HUMIDITY GENERATOR FOR COMPARISON CALIBRATION PURPOSE

Abstract − This paper presents a facility for humid air generation – the humidity generator. The generator was developed for calibration of hygrometers. The principle of operation is based on the two-temperature method for humid air generation and the open circuit flow mode is applied. Saturation of the air is achieved by the water atomization in air flow. The generator is designed to operate in the test chamber temperature range from 5 °C to 85 °C and in dew point temperature range from 2 °C to 35 °C. The paper makes a point to the possibility the system works in nonsaturation mode and the comparison method is applied for calibration purpose. The excellent dynamic characteristics are obtained by the fast changes of the quantity of water dispersed in air flow. Maintenance the intensity of the atomization and stationary temperature at the same time enables stationary air humidity circumstances in the test chamber. Dynamic and stationary characteristics of generator, as well as uniformity working area inside the test chamber is numerically and graphically presented. Analysis of the uncertainty using comparison calibration method is also reported. The software developed in LabVIEW environment supervises the system operation