| ENOTEC has resolutely put the Nernst equation into practice for the user's benefit. The Nernst equation and its "leak-tight fraction line". A process gas (A) with an unknown oxygen (02) concentration flows around the outside of a measuring probe which is sealed off to the process gas by means of a heated zirconium-oxide measuring cell (B). A reference gas (C), with a known oxygen (02) concentration, flows to the inside of the measuring cell. At an optimum temperature a voltage (U) in mV is created between the two surfaces of the cell. At a constant temperature in the cell this voltage is dependent only on the ratio of the oxygen concentrations (partial pressures) in (A) and (C). Using air (oxygen content at constant 20.95%) as a reference gas, the measured voltage is a direct measure of the oxygen concentration in the process gas (A), provided that the isolation between the process gas and the reference gas is absolutely gas-tight, thus ruling out distortion of the resulting measured value. |