Abstract
The measurement of absolute humidity of gases is essential in many industries. The effect of temperature on aluminum oxide and chilled mirror dew-point hygrometers is investigated. The temperature of laboratory, pipe line, and sensor is varied and the dew point is measured by two different aluminum oxide hygrometers. In all cases, the dew point of hygrometers is increased as the temperature is elevated. The reason behind this observation is due to desorption of water from the inside of pipe line and/or sensor surroundings at elevated temperature that result in the increase of the absolute humidity. Moreover, the sensor itself shows a certain degree of temperature dependency in sensing the humidity especially at low temperature. It is also studied that chilled mirror dew-point hygrometer may indicate a higher dew point than the reference at high temperature because the cooling capability of mirror is decreased at high temperature. Our study will provide evidences in the incorporation of the temperature effect as uncertainty factors in the standard calibration procedure for dew point hygrometers.
