A.maintain radial alignment between the pump impeller and casing
B.absorb all impeller shaft end thrust
C.prevent water leakage to the atmosphere
D.prevent wear of the pump casing and/or impeller
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A.psychrometer
B.salinometer
C.anemometer
D.sphygmomanometer
A.A large change of viscosity occurs with a minor change in temperature
B.No change in viscosity occurs with any change in temperature
C.Very little change in viscosity occurs with a significant change in temperature
D.The viscosity of the oil increases with an increase in temperature
A.pump would be very noisy
B.pump would vibrate excessively
C.pump would develop insufficient flow
D.stuffing box would leak excessively
A.gravity and feed oil cups
B.grease cups
C.hand during installation
D.leakage through the stuffing box
A.a needle gun
B.soap and water
C.a wire brush
D.a chipping hammer
最新試題
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
Which of the listed pumps is NOT a positive displacement pump?（）
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
One cause of high head pressure occurring in a refrigeration system can be （）.
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
A grease gun is generally used to lubricate a （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）