Microflow and nanoflow rate calibrations are important in several applications such as liquid chromatography, (scaled-down) process technology, and special health-care applications. However, traceability in the microflow and nanoflow range does not go below 16 μl/min in Europe. Furthermore, the European metrology organization EURAMET did not yet validate this traceability by means of an intercomparison between different National Metrology Institutes (NMIs). The NMIs METAS, Centre Technique des Industries Aérauliques et Thermiques, IPQ, Danish Technological Institute, and VSL have therefore developed and validated primary standards to cover the flow rate range from 0.1 μl/min to at least 1 ml/min. In this article, we describe the different designs and methods of the primary standards of the gravimetric principle and the results obtained at the intercomparison for the upper flow rate range for the various NMIs and Bronkhorst High-Tech, the manufacturer of the transfer standards used.
In the field of water content measurement, the calibration of coulometric methods (e.g., coulometric Karl Fischer titration or evolved water vapor analysis) is often overlooked. However, as coulometric water content measurement methods are used to calibrate secondary methods, their results must be obtained with the highest degree of confidence. The utility of calibrating such instruments has been recently demonstrated. Both single and multiple point calibration methods have been suggested. This work compares these calibration methods for the evolved water vapor analysis technique. Two uncertainty estimation approaches (Kragten’s spreadsheet and M-CARE software tool) were compared as well, both based on the ISO GUM method.
Abstract. CETIAT is a calibration laboratory accredited by COFRAC. The temperature generators are stirred calibration baths (from -80 °C up to +215 °C), dry blocks and furnaces (from -90 °C up to +1050 °C) and thermostatic chamber (from -30 °C up to +160 °C). The best calibration uncertainty is achieved in calibration bath, for Platinum Resistance Thermometers (PRTs), it is 0.03 °C. Nevertheless, the daily calibrations lead to an uncertainty about 0.06 °C for industrial RTD sensors. The CETIAT is working on the implementation of a Gas Controlled Heat Pipe (GCHP) temperature generator to replace the thermometric baths in order to increase productivity and in order to improve temperature stability in the working volume of the generator. Many studies [1,2], explain the advantage of this method. For this purpose, the new system must have better thermal performance and produce the same temperature range than the stirred baths.Two years ago, the CETIAT characterized a water GCHP for industrial applications cover the temperature range from +30 °C up to +150 °C [3]. The results were in good agreement with the expectations and water GCHP could be used to calibration production. But, we need to extend the temperature range towards the low temperatures. This year, the CETIAT characterized a new type of ethanol's heat pipe. We used the same heat pipe but this time we replaced water by ethanol. The possibilities of using ethanol, would allow generation of temperatures between -40 °C and 30 °C low temperature enclosure.This article presents the first results on the study of a low temperature heat pipe made at CETIAT. The results obtained during the metrological characterization, in terms of temperature homogeneity and stability, in this study are encouraging. However, an issue with the stability of the cooling system diminish the quality of the results. The stability of the surrounding environment must be improved. This will be the subject of a future study. The results at 20 °C are very positive. Over an axial length of 250 mm, the thermal homogeneity is less than 5 mK.
Abstract. The CETIAT thermometry calibration laboratory has a wide range of temperature generators. Overflow baths, dry furnaces, furnaces as well as thermostatic chambers make it possible to achieve a temperature range from -90 °C to 1050 °C. Experience gained over more than ten years enables the teams to identify possible measurement difficulties. The thermal characterisation of portable furnaces is identified as risks in measurement errors. The diversity of CETIAT's calibration tools makes it possible to highlight these risks and to find solutions for them. Only a few documents deal with the characterisation of portable furnaces. The EURAMET guide "cg-13 form 3.0 (02/2015)" provides some elements. This lack of information on implementation in temperature calibration furnaces can lead to significant calibration errors. A calibration performed in a thermostated bath or dry furnace will give different results in both the correction and the associated uncertainty. The difference in the results obtained is such that the corrections do not overlap, even when taking into account the associated uncertainties. There is also the effect of the environment on the results. This study allows users of portable furnaces to reduce measurement errors due to poor implementation.
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