A.oxygen in the water
B.poor boiler design
C.density too high
D.excessive steam demand
您可能感兴趣的试卷
你可能感兴趣的试题
A.yellowish flame
B.golden yellow flame
C.white flame
D.brilliant white flame
A.condensate
B.a small amount of make-up feed
C.A and B
D.None of the above
A.yellowish flame
B.golden yellow flame
C.white flame
D.brilliant white flame
A.low water level
B.low oil pressure
C.excessively high fuel pressure
D.an improper air/fuel ratio
A.Reciprocating pump
B.Screw pump
C.Diffuser pump
D.Water-ring pump
A.discharge is continuous
B.it has no internal valves
C.upon accidental closing of discharge valve, excessive pressure will not build up
D.all of the above are true
A.between the suction and discharge
B.below the liquid supply
C.above the liquid supply
D.any of the above
Which of the following pumps are self-priming, and can deal with liquid from a level below the pump? ()
(1) reciprocating
(2) vane
(3) gear
A.(1)only
B.(1)and(2)
C.(1),(2)and(3)
D.(2)and(3)
Which of the following pumps are self-priming, and can deal with liquid from a level below the pump? ()
(1) reciprocating
(2) rotary
(3) centrifugal
A.(1)only
B.(1)and(2)
C.(1),(2)and(3)
D.(2)and(3)
A.increased;decreased
B.decreased;increased
C.decreased;decreased
D.increased;increased
最新试题
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by ().
The control mode in which the final control element is moved from one of two flexed positions to the other is known as ().
The usual symptoms of cavitation in a centrifugal pump is ().
The major source of chemical contaminants in hydraulic fluid is ().
An excessive charge of refrigerant in an air-cooled refrigeration system can cause ().
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?()
The general purpose of a heat exchanger is to ().
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by ().
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should ().
If the suction pressure at the refrigeration compressor is below normal, the cause can be().