A.condensate
B.a small amount of make-up feed
C.A and B
D.None of the above
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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
A.kg
B.MPa
C.mH20
D.None of the above
Which of the following are components of a mechanical seal? ()
(1) stationary ring
(2) rotational ring
(3) packing
(4)spring
A.(1), (2) and (3)
B.(1), (2) and (4)
C.(2), (3) and (4)
D.None of the above
最新试题
The usual symptoms of cavitation in a centrifugal pump is ().
Low compressor head pressure in a refrigeration system can be caused by().
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its ().
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by ().
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be ().
The major source of chemical contaminants in hydraulic fluid is ().
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by ().
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will ().
A salinity indicator is used to determine the ().
The control mode in which the final control element is moved from one of two flexed positions to the other is known as ().