Evaluation of measurement uncertainty of humidity standard device based on chilled-mirror dew-point hygrometer

High precision dew-point hygrometer is a high accurate surveying instrument and the general transfer standard for national humidity value and international comparison.Two-pressure humidity generator is also a standard device of transferring humidity value,which can output humidity gas continuously.Many factors of measurement uncertainty appeared in standard device are discussed,when high precision dew-point hygrometer and two-pressure humidity generator are running together.From the working principle of two-pressure humidity generator,the mathematical model is established and measurement uncertainty of humidity standard device is evaluated by the dew-point temperature unit.