From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Analysis of an oil filter's components and its performance in removing contaminants and acidity from sump oil.
Identifier | ExFiles\Box 135\3\ scan0221 | |
Date | 8th January 1938 guessed | |
TYPE No2 PATENT No 412204 SMITH'S OIL FILTER MADE IN ENGLAND TO AVOID EXCESSIVE ENGINE WEAR THIS CARTRIDGE SHOULD BE REPLACED WHEN OIL BECOMES VISIBLY DIRTY. A.33243. Fig. 3. Internal parts of oil filter. Fig. 4. Filter unit showing crimped edges and embossing which separate each unit. In view of this analysis, it was decided to investigate the quantity of iron to be found in sump oils. Ten c.c. of sump oil was extracted and diluted heavily with filtered petrol. A horse-shoe magnet was embedded in wood to form a framework to hold a thin sheet of cellophane over the poles, and was then dipped into a porcelain dish holding the diluted oil. The contents were agitated gently for some considerable time, and then the magnet and cellophane were lifted out and washed in petrol. Finally, when dried, the cellophane was removed from the magnet, and the resulting deposit of magnetic material photographed. Fig. 8 shows the quantity of magnetic material extracted from 10 c.c. of sump oil. Reading from left to right, they are:— 10 h.p. car with no filter after 1,546 miles. 14 h.p. car with competitor's filter after 1,593 miles. 12 h.p. car with Smith Filter after 7,042 miles. Digest of slime from filter, equivalent to 10 c.c. of sump oil. It will be seen that the oil from the sump with a Smith Filter contains considerably less iron than with the competing filter, although the oil had been in for almost five times as long. A further quantity of dirty sump oil was collected and passed through the filter. Samples were taken before and after testing for acidity by shaking with hot water for 30 minutes, separating the water and titrating with N/100 sodium hydroxide solution in presence of methyl orange. The results showed that, considering the acidity as being H₂SO₄, the original dirty oil contained 0.0014 per cent., whereas after filtration the acidity was nil. It is claimed then that the Smith Oil Filter returns absolutely clean oil to the sump, even removing colloidal carbon. In this respect it is in advance of any other filter. During the early stages of use the foreign matter extracted from the oil helps to form a filter bed which is capable of extracting the very finest particles. Later, this bed increases in thickness until there is difficulty in getting oil to penetrate it. The flow through the filter then gradually fails, and the sump oil, in consequence, grows darker and darker. There is thus an obvious indication of when a change of filter is necessary. The removal of acidity by this filter, leading to less chemical corrosion, appears to be due to the fact that the acidity is present in conjunction with the sludge. | ||