Reclaiming Used Engine Oil
Page 65
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An Interesting New De Laval Plant Constructed for the Benefit of Vehicle Users ONEof the troubles which always faces the maintenance engineer is that of the replacement of oil in the crankcase. Generally speaking, the quantity actually consumed is of less moment than that which has to be drained, off and replaced by fresh oil. The old lubricant is contaminated by colloidally dispersed carbon, and is diluted by the heavy ends of the fuel. The latter is a particularly prominent trouble in the case of oil engines and is one of the chief difficulties under•which manufacturers of these power
units are now labouring.
Probably no concern has had more experience in the purification of liquids than Alfa-Laval Co., Ltd., 34, Grosvenor Road, London, S.W.1, for it has, specialized on the production of centrifugal purifiers for all classes of fluid. This company has carried out extensive researches with regard to the reclamation of used crankcase oil and is now offering its SF equipment, which is of Particular interest to operators of large fleets.
In Order to be fit for further use in an engine, the reclaimed oil should be Perfectly free from sludge, carbon, metal particles, water and other mechanical impurities ; in addition, it should have approximately the same viscosity and flash point as a new oil, whilst it should also be cheaper than new oil. Merely to filter a used lubricant is not enough, because finely dispersed carbon, water and the fuel dilution remain in the oil.
The De Laval SF equipment consists of an oil separator driven by an electric motor, two oil tanks (one of which is heated), a filter press, two oil-transfer pumps and the necessary piping, valves, switches and fuses.
The oil is treated in two stages. Dirt and water are completely removed by means of repeatedly passing the hot oil through the separator. Simultaneously, most of the carbon is removed and thefuel dilution is distilled off, whereby the original viscosity of the oil is restored. Next, a special kind of fuller's earth is mixed with the oil, and the liquid is then filtered. The earth has a decolouring effect and neutralizes any acid-decomposition products remaining in the lubricant. .
The time required for the process is about five hours and the yield is over 80 per cent. In the case of one series of results, the flash point of the oil after treatment was 392 degrees C. as opposed to 195 degrees C. when new, and the viscosity at 20 degrees C. after treatment was 820 seconds R. as opposed to 830 seconds R. when new.
Three sizes of SF equipment are marketed. One will treat 8.5 gallons at a time, another 18 gallons, and another 36 gallons.