Testing the reliability of humidity generator through measurements traceable to calibration standards

This paper describes the metrological performance of NIS two-pressure humidity generator for testing the generator reliability after working for 13 years. In this work, humidity & temperature are observed and the measuring system is prepared for the calibration of humidity & temperature measurements. In the generator test chamber, relative humidity measurements are performed between 10% and 95% at fixed temperature of 25 degrees C and temperature measurements are performed between 10 degrees C and 65 degrees C at fixed humidity of 50% relative humidity. Results showed that the uniformity value is between +/- 0.13 degrees C and +/- 0.25 degrees C for temperature and between +/- 0.46% and +/- 0.62% for relative humidity. The value of stability is between 0.005 degrees C and 0.04 degrees C for temperature and 0.03% to 0.08% for relative humidity. Homogeneity value is in range between 0.09 degrees C and 0.12 degrees C for temperature, and between 0.43% and 0.52% for relative humidity, these satisfactory results showed the good performance of the generator. The expanded uncertainty of a coverage factor k=2 was found to be from +/- 0.2 degrees C to +/- 0.32 degrees C for temperature and +/- 0.8% to +/- 0.96% for relative humidity. The obtained results give us the confidence that NIS two-pressure humidity generator can be used as a high accurate humid air generator and reference instrument, for calibrating all types of dew-point meters and humidity sensors with high accuracy.