轮机英语船舶辅助机械章节练习(2018.01.13)

单项选择题
When a boiler is operating, the water level in the gauge glass reads （） when the boiler is shut down.
A.lower than
B.higher than
C.as much as
D.the same as
单项选择题
The type of gauge most commonly used to measure pressure is the （）.
A.bimetallic type
B.diaphragm type
C.bourdon tube type
D.resistance-temperature type
单项选择题
The internal part of boiler should be cleaned by yard if found （）.
A.scaled
B.worn
C.deformed
D.rested
单项选择题
As for a oil-fired boiler too much air would indicated by （）.
A.yellowish flame
B.golden yellow flame
C.milky flame
D.brilliant white flame
单项选择题
Which of the problems listed represents the major difficulty encountered with thermal expansion valve operation?（）
A.Lube oil passing through the system
B.Moisture or foreign matter collecting at the valve seat and orifice
C.Variable spring tension caused by the changing temperature
D.Frost on the liquid line
单项选择题
A refrigeration unit will tend to short cycle when operating （）.
A.under heavy loads
B.during hot gas defrost
C.under light loads
D.during starting conditions
单项选择题
Increasing the speed of a centrifugal pump will result in an increase in its capacity Another means of increasing the capacity of a centrifugal pump is to increase the （）.
A.diameter of the discharge piping, with all other factors remaining the same
B.diameter of the suction piping, with all other factors remaining the same
C.width of the impeller only
D.diameter of the impeller
单项选择题
The usual symptoms of cavitation in a centrifugal pump is （）.
A.noise and vibration
B.an increase in discharge pressure
C.an increase in suction pressure
D.lifting of the relief valve
单项选择题
Which of the following statements is correct concerning the “flash point ” of a liquid?（）
A.It is lower than the ignition temperature
B.It is the temperature at which a substance will spontaneously ignite
C.It is the temperature at which a substance, when ignited, will continue to bum
D.It is the temperature at which the released vapors will fall within the explosive range
单项选择题
Which of the following statements is correct regarding an oil with a high viscosity index?（）
A.A large change of viscosity occurs with a minor change in temperature
B.No change in viscosity occurs with any change in temperature
C.Very little change in viscosity occurs with a significant change in temperature
D.The viscosity of the oil increases with an increase in temperature