單項(xiàng)選擇題When there is a flame failure in an automatically fired auxiliary boiler, the （）.

A.air supply is shut off
B.fuel supply is shut off
C.water supply is shut off
D.safety valve lifts


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1.單項(xiàng)選擇題If the feed pump for an auxiliary boiler fails to deliver the feed water to the boiler, the cause maybe （）.

A.high steam pressure in the boiler
B.abnormally high feed water temperature
C.abnormally high boiler water temperature
D.steam demand exceeding feed pump capacity

2.單項(xiàng)選擇題Which of the following conditions can cause above normal air temperature to develop in the intake manifold of a four-stroke/cycle turbo-charged diesel engine?（）

A.Clogged air intake falters
B.Piston blow-by
C.A defective after-cooler
D.Faulty exhaust valves

4.單項(xiàng)選擇題The crankcase of many diesel engines are kept under a slight vacuum by the （）.

A.scavenging action of the piston
B.piston type vacuum pump taking suction off a differential manometer
C.gland exhausting manometer
D.crankcase exhaust fan

5.單項(xiàng)選擇題Fins are installed on the generating tube surfaces in waste heat boilers to （）.

A.prevent soot fires in the exhaust system
B.prevent exhaust gas erosion of the tubes
C.increase the velocity of exhaust gas flow
D.increase the rate of heat transfer