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).
Hydraulic resistance, temperature, and end adaptor tests on copper and 'Superflexit' tubing.
| Identifier | ExFiles\Box 88\5\ scan0202 | |
| Date | 1st August 1929 guessed | |
| 3. E.2861 It is extremely improbable that this tubing would fail in Service from vibration. 2. Hydraulic Resistance Since the internal surface of this tube is rather irregular by reason of the internal brass wire, it was thought that the hydraulic resistance would be high relative to plain copper tube. The hydraulic head required to produce definite flows through 6 ft. lengths (straight) of pipes was therefore measured. The pipes tested were :- (a) Copper 14.3 m.m. & 24 m.m. I.D. (b) Copper 14.3 m.m. & 24 m.m. but with "Superflexit" ends attached. (c) Superflexit 16 m.m. and 24 m.m. with their own ends. These sizes of copper were the nearest obtainable size to the "Superflexit" tubes. The flows at which the resistances were measured corresponded to mean water velocities of up to 10 ft. per second. Curves are attached - see Figs. II and III - which show the hydraulic resistance of all these tubes, and Fig.IV attached shows in tabular form the extra head over that required for copper tubes to produce the same flow. After reference to curves on Figs.II and III, and figures on Fig.IV, it will be seen that the 24 m.m. "Superflexit" tube requires about 200% more head than a copper tube of similar bore to produce the same flow, and the 16 m.m. size about 300% more than that required by a copper tube of 13.4 m.m. bore. This represents a rather high hydraulic resistance but the lengths of tubes tested were long and the difference in friction losses may be less with the more viscous oil than with water as tested. 3. Temperature Subsequent to the hydraulic resistance tests the 6 ft. length of 16 m.m. was installed in a high temperature oil circuit using P.4 oil under a pressure of 50 lb.per sq.inch and a temperature of 100°C. At the end of 60 hours of this treatment it was split open for internal inspection. The specimen successfully withstood this test for 60 hours, at the end of which one or two small spots of oil had appeared through the braiding but burned hard and were self sealing. The rubber gland joints were quite satisfactory. On opening up the tube for inspection it was found that the "cellophane" lining had become harder than normal, but was in good condition. 4. End Adaptors. In order to ascertain whether any difficulty would be encountered in fitting the ends, a number of ends were fitted to portions of tube cut out of the above 24 m.m. 6 ft. length. These were tested by internal pressure of paraffin. These / | ||