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 regarding the testing of two thermostats, model EB.3509, one of which was found to be faulty.
| Identifier | ExFiles\Box 156\2\ scan0123 | |
| Date | 12th September 1938 | |
| Telephone: SUNBURY-ON-THAMES 456 (6 LINES) 1328 Telegrams & Cables: THERMOSTAT, SUNBURY-ON-THAMES. Code: BENTLEY'S THE BRITISH THERMOSTAT CO., LTD. Makers of Scientific Instruments. Windmill Road, TEDDINGTON WORKS. Sunbury-on-Thames, Middlesex. DIRECTORS: COL. N. HUDSON. J.{Mr Johnson W.M.} E.{Mr Elliott - Chief Engineer} SHERLOCK W.F.F. MARTIN-HURST } MANAGING. L.S. SWINNERTON DYER. F.{Mr Friese} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} POPLETT. WMH/GN: Your Ref: Rm{William Robotham - Chief Engineer}/Std.1/MH{M. Huckerby}: September 12th, 1938. Messrs. Rolls-Royce Ltd. DERBY. Dear Sirs, We apologise for the delay in replying to your letter dated September 7th. We have very carefully tested the two Thermostats, EB.3509, which you have returned to us, and find that the one which you state opens at 78°C. by our test opens at 76°C. and is therefore correct. We agree that the other does open at 73°C. which is too low. As the writer explained to Mr.Steadman on the telephone this morning we are installing a pump to circulate water through the casing, so as to make sure that there is no difference in temperature between the inside of the casing and the outside. We also confirm that we have doubled up the test on these units, and the procedure is as follows:- The temperature is first set, then they are given 48 hours in the pressure drum in order to check for leakage. They are then inspected for appearance and date stamped, and finally they are re-temperature tested. We confirm that in future designs it will be very helpful if the pin of the spindle in the end of the bellows plate can be discontinued, as if [Signature] | ||