单项选择题
Which of the following statements concerning the water tube and fire tube boilers is not true?（）
A.natural circulation of the water in the water tube boiler is better than that in the fire tube boiler
B.for the same output the water tube boiler will carry less mass of water compared with the fire tube boiler
C.the water tube boiler will cost shorter time for steam raising
D.the water tube boiler require lower skill in operating and maintaining
相关考题
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单项选择题
Which one of following statement is not true concerning the suitable sites of the direct acting relief valve and the pilot operated relieve valve?（）
A.the direct acting relief valve is used for controlling lower flows and pressure
B.the pilot operated relief valve is used for controlling higher flows and pressure
C.the pilot operated relief valve is used for controlling lower flows and pressure
D.the controlling accuracy of direct acting relief valve is worse than that of the pilot operated relief valve -
单项选择题
In heavy marine engine the practice is to drive the engine on（）which has previously been stored in starting air reservoirs.
A.electric motor
B.hydraulic motor
C.compressed air
D.turning gear -
单项选择题
The water level of an exhaust gas boiler which is independent of the auxiliary boiler and just as the extra heating surface of it （）
A.will be modulated in proportion
B.will be modulated in proportion and integral
C.will be modulated in proportion and differential
D.will not be modulated at all
