NIS PRIMARY DEW/FROST-POINT GENERATOR OPERATING FROM-50 °C TO 0 °C IN DEW POINT TEMPERATURE

摘要

This paper describes construction and characterization of a dew/frost -point generator developed at national institute for standards. It is intended to operate in the range from -50 °C to 0 °C. The air flows through a saturator controlled by a regulated flow meter. The reference dew/frost -point temperature was measured by Standard Platinum Resistance Thermometer (SPRT) connected to a resistance bridge. A comparative study between the saturator temperature of the new generator measured by SPRT and the dew/frost-point temperature of a calibrated chilled-mirror hygrometer was conducted. It helped to determine the uncertainty of saturator; this uncertainty was found to be between ± 0.06 °C to ± 0.15 °C at confidence limit of 95%. Several experiments were carried out in the mentioned range. Obtained results gave the confidence that NIS generator could be used as a primary humid air generator.