Uncertainty Estimation of the Subdivision Method of Calibration Results on an Automatic Mass Comparator

摘要

According to OIML R111, for determining the conventional mass, there are two methods: the subdivision, and the direct comparison. Comparing with the direct comparison method, the functional relationship in the subdivision/multiplication method is very complicated. Thirteen calculation equations are used to provide an appropriate adjustment calculation so as to avoid propagating errors. The effect of the correlations cannot be ignored during the uncertainty estimation. This manuscript took a set of mg weights as an example, and focused on the uncertainty estimation of the subdivision method of calibration. The uncertainty components were the reference weight uncertainty, the uncertainty of the weighing process, the air buoyancy uncertainty, and the uncertainty of mass comparators, etc. According to the OIML R111 Annex C and the EA-4/02, the uncertainty components were evaluated either by the Type A method or by the Type B method. With fully considering the covariance of the components, the uncertainty of mass calibration in subdivision method was properly estimated.