A.rise when the steam pressure is increased
B.remain constant as long as the feed pump operates
C.fall when the steam pressure is decreased
D.vary as the steam demand changes
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A.to raise water level
B.only while making steam
C.to remove scum
D.when fire are secured
A.drop as the boiler warms up
B.rise as the boiler warms up
C.remain unchanged until the boiler is hot enough
D.rise and fall with the steam demand
A.filled with water
B.purged
C.cleared of air
D.None of the above is true
A.Safety valves
B.Water tubes
C.Steam stop valves
D.Blow down valves
A.water-tube
B.fire-tube
C.exhaust gas
D.None of the above is true
最新試題
A grease gun is generally used to lubricate a （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
Which of the following statements is correct concerning heat transfer?（）
One cause of high head pressure occurring in a refrigeration system can be （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.