Failure prediction for a galvanic oxygen sensor

Electrochemical oxygen sensors are widely used for industrial hygiene applications to monitor potentially dangerous conditions due to oxygen deficiency or excess. Oxygen sensors of the galvanic type operate by consumption of an internal, easily oxidizable anode. Once the entire anode has been consumed, the sensor will no longer respond to oxygen and this failure of the sensor is often rapid and with little warning. This paper describes an electrical test, consisting of measuring the ratio of the steady state current at an applied potential of ∼0.4 V vs. the steady state current at 0 V. A ratio close to unity indicates that the sensor is functioning normally, whereas a ratio much less than unity indicates that the sensor will fail soon. This test may be performed in situ on the oxygen sensor by a gas detection instrument, which provides a means for the detection of an imminent failure, while the sensor is still operational.