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

Abstract

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 °C and temperature measurements are performed between 10 °C and 65 °C at fixed humidity of 50% relative humidity.Results showed that the uniformity value is between ±0.13 °C and ±0.25 °C for temperature and between ±0.46% and ±0.62% for relative humidity. The value of stability is between 0.005 °C and 0.04 °C for temperature and 0.03% to 0.08% for relative humidity. Homogeneity value is in range between 0.09 °C and 0.12 °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 °C to ±0.32 °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.