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

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

Which of the following statements is correct concerning heat transfer?（）

The major source of chemical contaminants in hydraulic fluid is （）.

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

The rate of heat transfer from a hot region to a cold region is affected most by the （）.

An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.

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

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

The output volume of a positive fixed displacement pump can be changed only by （）.