Datasheet: Model 499A Trace Dissolved Oxygen Sensor

The Model 499A TrDO sensor is intended for the determination of trace (ppb) levels of dissolved oxygen in steam power plants and high purity cooling water.

The 499A TrDO is a membrane-covered amperometric sensor. The sensor consists of a gas-permeable Teflon1 membrane stretched tightly over a gold cathode. A silver anode and an electrolyte solution complete the internal circuit. During operation, oxygen diffuses from the sample through the membrane to the cathode. A polarizing voltage applied to the cathode converts all the oxygen entering the sensor to hydroxide ions. The reaction produces a current, which the analyzer measures. The current is directly proportional to the rate at which oxygen reaches the cathode, which is ultimately proportional to the concentration of oxygen in the sample.