The geometry of three types of sinkers used during the calibration of hydrometers by the ring method in a density standard liquid was studied. An experiment was designed with two factors: the geometry and the metrologist, with three levels for the geometry of sinkers and two levels for the metrologist factor. Even when the variable under study was the geometry, it was useful to observe the variation due to the metrologist when same method, system, hydrometer, and the temperature was used (reproducibility of the metrologist). Two response variables were monitored: the measurement bias and the time to carry out the calibration at one point. The calibration point selected was the closest point to the sinker in the measurement scale. The results show that the best geometry regarding measurement bias also results in the worst geometry regarding the productivity of the calibration laboratory, that is, the geometry which gives the lower time for calibration is also the geometry with the bigger measurement bias, and vice versa. These results allow the calibration laboratories to choose the best trade-off design of the sinkers to use for calibration of hydrometers in a density standard liquid.
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