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).
Comparative tests between a Zenith filter and a standard gauze filter for carburettors.
| Identifier | ExFiles\Box 44\1\ Scan067 | |
| Date | 30th December 1926 | |
| To Wd{Mr Wood/Mr Whitehead}/AW. from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} X3700 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG30.12.26. ZENITH FILTER. X3700 With reference to the letter from the Zenith Carburetter Co. enclosed with your Wd{Mr Wood/Mr Whitehead}/AW1/N29.12.26. We would like you to make the following reply :- "We have carried out careful comparative tests between the Zenith plate filter and our present standard gauze filter. We know it is possible, after a long period of running, for our gauze filter to get choked up on the road. We therefore consider the capacity of this filter is the absolute minimum for what we require. Tests of filters on the road require an indefinite period on a large number of cars to get a reliable figure of merit. We have therefore carried out careful comparative tests on a rig in which petrol, carrying in suspension a considerable quantity of foreign matter, was fed simultaneously through two carburetters via our own type of filter in one case and the Zenith filter in the other. In every case the filters got choked up before the jets, shewing that normally the gauze type filter is fine enough to prevent foreign matter blocking up the jet. However, we know that there is a certain type of foreign matter which will pass our gauze and cause trouble in the carburetter. The foreign matter which passed the filters shewed that edge filtration with plates was better than that of gauze. The main point however is that the Zenith filter consistently choked in about 1/12 the time of our standard gauze filter. We purposely arranged for a certain amount of vibration during the test but this did not approach road conditions. However, as a result of our investigations we are of the opinion that the capacity of the Zenith filter is too small, even supposing that road vibrations should, to a certain extent, assist in clearing it. We therefore require a larger capacity filter for our road tests. In spite of the accessibility and visibility of the Zenith type filter, we do not consider that any R-R owner should be expected to experience a voluntary stop on the road through clogging of this accessory." Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||