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
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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
A.weight designation
B.viscosity index
C.pour point
D.thermal change value
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When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
Low compressor head pressure in a refrigeration system can be caused by（）.
One cause of high head pressure occurring in a refrigeration system can be （）.
When the steering gear is in operation, you should （）.
A grease gun is generally used to lubricate a （）.
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.