If the head pressure of a reciprocating refrigeration compressor is excessive, （）.

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

The general purpose of a heat exchanger is to （）.

Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）

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

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

A salinity indicator is used to determine the （）.

Low compressor head pressure in a refrigeration system can be caused by（）.

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

Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.