A.water seal pipe is plugged
B.pump is not primed
C.seal ring is improperly located
D.impeller is flooded
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A.Close radial clearance between impeller hub and casing
B.Low rotational speed of impeller
C.Removable end plate
D.Replaceable impeller and casing wearing rings
A.fill the unit with saltwater
B.fill the unit with de-scaling compound
C.completely drain the unit
D.tightly seal the unit to exclude air
A.dischargeendbeingsmallerthanthesuctionend
B.smallsizeofimpeller
C.lackofmovingparts
D.easeatwhichthewearingringsmaybechanged
A.fusion
B.vaporization
C.sublimation
D.condensation
A.Overcoming sliding friction
B.Overcoming rolling friction
C.Overcoming fluid friction
D.Overcoming oil wedge friction
最新試題
Thermostatic expansion valves can be adjusted for （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
A pressure drop through the refrigerant liquid line may cause （）.
Low compressor head pressure in a refrigeration system can be caused by（）.
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.