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).
Letter to the Autovac Mfg. Co. Ltd. querying the function of a non-return valve in a new measuring Autovac system.
| Identifier | ExFiles\Box 40\4\ Scan149 | |
| Date | 30th November 1925 | |
| X3529 Expl: Dept: 30th.Nov.1925. Hs{Lord Ernest Hives - Chair}/AJL1/LG. The Autovac Mfg. Co.Ltd., Heaton Norris, Stockport. Dear Sirs, With reference to your letter ref. SG{Arthur F. Sidgreaves - MD}/LG19.11.25. and drawing MA.3. We notice that in the new measuring Autovac you include a non-return valve in the petrol supply pipe. We should be obliged if you would let us know what advantages accrue from the inclusion of this valve; it does not appear to be a necessity to the correct functioning of the Galometer in conjunction with which this Autovac is to be used. Perhaps there is some advantage to be gained by not allowing the petrol in the supply pipe to return to the tank each time the Autovac functions? There is one other point with regard to the correct functioning of the Galometer which we should like to raise. From a perusal of the drawings which you have supplied, it is evident that the correct functioning of the instrument is dependent upon the Autovac float moving through the same stroke every time and so admitting exactly the same quantity of petrol each time it functions. If the Autovac can supply more petrol than the engine demands, the instrument can work correctly, the float will fall its max. stroke each time before more petrol is admitted, and the same quantity of petrol will be admitted each time, under these conditions the float chamber is never completely empty. Now suppose we take a case where the Autovac is incapable of supplying enough petrol to meet the engine demands; we will say for the sake of argument that the petrol level in the outer Autovac reservoir has fallen below the level of the flap valve at the bottom of the float chamber and that the engine is consuming more petrol than the Autovac can supply. In this case the Autovac will be functioning quickly in an attempt to make up the leeway, and every time the air release valve opens, all the petrol in the float chamber will be precipitated into the outer reservoir before the valve can close again and admit more petrol, contd :- | ||