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 ℃to 0 ℃. The air flows through a ...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 ℃to 0 ℃. 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℃ to -4- 0.15℃ 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.展开更多
A new humidity calibration facility using a 2-T （two-temperature）, constant pressure principle for generating gas of known humidity has been developed at NIS for primary realization of relative humidity scale in the...A new humidity calibration facility using a 2-T （two-temperature）, constant pressure principle for generating gas of known humidity has been developed at NIS for primary realization of relative humidity scale in the range from 13% to 98% for calibrating and testing hygrometers to improve the uncertainty. This paper reports the construction of the 2-T humidity generator describing its saturator and the test chamber system. Results of the efficiency tests of its saturator showed satisfactory generation performance for a primary realization of relative humidity scale. The expanded uncertainty of the relative humidity with a coverage factor k = 2 was found to be from ± 0.25 % to ± 0.67%.展开更多
Abstract： This paper describes the development and characterization of a two-temperature （2-T）, constant pressure humidity generator It relies on the saturation of a stream of gas flowing over a water surface maint...Abstract： This paper describes the development and characterization of a two-temperature （2-T）, constant pressure humidity generator It relies on the saturation of a stream of gas flowing over a water surface maintained at constant, well-known, temperature. It was built in order to improve the uncertainties of the dew-point temperature and humidity scales realization at the National Institute for Standard （NIS） in the dew-point range from -50 ℃ to ＋ 10 ℃. Several experiments were carried out in the above mentioned range in order to characterize the generator. Characterization comprised studies of its saturator efficiency, temperature stability and a comparison with a calibrated chilled-mirror hygrometer. The results of the efficiency tests showed good performance of the generator as described below. For uncertainty of measurements, a thorough analysis was also described representing estimations of contributions for all the sources that affecting measurements.展开更多
文摘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 ℃to 0 ℃. 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℃ to -4- 0.15℃ 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.
文摘A new humidity calibration facility using a 2-T （two-temperature）, constant pressure principle for generating gas of known humidity has been developed at NIS for primary realization of relative humidity scale in the range from 13% to 98% for calibrating and testing hygrometers to improve the uncertainty. This paper reports the construction of the 2-T humidity generator describing its saturator and the test chamber system. Results of the efficiency tests of its saturator showed satisfactory generation performance for a primary realization of relative humidity scale. The expanded uncertainty of the relative humidity with a coverage factor k = 2 was found to be from ± 0.25 % to ± 0.67%.
文摘Abstract： This paper describes the development and characterization of a two-temperature （2-T）, constant pressure humidity generator It relies on the saturation of a stream of gas flowing over a water surface maintained at constant, well-known, temperature. It was built in order to improve the uncertainties of the dew-point temperature and humidity scales realization at the National Institute for Standard （NIS） in the dew-point range from -50 ℃ to ＋ 10 ℃. Several experiments were carried out in the above mentioned range in order to characterize the generator. Characterization comprised studies of its saturator efficiency, temperature stability and a comparison with a calibrated chilled-mirror hygrometer. The results of the efficiency tests showed good performance of the generator as described below. For uncertainty of measurements, a thorough analysis was also described representing estimations of contributions for all the sources that affecting measurements.
