Filtration it Importance in Engine Life
Page 49
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IN his paper on filtration, which he presented at a meeting lof the Diesel Engine Users Association, held in London yesterday, Mr. C. G. yokes, A.M.LMech.E., A.F.R.Ae.S., N.S.A.E., M.I.A.E., gives facts and figures which go to prove how vitally important it is to provide for the effective filtration of air, oil and fuel.
In England, he says, air contamination ranges from about f oz. to 6 oz. per 100,000 cubic ft., and for 1 ton of coal burned, about 50 lb. of carbon and other products pass into the atmosphere.
Dealing with experiments conducted on light Tank engines, the author says that the finest dust-0 to 24 microns—was responsible for about one-third less top-cylinder wear, and two-thirds less top-piston-ring wear, than dust containing particles of 0 to 40 microns.
Mr. Yokes, quoting from records obtained from practical experience, says that as much as 7 lb. of dust was trapped by an efficient filter used on a Tank engine during a test in the Long Valley at Aldershot. The same Tank, fitted with a pair of filters, gathered 30 lb. of dust in 100 miles while operating in the desert.
In dealing with the various types of air filter available, such 'as the oil-wetted and oil-bath types, his comments are that they require careful and periodical servicing. Centrifugal filters of the self-cleaning type can, he says,be relatively costly and limited in their application. Positive dry
fabric filters can be produced to give satisfactory results without need for attention.
From his remarks on oil filtration, one is left in no doubt that Mr. Vokes advocates the use of the full-flow type, as opposed to that type of filter which is fitted so as to deal with only a partial flow of the oil.
Generally speaking, he says, there is a tendency to fit oil filters which are too small. Price in the first instance, and space limitations in the second, are given as possible reasons.
Despite the fact that the oil companies, as the author says, see that the products they supply are scrupulously clean, it is difficult to avoid subsequent contamination. For this reassm it is essential to have an adequate filter on the inlet side of the fuel-oil tank. Actually, there should be three distinct stages of filtration. In the first stage a finemesh non-ferrous gauze should be provided to remove large particles. The second is the use of a standardized corrugated felted fabric, and the third a miniature "felt hat," which removes the finest particles.
Mr. Yokes concludes his paper with a reference to the British Society of Associated Filter Manufacturers, which has recently been formed. Its aim is to seek recognized standards for air, oil, fuel and other types of filter, which, it is hoped, will result in engine builders being able to buy products backed by a guaranteed performance.