Evaluation of the uncertainty in capacity measurement of rail tankers

The uncertainty in capacity measurement of rail tankers (UCMRT) is researched according to China national metrological specification 'JJF1059-1999 Evaluation and Expression of Uncertainty in Measurement' and the mathematic models of capacity of rail tankers using the tank-internal/external geometric method are established respectively. According to analysis, calculation and evaluation, the expanded uncertainty in capacity measurement of rail tankers (EUCMRT) are 2.6 × 10-3 and 2.9 × 10-3 respectively for the tank-internal/external methods when the coverage factor is assumed to be 2, and satisfy 'JJG140-1998 Capacity of Rail Tankers' in which the EUCMRT should be less than 4 × 10-3 when the coverage factor is assumed to be 2, which indicates that the tank-internal/external geometric method is feasible. Research on both the volumetric and weighing methods should be initiated and automatic capacity measuring equipments for railway tankers should be researched and developed to improve the value transfer system of rail tankers with considerable accuracy and to be geared to international conventions.