Abstract

An oxygen ion conductive solid electrolyte electrochemical cell is employed to pump oxygen for combustible reaction with fuel constituents of a combustibles gas environment which diffuse through an aperture of a housing. The housing in combination with the solid electrolyte electrochemical cell forms an internal chamber. The EMF established across the electrodes of the solid electrolyte electrochemical cell pumps sufficient oxygen for complete combustion with the fuel diffusing through the aperture into the internal chamber. The resulting current of the solid electrolyte electrochemical is indicative of the rate of diffusion of the fuel or combustibles constituent through the aperture. The rate of diffusion is proportional to the fuel or combustibles content of the combustibles gas environment.An EMF measuring circuit connected to an auxiliary pair of electrodes associated with the solid electrolyte electrochemical cell are used to sense the condition wherein the atmosphere within the internal chamber changes between a reducing atmosphere and an oxidizing atmosphere. This EMF indication can be used to identify a predetermined level of pumping electrical potential at which variations in the solid electrolyte electrochemical cell current is indicative of the rate of diffusion of the fuel or combustibles constituent through the aperture.