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 British Thermostat Co. Ltd. outlining thermostat testing procedures and returning defective units.
| Identifier | ExFiles\Box 156\2\ scan0122 | |
| Date | 7th September 1938 | |
| The British Thermostat Co.Ltd. -2- 7th. September 1938. Will you please ensure, therefore, that all thermostats delivered, either new ones or ones returned for correction, are definitely within the drawing temperature limits - we prefer the opening temperature to be on the low limit rather than the high one. Our method of checking is to raise the temperature of the thermostat unit in its casing very slowly and note the temperature inside the housing when it is just possible to move a .002 feeler around the valve seat edge, without the feeler being tight anywhere. We then allow the water to cool slowly and note the temperature when the reverse applies - the mean of these two temperatures gives the opening temperature of the unit. We have found this method to check up well in the past with your thermostats and with other people's so that we think it is a reliable one. We are returning to you the two defective units complained of above and should like to receive them back for production at the earliest possible moment. Yours faithfully, for ROLLS-ROYCE LTD. | ||