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An EMPIR project for traceability in liquid density measurements at emerging NMIs has presented a paper at a measurement conference

Liquid products are used across a range of industries, including food, pharmaceuticals, and energy production. As many of these applications characterise liquids by mass and volume, traceability and accuracy for liquid density measurements are vital. However, across Europe, there is a lack of technical capability around these measurements at emerging National Measurement Institutes (NMIs), meaning they are unable to deliver the high-level calibration services needed by industry.

EMPIR project Establishing traceability for liquid density measurements (17RPT02, rhoLiq) has coordinated the development of new systems at emerging NMIs, producing validated reference materials and contributing to international standards on liquid density measurements.

Conference paper

The project studied the effects of viscoelasticity in non-Newtonian liquids on the accuracy of hydrostatic weighing (HW) meters and oscillation-type density (OD) meters, as well as how these effects may be overcome at NMIs. HW meters are devices which use displacement to measure density, while OD meters use the dampening effect of a liquid’s known viscosity. Two viscoelastic liquid samples were prepared by IPQ and tested by five project partners (IPQ, GUM, PTB, TUBITAK and IMBiH), using both methods. From the results of this study, a paper, titled “First density comparison on viscoelastic samples with hydrostatic weighing method”, was written. This paper was then accepted for presentation at the joint IMEKO TC1, TC7, TC13, TC18 and MATHMET Symposium 2022, held in Portugal in August 2022.

Other project achievements

• A good practice guide and three new draft guides

Three EURAMET guides for hydrostatic weighing, oscillation-type density meters, and for the production of certified reference materials for density have been drafted for review, alongside to a newly produced “Good practice guide for the measurement of the density of liquids in industry”, which is publicly available.

• Enhanced calibration capability

Following work by the project, project participants are now able to claim Calibration and Measurement Capability (CMC) for density measurements at the CIPM MRA database (KCDB).

• Stakeholder workshop

The results of the project’s hydrostatic weighing meter and oscillation-type density meter robustness studies were compiled in a report, which was presented to the stakeholder community during a workshop, drawing an attendance of around 80 participants. Sections of the workshop are available to view online.

Project coordinator Andreia Furtado (IPQ) has said about the project:

“This work provided, for the very first time, a great understanding of the effects produced by the viscoelasticity of non-Newtonian liquid samples on the density measurements results carried out through hydrostatic weighing, and about how the NMIs overcome these effects. These results allowed to improve the degree of equivalence of density measurements of viscoelastic samples performed with oscillation-type density meters.”

This EMPIR project is co-funded by the European Union's Horizon 2020 research and innovation programme and the EMPIR Participating States.

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