Further investigation into a water flow rig related to calibration

In the development of a flow test rig as a tool for investigating manufacturing variation, we encountered various problems. We discussed some of these in an earlier paper (Baker et al. (2006) [1]). In this paper we report on tests aimed at identifying the limits of accuracy of the rig and the best obtainable uncertainty with this type of design. We consider: traceability issues relating to the calibration of the weigh scales, seasonal variation, and sources of uncertainty in the flow system, and we deduce from these the limits of uncertainty. We also include some observations relating to the effect on meters of flow oscillation due to flow rate change.