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
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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
A.holding the discharge valve open
B.relieving the intercooler pressure to the atmosphere
C.using an enlarged, permanently opened clearance expansion space
D.a pre-charged accumulator
最新試題
Which of the following statements is correct concerning heat transfer?（）
The general purpose of a heat exchanger is to （）.
A salinity indicator is used to determine the （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
A pressure drop through the refrigerant liquid line may cause （）.
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
The major source of chemical contaminants in hydraulic fluid is （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）