Rapid, sensitive hydrogen detector with flow path difference compensation

A molecular hydrogen detector, comprising:

• an inlet configured to receive sample gas that includes ambient water vapor and hydrogen;
• a flow divider configured to divide the sample gas into a chemical conversion flow and a bypass flow;
• a first catalytic oven configured to chemically convert hydrogen in the chemical conversion flow to water vapor;
• one or more valves configured to alternately pass either the converted chemical conversion flow or the bypass flow;
• a gas dyer having a segment configured to alternately receive either the converted chemical conversion flow or the bypass flow and produce a modulated flow;
• a second catalytic oven configured to chemically convert hydrogen in the modulated flow to water vapor;
• a water vapor monitoring cell configured to measure water vapor in the converted modulated flow to produce a water vapor signal;
• and
• a processor configured to separate the water vapor signal into an ambient water vapor signal and a hydrogen-derived water vapor signal, and to output a hydrogen signal that is based on the hydrogen-derived water vapor signal to describe molecular hydrogen in the sample gas.

A molecular hydrogen detector, comprising:

• means for receiving sample gas that includes ambient water vapor and hydrogen;
• means for dividing the sample gas into a chemical conversion flow and a bypass flow;
• first means for chemically converting hydrogen in the chemical conversion flow to water vapor;
• means for alternately passing either the converted chemical conversion flow or the bypass flow;
• means for producing a modulated flow in which both differences in water vapor concentration between the chemical conversion flow and the bypass flow and hydrogen-derived water vapor produced by the first chemical conversion has been erased;
• second means for chemically converting hydrogen in the modulated flow to water vapor;
• means for measuring water vapor in the converted modulated flow to produce a water vapor signal;
• and
• means for separating the water vapor signal to extract a hydrogen-derived water vapor signal, and for outputting a hydrogen signal that is based on the hydrogen-derived water vapor signal to describe molecular hydrogen in the sample gas.