New analytical method for measurement of hydrogen partial pressure using a tubular hydrogen pump-gauge

A tubular hydrogen pump-gauge was constructed and applied to measure hydrogen partial pressure by using a new analytical equation. The merit of using the equation is that a reference gas with a known hydrogen partial pressure is not necessary; in fact, the method worked well when the reference gas was Ar/H-2/H2O or air/H2O. Sample gases, containing up to 1% by volume hydrogen in argon and including water vapor, were flowed through a non-porous tube of a proton conductor operated at temperatures in the range 700-800 C. Current was passed via one pair of porous platinum electrodes to pump hydrogen electrochemically in or out of the gas flowing in the tube. A second pair of electrodes downstream enabled a Nernst emf to be monitored. Passing a current, 1, resulted in a change in Nernst emf, Delta E. A new theoretical equation predicted a linear relationship between exp(-2F Delta E/RT) and I at constant gas flow rate within the tube, and also between exp(-2F Delta E/RT) and the reciprocal flow rate at constant l. Measurements validated these predictions at hydrogen partial pressures up to 5 x 10(-4) atm.