Which of the valves listed is NOT considered to be a hydraulic system directional control valve?（）

单项选择题Which of the listed refrigeration system components keeps the refrigerant circulating through the system?（）

A.Expansion valve
B.Condenser
C.Evaporator
D.Compressor

单项选择题Which of the listed components is considered to separate the high pressure side of a refrigeration cycle from the low pressure side of the cycle?（）

A.The condenser and the expansion valve
B.The king valve and the solenoid valve
C.The compressor and the expansion valve
D.The condenser and the solenoid valve

单项选择题A compound gage is used to measure （）.

A.temperature and pressure
B.humidity and temperature
C.pressure and vacuum
D.pressure and humidity

单项选择题A centrifugal pump attempting to develop flow against a closed discharge valve has a an （）.

A.capacity of 0%
B.efficiency of 100%
C.internal slippage of 0%
D.shut off horsepower rating of 100%

单项选择题Condensate formed within the first-effect tube nest of a double-effect,low pressure evaporator, is removed by a （）.

A.series of baffles
B.crossover pipe
C.condensate separator
D.drain pump