單項選擇題

Fusible plugs are installed in fire-tube boilers to （）.

A.provide a means of draining the boiler
B.warn the engineer of low water level
C.cool the crown sheet at high firing rates
D.open the burners electrical firing circuits

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單項選擇題

In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low alloy steels because （）.

A.the beveled edges of the intake valves provide for serf-centering during seating
B.intake valves utilize stellite-coated valve seat inserts which reduce wear
C.the volume of air passing through intake valves is less than the volume of air passing through exhaust valves
D.intake valves are less affected to the corrosive action of exhaust gases

單項選擇題

What preventative maintenance should be done frequently to diesel engine starting air receivers?（）

A.Drain the accumulated moisture
B.Test the relief valves
C.Watch the temperature to prevent fluctuations in pressure
D.Clean the interior to remove oil and foreign matter