Method for determining relative amount of oxygen containing gas in a gas mixture

A method employing an electrochemical oxygen pumping device for measuring the relative amount of a measurement gas consisting essentially of at least one oxygen containing gas in a gas mixture comprising in addition at least a second oxygen containing gas which is capable of being pumped out of said device or disassociated at a voltage less than that which is capable of disassociating said measurement gas, said method comprising the steps of:

• providing communication between said gas mixture and a first porous layer of an electrochemical device, which device comprises;
• a generally planar first electrochemical oxygen pump cell including a relatively dense platelet with one of a pair of porous electrodes on each of two spaced sides of said platelet, one of said porous electrodes being exposed;
• the first porous layer deposited on one of the electrodes of said first pump cell;
• a generally planar second electrochemical oxygen pump cell including a first porous electrode, a second porous layer and a second porous electrode deposited successively on said first porous layer;
• applying and maintaining a first voltage across said second pump cell to positively bias said second electrode (i) sufficiently to cause substantially all said second oxygen containing gas molecules inside said first porous layer to be pumped out or disassociated by a current flowing through said second pump cell and (ii) insufficiently to disassociate said measurement gas;
• applying and maintaining simultaneously with the maintaining of said first voltage, a second voltage across said first pump cell to positively bias the exposed electrode of said first pump cell sufficiently to disassociate only substantially all of said measurement gas molecules inside said first porous layer;
• and
• measuring said current flowing through said first pump cell, said current being proportional to the relative amount of said measurement gas in said gas mixture.