Uncertainty estimation of a liquid flow standard system with small flow rates

• Published in: Measurement : journal of the International Measurement Confederation Vol. 51; pp. 367 - 376
• Main Authors: Chun, Sejong, Yoon, Byung-Ro, Choi, Hae-Man
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2014
• Subjects: Flow metrology; Fuel–oil flow meter; Uncertainty estimation; Water flow; Flow metrology; Uncertainty estimation; Water flow; Fuel–oil flow meter
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2013.12.002

•Jones method provided u(t) larger than ISO 4185 A.1.2 did by 4–10 times.•Correlation coefficient between ε and ρ was ca. 0.67 with little influence to U(Q).•uA(Q) became comparable with u(t) as t was increased to measure volume flow rate.•CMC could be declared from the uncertainty distribution as a function of flow rate.•CMC was (0.10–0.52)% (k = 2) when W was collected up to 10,000g. A liquid flow standard system is used to calibrate liquid volume of fuel–oil flow meters at small flow rates between 50 L/h and 700 L/h. However, the system has not been used to calibrate volume flow rate because the system is only operated with the standing-start-and-finish mode. In this study, the liquid flow standard system was rebuilt to provide a calibration service of volume flow rate by attaching two flow diverters, which can operate the system with the flying-start-and-finish mode. To evaluate its performance for volume flow metering, several techniques were introduced. First, diverter timing errors were estimated by linear regression. Second, covariance between buoyancy correction factor and water density was obtained to consider interdependency between the two measurands. Third, calibration and measurement capability (CMC) was evaluated by setting a fixed value of collected weight or elapsed time for flow diversion. Finally, several CMCs were compared to find the best measurement condition. As a result of the above approach, the CMC of the liquid flow standard system was found to be (0.10–0.52)% (k = 2) for (50–700) L/h with a minimum collected weight at 10kg.