ISO 9614-2 applied to an external gear pump: effect of geometric measurement parameters on the uncertainty

Due to its simplicity, ISO 9614-2 standard (scanning method) is probably the most applied to determine the sound power level from sound intensity measurements. The standard provides the "highest" standard deviation values of reproducibility, allowing for random errors associ-ated with the measurement procedure, for two grades of accuracy. Specific ancillary tests and calculations are required in association with the test measurements for achieving the desired grade of accuracy. However, even with these ancillary tests, the interval defined by the ex-panded uncertainty is too wide to be acceptable for validating numerical simulation or even to compare similar products. The authors performed repeated measurements on an external gear pump to investigate the influence of some geometric measurement parameters on the accura-cy of the determined sound power level. Previous results showed that the orthogonal scanning seems a reasonable requirement and that 3 repetitions look to be sufficient to have an ex-panded uncertainty value of repeatability lower than that indicated in ISO 9614-2.This paper presents further investigation on the effect of other variables, namely different measurement surfaces and different scan line densities.