單項選擇題One engine manufacturer recommends heavy fuel oil should not be heated above 80℃ to 95℃ (176 ℉ TO 203℉) before purificationThis upper limit should be observed to ensure against（）

A.flattening of the bowl neoprene O-rings
B.operation within the explosive rang of the fuel
C.excessive purifier operating pressures
D.excessive oil viscosity


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1.單項選擇題Which of the substances listed is satisfactorily removed from the fuel by a centrifugal oil purifier?（）

A.Carbon particles
B.Lube oil
C.Gasoline
D.Diesel fuel

2.單項選擇題Which of the following problems will occur if a disk-type centrifugal lube oil purifier is not properly primed prior to admitting oil flow to the bowl?（）

A.Contamination of the lube oil by emulsification will result
B.The lube oil will not be subjected to the proper centrifugal force
C.The lube oil will overheat and flash
D.Oil will discharge from the heavy phase discharge port and be wasted

3.單項選擇題The size of the discharge ring used for the efficient operation of a disk type purifier is dependent upon the（）

A.rated capacity of that purifier
B.viscosity of the oil being purified
C.maximum design speed of that purifier
D.specific gravity of the oil being purified

4.單項選擇題In a disk-type lubricating oil purifier, （）

A.the purifier driving gears are lubricated by the reclaimed
B.oil as it leaves the bowl all dirt and sludge are automatically discharged with the cooling water
C.sealing water must never be supplied until after oil is fed to the unit
D.deterioration of the bowl ring gasket will cause the purifier to lose its water seal

5.單項選擇題In sewage treatment, the term maceration refers to the process of （）

A.breaking up solid matter into fine particles
B.precipitating non-decomposed waste in a collection tank
C.chemically adjusting the sewage ph to 7-0
D.eliminating bacterium coli from the sewage