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On-site calibration system for trace humidity sensors |
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| Affiliation: | 1. Federal Institute for Materials Research and Testing (BAM), D12203 Berlin, Germany;2. Lublin University of Technology, Department of Automation and Metrology, 20-618 Lublin, Poland;1. University of Belgrade, Technical Faculty in Bor, V.J. 12, 19210 Bor, Serbia;2. DIMES, University of Calabria, Via Pietro Bucci cube 44, 87036 Rende (CS), Italy;1. Department of Cartographic Engineering, Geodesy and Photogrammetry, School of Civil Engineering (UPV), 46022 Valencia, Spain;2. Department of Graphic Expression in Architecture, School of Architecture (UPV), 46022 Valencia, Spain;3. Polytechnic High School of Lugo, University of Santiago de Compostela, 27002 Lugo, Spain;1. Department of Mechanical Engineering, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada;2. Department of Mechanical Engineering, École de Technologie Supérieure, Montréal, QC H3C 1K3, Canada;3. Department of Engineering Physics, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada;1. Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 12116 Prague, Czech Republic;2. Institute of Physics, Pedagogical University, Podchorazych 2, 30084 Kraków, Poland |
| Abstract: | A portable device for calibration of trace humidity sensors and an adopted calibration procedure have been developed. The calibration device is based on humidity generation by permeating water through polymeric membrane tubes. Water vapour transmission rates for various polymers were experimentally determined in order to select the most suitable polymeric material. The developed trace humidity generator consists of a gas-flow polymeric hose immersed in a water reservoir thermostated by a sensor-controlled heater. Mole fractions of water vapour between 1 μmol mol?1 and 350 μmol mol?1 (equivalent to frost-point temperatures from ?76 °C to ?31 °C) were generated by varying either the operating temperature or gas flow. The operating temperature can be varied from 20 °C to 60 °C and kept stable within 0.1 K. Uncertainty analysis indicated that the trace humidity generator produces gas flows of constant humidity amounts with a relative expanded uncertainty less than 3.4% (k = 2) of the generated value. |
| Keywords: | Trace humidity Measurement Sensor calibration Water vapour permeation Polymeric tubes |
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