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).
The issues with zinc diaphragms in S.U. Petrol Pumps when exposed to alcohol-based fuels.
| Identifier | ExFiles\Box 149\1\ scan0224 | |
| Date | 13th January 1936 | |
| To By.{R.W. Bailey - Chief Engineer} c. to Hd.{Mr Hayward/Mr Huddy} X1263 Hs{Lord Ernest Hives - Chair}/Bwg.{J. C. Bowring}20/KW.13.1.36. S.U. Petrol Pumps. Ref: Hd{Mr Hayward/Mr Huddy}/SB.{Mr Bull/Mr Bannister}7/HR.7.1.36. The main objection to zinc diaphragms is that the dope with which the fabric is treated is soluble in alcohol. The S.U. Co. agree that this is so We have soaked a diaphragm in alcohol and found that it definitely is soluble; this fact is emphasized if the fuel is heated slightly. L.P's car has zinc diaphragms fitted and we believe he is running on Discol, however we have not heard that he has yet experienced trouble. 1-B-IV has covered approx. 7,500 miles on zinc diaphragms, without trouble, though Ethyl spirit has been mostly used. 3-B-IV is running with one zinc diaphragm, the other being standard. Ethyl is mostly used on this car. One other interesting experiment was that one of these diaphragms was fitted to a car which was run on Dominion & Cleveland No.3 spirit. After approx. 1,500 miles the diaphragm failed and petrol leaked through the drain hole. On inspection we found that the surface was a series of minute cracks. At the first opportunity we will inspect the diaphragms on Lp{Mr Lappin}'s car and report further. Until we know something more definite about these, we cannot recommend them for customers' cars. Hs{Lord Ernest Hives - Chair}/J.C.Bowering. | ||