A.Special tools are required for lapping or grinding
B.It is impossible to throttle flow with a butterfly valve
C.To close the valve, it is only necessary to turn the handle a quarter of a turn
D.The butterfly valve should never be used in a freshwater system
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A.closely observe the pump discharge temperature
B.close off the discharge valve, and watch for a rise in pressure
C.momentarily close off the suction valve, and watch for a rise in pressure
D.use a clamp on ammeter and compare the readings to past records
A.removing all but the frictional load during starting
B.relieving intercoolers of high temperature buildups
C.providing high starting torque in the drive motor
D.seating valve plates during compressor shutdown
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
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
最新試題
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
Low compressor head pressure in a refrigeration system can be caused by（）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
Which of the following statements is correct concerning heat transfer?（）
The usual symptoms of cavitation in a centrifugal pump is （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
A grease gun is generally used to lubricate a （）.
The general purpose of a heat exchanger is to （）.