrease

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

A.hydraulic
B.electric
C.steam
D.diesel

单项选择题When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.

A.increase the amount of cooling water to the condenser
B.decrease the amount of cooling water to the condenser
C.add more refrigerant to the system
D.remove some refrigerant from the system