Influence of Humidity on Hydrogen Sensing Using a Quartz Oscillator

Abstract

  The influence of atmospheric humidity on the output of a quartz friction pressure gauge (Q-gauge) was investigated because the viscosity and molecular weight of water, which is the source of humidity, are significantly smaller than those of air; therefore, they affect the Q-gauge output. In the temperature range of 10-50℃, the nominal pressure from the Q-gauge decreased by approximately several percent owing to relative humidity, which was higher than the lower explosive limit of hydrogen, and this may cause an error in hydrogen sensing. The Q-gauge output was pressure-calibrated using its humidity dependence, and therefore, the difference in the pressure-calibrated Q-gauge output (Q-gauge ratio) between 0 and 100% humidity was reduced to 1% of the Q-gauge ratio. It was indicated that the influence of humidity can be excluded by calibrating the Q-gauge output using the humidity dependence necessary for the outdoor use of that type of hydrogen sensor.