DEW-POINT MEASUREMENTS AT HIGH WATER-VAPOR PRESSURE

A dew-point meter capable of measuring humidity at high vapour pressur e and high temperature has been constructed and tested. Humidity measu rements in pure steam were made over the temperature range 100-150 deg rees C and a vapour pressure range of 1-4 bar. The dew-point meter per formance was assessed by comparing measurements with a pressure transm itter and agreement between the two was within +/-2.5% relative humidi ty. Humidity measurements in steam-air mixtures were also made and the dew-point meter readings were compared to those of a zirconia oxygen sensor. for these tests the dew-point meter readings were generally wi thin +/-2.5% relative humidity of the oxygen sensor measurements.