4798 - An Experimental Evaluation of Duct-Mounted Relative Humidity Sensors: Part 2—Accuracy Results PDF

This is the second paper in a three-part series reporting on the test and evaluation of typical duct-mounted relative humidity sensors used in building HVAC applications. In this paper, three duct-mounted humidity sensors from each of six different manufacturers were tested and evaluated to determine the sensor accuracy and to provide a comparison with manufacturer specifications. A total of 18 sensors were tested, nine of them were capacitive-type sensors and nine were resistive- type sensors. The sensors were tested at three different temperatures (i.e., 15°C, 25°C, and 35°C) and five different relative humidity (RH) levels (i.e., 10%, 30%, 50%, 70%, and 90% RH). The experimental procedure used for testing and evaluating the accuracy of the humidity sensors was described previously in Part 1 (Joshi et al. 2004a) of this paper. The test and evaluation results show that at 25°C, two of the six humidity sensor models are within manufacturer-specified accuracy of ±3% for the entire relative humidity range of 10% to 90%. A third sensor model did not meet the manufacturer- specified accuracy of ±3% at any humidity level tested while the remaining three sensor models met the manufacturerspecified accuracy of ±3% for only part of the humidity range.