Calibration unit for gases

Claim 1

A calibration device for generating a gaseous mixture of known concentrations of oxidizing or reducing gases in an inert carrier gas comprising: an electrochemical cell for generating oxidizing and reducing gases, which includes a hollow body containing a first electrode and electrolyte, which electrolyte provides the ions that makeup the oxidizing or reducing gases; a second electrode at which the oxidizing or reducing gases are formed; an ion-exchange membrane which is disposed between and is in physical contact with the electrolyte and the second electrode, thereby permitting transfer of the ions forming the oxidizing or reducing gases through the ion-exchange membrane from the electrolyte to the second electrode while substantially containing the electrolyte in the hollow body; a porous membrane in physical contact with and separating the second electrode from a mixing chamber outside the electrochemical cell through which the oxidizing or reducing gases defuse into the mixing chamber; means for passing a known quantity of direct electrical current between the first and second electrodes to generate a known quantity of oxidizing or reducing gases; and means for passing a known quantity of inert carrier gas over the porous membrane in the mixing chamber to entrain the oxidizing or reducing gases in the inert carrier gas and generate a gaseous mixture having a known concentration.