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 concerning thermostat bellows failure and proposed testing of experimental units.
| Identifier | ExFiles\Box 156\2\ scan0025 | |
| Date | 16th February 1938 guessed | |
| Page 2. Messrs. Rolls-Royce Limited. state on your drawing that the free length of the bellows had to be such that in the event of failure of the thermostatic element the radiator valve would open fully, our Drawing did specify this, and there is no doubt that as originally delivered the bellows was correct in this respect. In view of your experience with the standard Vauxhall Thermostat, modified to give perfect balance, it seems probable that the total pressure within the system has been responsible for this loss of length by deforming the relatively light walls of the bellows. We are therefore making up a unit using similar bellows, and we will subject this to a 20 lbs/sq.in. pressure test for 24 hours to ascertain whether or not loss of length does take place. At the same time we are making up an experimental unit with bellows having wall thickness of .007", and if we can get satisfactory temperature operation we will test this bellows with an external pressure of 20 lbs/sq.inch to ascertain whether it is strong enough to resist this pressure without loss of length. As soon as the tests are completed, we will write you again. Yours truly, THE BRITISH THERMOSTAT COMPANY LIMITED. W. Martin-Hurst. Director. ENC. Drawing No. to follow. | ||