A.loose expansion valve control bulb
B.low differential setting on the H-Pcutout
C.blown fuse in the motor circuit
D.faulty suction pressure regulator
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A.prevent an internal explosion in the pump when it is overheated
B.enable a visual inspection of the pump while it is running
C.insure a proper alignment of the pump coupling to the driver
D.accommodate for friction between the impeller and the easing
A.explosive range
B.flash point
C.ignition temperature
D.combustion temperature
A.the pressure regulating valve is not closing
B.an excessive lack of refrigerant in the system
C.badly leaking discharge valves
D.worn piston rings
A.Both are higher than normal burning temperatures
B.The flash point is always higher
C.The ignition temperature is always higher
D.They are not necessarily related
A.tend to twist about its long axis
B.expand in length and in diameter
C.contract in length and expand in diameter
D.flex at right angles to the applied pressure
最新試題
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
A pressure drop through the refrigerant liquid line may cause （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
Which of the listed pumps is NOT a positive displacement pump?（）
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
The general purpose of a heat exchanger is to （）.
Which of the following statements is correct concerning heat transfer?（）