单项选择题For many years marine centrifuges were designed for () operation, that is the machines were run for a period during which solids accumulated in the bowlThe machine was stopped when the accumulated solids began to impair its performance.

A.purifying
B.batch
C.long period
D.temporary


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1.单项选择题When a clarifier is running the impurities and water collect at the bowl ().

A.center
B.periphery
C.inlet
D.upper parts

2.单项选择题A centrifuge arranged to separate impurities and small amounts of water from oil is known as ().

A.an oily water separator
B.a purifier
C.a centrifugal compressor
D.a clarifier

3.单项选择题A centrifuge arranged to separate two liquids is known as ().

A.an oily water separator
B.a purifier
C.a centrifugal compressor
D.a clarifier

4.单项选择题Emulsification of oil will occur when mixed with ().

A.air
B.black oil
C.water
D.ice cream

6.单项选择题Oil water separators are used to ensure that ships dont discharge oil when pumping out ().

A.ballast water
B.boiler water
C.bilge water
D.sewage water

7.单项选择题()are used to ensure that ships don’t discharge oil when pumping out oily water from any oil contaminated space.

A.Boiler
B.Incinerator
C.Oily water separator
D.Sewage treatment unit

8.单项选择题High-speed rotation in a centrifugal purifier can produce a force () the force of gravity.

A.many thousand times larger than
B.the same as
C.many thousand times smaller
D.none of the above

10.单项选择题

Which of the following may hardness of the boiler water cause?()
(1) scale formation
(2) tube failure
(3) corrosion

A.(1)and(2)
B.(1)and(3)
C.(2)and(3)
D.(1),(2)and(3)