New Primary Standard With Piston Prover For Microflow Of Liquids

Miroslava Benková, František Schweitzer

Abstract

The Czech Metrology Institute continues in development of a method in the area of very small flows of liquid aimed at reducing uncertainties and expanding flow to lower values. The primary standard developed based on mass method has successfully been internationally compared and the results have shown data stability. With increasing accuracy of flow meters on the market, requirements for reduction of uncertainty of primary or secondary standards are rising.<BR />In case of very small flows, i.e. below 10 ml/h, some calibrations and subsequent result evaluations by means of the weighing method become a little complicated. With the aim to automate the calibration process as well as to reduce uncertainty of measurement and also enlarge the range to lower flows, an innovative primary standard with 200 mL micro piston prover has been developed. Long-term experience with development of a volumetric method using a similar type of piston prover with a special fluid displacement system in the area of the larger flows was applied.<BR />The paper is focused on the presentation of the comparison of measurement results between the volumetric standard with the piston prover and gravimetric standard in one place. A detailed design of the new test equipment with integrated micro piston prover into the testing line is presented as well. Further, experimental measurements in very low flow rates (1 to 6,000) ml/h are described and evaluated. Achieved measurement uncertainties are also presented. The results show the benefits of the applied method.

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DOI

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IMEKO TC

TC9 - Flow Measurement

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