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).
The effects of heat on moulded bakelite H.T. wiring tubes, with a comparison to vulcanite covering.
| Identifier | ExFiles\Box 61\1\ scan0107 | |
| Date | 10th April 1930 | |
| COPY. WE.16. 10.4.30. EFFECT OF HEAT ON MOULDED BAKELITE H.T. WIRING TUBES. We have carried out tests on the bench to ascertain the effect of various temperatures on the moulded bakelite H.T. wiring tubes as standard on the 20/25. and proposed for the Phantom II chassis. For this purpose a 6" length of tube was placed in the electric oven and heated for one hour at 150°C. one hour at 200°C. and one hour at 250°C. the heat effect on the bakelite being observed at each temperature. After one hour at 150°C. no change was observed in the condition of the tube. After one hour at 200°C. the colour of the bakelite changed to dark brown, but otherwise there was no appreciable effect. Upon raising the temperature to 250°C. cracking noises were heard coming from the tube and upon examination at the end of one hour the tube was found to have turned nearly black in color, was blistered on the surface and was very brittle, showing that the bakelite was near the carbonization point. It appears therefore, that for these tubes to remain satisfactory as regards appearance and dielectric condition, the temperature to which they are subjected should, as far as possible, not exceed 150°C. and certainly not more than 200°C. As a comparison a sample of the vulcanite covering, as applied to present standard 40/50 wiringtubes was also similarly heated. At 150°C. the vulcanite became very soft and could easily be bent through 90°. At 200°C. the vulcanite practically melted being very plastic and completely blistered and distorted. EFC/HEW. | ||