Temperature calibration of quartz oscillator for outdoor hydrogen sensing

For outdoor hydrogen sensing using a quartz friction pressure gauge (Q-gauge), we investigated the influence of ambient temperature on the output from a Q-gauge, because the change in the baseline of the Q-gauge output might be comparable in degree to the changes resulting from hydrogen leakage, which results in an error for hydrogen sensing. At constant relative humidity, the output from the Q-gauge changed with the change in temperature within the range 15-50 °C. The largest differences in the output with respect to temperature corresponded to those seen in hydrogen leakage with about 6 vol% hydrogen concentration, judging from the correlation between the change in the Q-gauge and hydrogen concentration. 6 vol% hydrogen concentration is clearly higher than the necessary minimum for detection of hydrogen concentration because one-fourth of the low explosive level hydrogen concentration is 1 vol%; therefore, temperature calibration is necessary for outdoor use of this hydrogen sensing method. We tried to suppress the influence of temperature on the Q-gauge output using the temperature dependence of the experimental output. We found that the influence of temperature could be reduced to change the output by less than 1 vol% hydrogen concentration.