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 from The British Thermostat Co., Ltd. explaining the operation of a valve and referencing drawing No.11295/A.
| Identifier | ExFiles\Box 156\2\ scan0221 | |
| Date | 25th April 1939 | |
| .1328 Telephone: SUNBURY-ON-THAMES 456 (6 LINES) Telegrams & Cables: THERMOSTAT, SUNBURY-ON-THAMES. Code: BENTLEY'S THE BRITISH THERMOSTAT CO., LTD. Makers of Scientific Instruments. DIRECTORS: COL. N. HUDSON. J.{Mr Johnson W.M.} E.{Mr Elliott - Chief Engineer} SHERLOCK } MANAGING. W. P. F.{Mr Friese} MARTIN HURST } F.{Mr Friese} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} POPLETT. F.{Mr Friese} PARMENTER. TEDDINGTON WORKS. Windmill Road, Sunbury-on-Thames, Middlesex. ON A.I.D. AIR MINISTRY APPROVED LIST. EDWARDS Our Ref. KMP/OH. Your Ref. Rm{William Robotham - Chief Engineer}/Ed.{J. L. Edwards}6/JH. 25th April 1939. Rolls-Royce, Ltd., Derby. Dear Sirs, For the attention of Mr. Robotham. We thank you for your letter of the 21st instant, and with reference to your first query we would refer you to our letter of the 20th instant in which, after we had realised the mistake, we enclosed a further drawing No.11295/A shewing the necessary modification. From your remarks about our valve being more complicated than yours we think perhaps you do not quite understand how it works, and we give below a description for your information. Will you please refer to one of the prints of drawing No.11295/A sent herewith on which we have marked letters indicating the various parts :- When cold the valve seat H, which is of the same area as bellows B, is held on to its seal merely by the 2 1/2 lb. splash spring I. The space between the bellows B and the outer casing A is charged with the coolant you are using, i.e. water, thus at 100°C the charge vapourises and the inside plate of the bellows D moves upwards until it hits on the variable stop C. At this point the vapour pressure acting on the valve H is balanced by the same vapour pressure inside the bellows, acting on the same area in the opposite direction. As the temperature rises this balance is maintained. (contd.) | ||