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).
Comparison of bye-pass oil filters from various manufacturers.
| Identifier | ExFiles\Box 135\3\ scan0262 | |
| Date | 23th March 1938 | |
| COMPARISON OF BYE-PASS OIL FILTERS. In order to obtain a direct comparison regarding the relative figure of merit in cleaning oil between various maker's bye-pass filters, a rig was employed consisting of the following. Normal lower half with motor driven oil pump circulating the oil at 70°C. the delivery line being controlled by relief valve to 30 lbs/sq.in., from which a tapping was taken to the filter. Each filter was tested independently and started off with 2 gallons of dirty oil collected from repair cars and run until the oil reached a stable condition where it was not getting any cleaner. The method of checking the cleanliness value of the oil is confirmed as shewn on the attached photograph in two ways - (a) Actual photograph of spots of oil samples on blotting paper. (b) Photo-electric cell recording of light passed through a glass sandwiched oil film, the ammeter being set to read 100% for new oil and corresponding percentage of light reflection on this basis for the dirty oil. General Filter (U.S.A) Regarded in the order of merit, the General is the most efficient and as shown in line (1) of the photograph, recovers oil from 5% to 85% in 7 hrs and given a further 2 gallons of dirty oil at 27% recovers it to 72% in 14 hrs. (line 1.A). It is unfortunate that this type of filter is not manufactured in this country as other than its efficiency it possesses several other desirable features, namely:- (1) Has a detachable cleaning element cartridge which can be renewed without having to undo unions etc. as illustrated in attached phamphlet. (2) New Cartridge costs only 1s. 6d. (3) Considering value for money, initial cost at 7s. 6d. is low. A.C. (A.C.Spark Plug Co.) Next to the General filter comes the A.C. which recovered the first 2 gallons of dirty oil from 48% to 83% in 10 hrs. (line 3) and the second 2 galls from 23% to 47% in 7 hrs. (line 3.A.) This is the type that has been adopted on Wraith and has the advantage of a low initial cost 3/- but the disadvantage of undoing union and the clip when a renewal is required. continued | ||