Overview Walsn Oxygen Analyzer is designed to measure the continuous oxygen concentration in combustion flue gases of boilers and furnaces. Walsn Oxygen Analyzer uses a non-sampling (wet) analysis method. It consists of detecting unit (oxygen probe) and control unit (transmitter). The flue mounted probe has a thermostatically controlled heated Zirconia oxide sensor located at the flue end of the probe. The control unit is designed for use with the Zirconia sensor type oxygen probe. The control unit offers a centralized termination for functions such as an automatic calibration box, external calibration contacts, status relay contacts and analog and serial outputs. Virtually no maintenance is required. Repair can be carried out quickly and simply: the internal components can be withdrawn from the probe and replaced as one unit. The probe will safely operate under start-up conditions for all conventional boiler fuels,provided the fuel ignition temperature is greater than 2003F. Measuring Principle Walsn Oxygen Analyzer contains a zirconia oxide sensing element, comprising a thimble-shaped zirconia cell fitted with inner and outer electrodes at its closed end. The inner electrode is exposed to the flue gas entering the open end of the cell; the outer electrode is supplied with air from a pump or regulator and is therefore exposed to a constant partial pressure of oxygen. Since zirconia is an electrolyte which conducts only oxygen ions at temperatures in excess of 600 F, the voltage generated between electrodes (i.e. the cell output) is a function of the ratio of the oxygen partial pressure on the inner electrode and its temperature. Therefore, any change in the oxygen partial pressure of the flue gas at the exposed electrode produces a change in the cell output voltage as dictated by the Nernst equation.