Chevrel Magdalena Oryaelle auteur aut IRD Latchimy T. auteur aut IRD Batier L. auteur aut IRD Delpoux R. auteur aut IRD Harris M. auteur aut IRD Kolzenburg S. auteur aut IRD text journalArticle eng text/pdf born digital access Mounted on top of furnaces, laboratory viscometers can be used for the rheological characterization of high temperature melts, such as molten rocks (lava). However, there are no instruments capable of measuring the viscosity of large volumes of high temperature melts outside the laboratory at, for example, active lava flows on volcanoes or at industrial sites. In this article, we describe a new instrument designed to be easy to operate, highly mobile, and capable of measuring the viscosity of high temperature liquids and suspensions (<1350 degrees C). The device consists of a torque sensor mounted in line with a stainless-steel shear vane that is immersed in the melt and driven by a motor that rotates the shear vane. In addition, a thermocouple placed between the blades of the shear vane measures the temperature of the melt at the measurement location. An onboard microcomputer records torque, rotation rate, and temperature simultaneously and in real time, thus enabling the characterization of the rheological flow curve of the material as a function of temperature and strain rate. The instrument is calibrated using viscosity standards at low temperatures (20-60 degrees C) and over a wide range of stress (30-3870 Pa), strain rate (0.1-27.9 s(-1)), and viscosity (10-650 Pa s). High temperature tests were performed in large scale experiments within similar to 25 l of lava at temperatures between 1000 and 1350 degrees C to validate the system's performance for future use in natural lava flows. This portable field viscometer was primarily designed to measure the viscosity of geological melts at their relevant temperatures and in their natural state on the flanks of volcanoes, but it could also be used for industrial purposes and beyond. specialized 020 066 94 10 105116 [11 ] 2023 0034-6748 https://www.documentation.ird.fr/hor/fdi:010088718 10.1063/5.0160247 0034-6748 [F B010088718] https://www.documentation.ird.fr/hor/fdi:010088718 https://www.documentation.ird.fr/intranet/publi/2024-01/010088718.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2024-01-12 2025-02-24 fdi:010088718 fre