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).
Comparison report on Exide and Perfection make syringe hydrometers.
| Identifier | ExFiles\Box 44\5\ Scan064 | |
| Date | 18th August 1923 | |
| EFC. JB 16. 18.8.23. X.3741 - RE COMPARISON OF SYRINGE HYDROMETERS. Two syringe hydrometers, one of the Exide make and the other Perfection were compared with the standard Twaddell hydrometer in various strengths of acid. Both of them read the same from 1.320 down to 1.230 but all the readings were .005 lower than the standard. Then below this S.G. the Exide hydrometer readings were more in error still, because when the S.G. was 1.130 by the standard, the Exide reading was 1.115 being an error of .015, whilst the Perfection hydrometer readings were higher than the standard by .005. By this means the Perfection hydrometer was found to be the more accurate of the two makes. Good and bad points of the Exide. (1) The barrel widens at about the centre and therefore does not allow the float to stick. (2) The figures and graduations on the float are clear and an accurate reading can be taken. (3) In the place where the barrel widens, the drawing down of the tube leaves a weakness, introducing liability to crack. The sample we have used in the test is notably weak at this point. (4) Sometimes the acid comes in the hydrometer with a rush and shoots the float upwards and it hits the glass at the top of the barrel and is liable to break it. Good and bad points of the Perfection. (1) Straight barrel making easier to clean and is also thicker than the Exide, making it more substantial. (2) The float can go right up into the bulb without banging up against anything. (3) One-piece nozzle of rubber, the stem of which is also of good length. (4) The figures on the float are clear (but not so clear as the Exide) and an accurate reading can be taken. Contd. | ||