单项选择题
Which of the listed statements is a characteristic of the liquid charged power element used with thermostatic expansion valves?（）
A.At the designed operating temperature, the liquid refrigerant charge has changed to a vapor
B.The liquid refrigerant tends to collect at the bellows or diaphragm and reduces the valve sensitivity
C.The sensing bulb is empty of liquid refrigerant charge at the designed operating temperature
D.The sensing bulb is never emptied of liquid refrigerant under normal operating conditions
相关考题
-
单项选择题
Differential pressures can be measured with the use of a （）.
A.diaphragm type gage
B.pressure transducer
C.manometer
D.All of the above -
单项选择题
The function of a centrifugal pump double volute casing is to （）.
A.reduce radial thrust to the impeller
B.double the liquid velocity through the pump when compared to a single volute
C.reduce hydraulic end thrust
D.provide the effect of multi-staging -
单项选择题
Dirt should not be allowed to contaminate a grease lubricant because the （）.
A.dirt will cause corrosion of bearing
B.bearings will leak oil excessively
C.dirt is very abrasive when mixed with grease
D.grease will become inflammable
