Question 623Steam Plants - Assistant Engineer

The correct answer is A) Diesel fuel oil. A centrifugal purifier is effective at removing water, metal particles, and carbon particles from marine lubricating oil, but it cannot effectively remove diesel fuel oil. Diesel fuel oil has a similar density to the lubricating oil, so it will not be separated out by the centrifugal forces in the purifier. The other impurities, being of significantly different densities, can be effectively removed. Therefore, of the options provided, diesel fuel oil is the one that cannot be removed by a centrifugal purifier at normal operating speeds and temperatures.