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).
Guideline specifying three degrees of accuracy for instrument measurements and calibration.
| Identifier | ExFiles\Box 165\3\ img022 | |
| Date | 11th December 1920 | |
| Contd. -2- EFC3/T1.12.20. It is advisable to give the number of the instrument and the range used for any job, in case changes occur in the instrument. When anything happens to an instrument which might cause a change in its calibrations, this fact should be made known so that the accuracy of our results may not be disturbed, as has previously happened. A new calibration will then be arranged. For convenience we will specify three degrees of accuracy, as follows :- Accuracy 1. means an accuracy of ± ½%, i.e. an accuracy of ± ½ a division on 2/3rds full scale of the instrument. Results to this degree of accuracy are required in the majority of cases. Accuracy 2. means an accuracy of ± 2%, i.e. ± two divisions at 2/3rds full scale. This degree of accuracy is expected in dealing with ampere output results of dynamos, but in taking field currents, particularly for heating test results, accuracy 1. is essential. Accuracy 3. means ± 5%, i.e. ± 5 divisions at two-thirds full scale. This degree of accuracy is for rough work only, where more exact results are not required. In any uncertain case you may enquire as to what accuracy is expected. EFC. | ||