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Results of the collaborative study of TU-Darmstadt and PTB in the HIT project were presented at the final workshop at INRIM, Torino, Italy.

PTB has set up a system for the validation of dTDLAS-hygrom-eters which were developed by TU-Darmstadt within the frame-work of HIT. The calibration facility is designed to calibrate hu-midity in air measurement devices at temperatures up to 100 °C. The system was designed to perform validations and/or calibrations of a device under test like the dTDLAS-hygrometer from TU DA. Traceability was achieved by comparison to a pri-mary humidity standard via a reference chilled mirror hygrome-ter.

The developed dTDLAS hygrometer was shown to yield relative deviations of less than 5 % as compared to the reference value. This is nicely confirming its capability to be used as a transfer standard. Based on PTB’s validation result and on further vali-dation performed at INRIM for temperatures above 100°C the dTDLAS hygrometer could subsequently be applied success-fully at an industrial site within the project thus demonstrating the valuable capabilities of such dTDLAS systems for industrial applications.

The measurement approach of dTDLAS-hygrometers comply-ing with the TILSAM method 1 like the one from TU-Darmstadt in HIT is promoted by PTB 3.42.