Performance characteristics of conventional oxygen gauges
Abstract The performance characteristics of oxygen gauges incorporating zirconia tubes from various suppliers were compared using tests developed in our laboratory. These tests were based on the coupling of an electrochemical oxygen pump with the gauge under examination. Systematic tests were performed in the 500–900°C temperature range in which oxygen gauges are most frequently used. Air was selected as a reference atmosphere and platinum as the electrode material. In an oxygen-pressure versus temperature diagram, each gauge can be characterized by a domain of ideal response, beyond which errors in oxygen-pressure measurements increase rapidly. The width of this domain was selected as a criterion for gauge comparison. Within the domain of ideal response, experiments were also performed to determine the degree of reproducibility of oxygen-pressure measurements and the accuracy which can presently be expected. An additional investigation was performed at high temperature (1000–1500°C) using a zirconia-tip electrode, to show the conventional effects of electronic conductivity. Extrapolation to medium temperature was compared to the experimental results of the systematic tests to estimate the magnitude of these effects under normal measurement conditions.