Abstract. There are several techniques available to generate humidity references by using stream of saturated gas with well-known water vapor content. Two-pressure humidity generator (2-P) is the most commonly used for the realization of temperature and relative humidity scales at National Institute for standards (NIS) and for disseminating traceability. This generator has been shown to be highly reproducible when properly used. In order to obtain traceable measurements and best performance, the temperature sensors and pressure gauges of this generator should be calibrated. This paper explained the calibration of 2-P temperature sensors and pressure gauges and the analysis of their performance for the first time at NIS.

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In the last ten years, there has been associate interest of makers and laboratories in having more accurate humidity measurements. Electrical relative humidity (RH) sensors have been widely used. These sensors need to be calibrated, and therefore the uncertainty measurement of these sensors has become a major concern. This paper describes the relative humidity uncertainty analysis and uncertainty contribution from saturator efficiency for the National Institute of Standards' (NIS-Egypt) two-pressure humidity generator. Efficiency tests were administrated. The saturator efficiency test results showed smart performance of the generator, as described below. Uncertainty analysis was also represented for all the sources that touch measurements. The expanded uncertainty of a coverage factor k=2 was found to be from ± 0.1% to ± 0.45% for relative humidity.