Bilateral comparison in dew-point temperature

Project Description

Since 2003 the company E+E Elektronik Ges.m.b.H. is authorised by Bundesamt für Eich- und Vermessungswesen (BEV) to hold the Austrian national reference for gas humidity. With reference to this decision there exists great mutual interest to compare the national references for humidity. A dew point hygrometer is to be used as transfer standard for the comparison in the range from -20 °C to +65 °C dew point temperature.

Final Report 2005-03-18

Since 2004 E+E Elektronik Ges.m.b.H in Engerwitzdorf, Austria, is maintaining the Austrian national standard for humidity on behalf of BEV - Bundesamt für Eich- und Vermessungswesen, Vienna, Austria. In order to ensure measurement capability and accuracy this bilateral comparison with PTB has been set up. The measurements have been carried out using a chilled mirror hygrometer as transfer standard. The humidity generators at both partners were two-pressure national standard generators.

Five dew- / frostpoint temperatures have been measured by both partners. Each dew- / frostpoint temperature has been realized by three different sets of pressure / temperature values. Each set of pressure / temperature values have been measured at least two times. The results were obtained by recording the resistance of the second Pt-100 PRT of the transfer standard at a measuring current of 1 mA with a resistance bridge. The resistance values have been converted into temperature values using an equation similar to IEC 60751 with individual calibration coefficients for the Pt-100 PRT. The deviations from the reference value recorded in the following table are the mean values for each dew- / frostpoint. From the deviation and the associated expanded uncertainty of each partner the normalized error En was calculated and recorded in the table.