Oxygen Analyzers – Paramagnetic and Zirconium Oxide O₂ Measurement

An oxygen analyzer determines the O₂ content of a gas stream – in percent by volume in the flue gas of a combustion process, in ppm in inert gas monitoring. What decides suitability and running cost is not the housing but the measurement principle: it sets the range the instrument covers, how hot and how loaded the sample gas may be, and how often it has to be calibrated or replaced. Choosing an O₂ analyzer therefore means choosing the principle first.

Three principles are common in industry. The paramagnetic sensor exploits the fact that oxygen is one of the few gases attracted by a magnetic field; it needs no chemical consumable and delivers the highest accuracy. The zirconium oxide sensor works inside a heated ceramic cell, tolerates hot flue gas and responds quickly, but reacts sensitively to combustible components in the sample gas. The electrochemical cell is the least expensive option and therefore widespread in portable instruments – it is a wear part and is replaced at fixed intervals. Fresenius Instruments builds the first two principles, as a single-gas instrument and as a channel in the multi-gas analyzer.

Oxygen is the most frequently measured gas component in industry – and the choice of the right measurement principle determines accuracy and application range. Fresenius Instruments offers two proven sensor variants with the GA210 O₂: the paramagnetic sensor exploits the unique magnetic property of O₂ molecules and achieves accuracies of ±0.05 vol.% – the optimum for CEMS installations, laboratory applications and quality control in the food and pharmaceutical industries.

The zirconium oxide variant (ZrO₂) of the GA210 O₂, by contrast, operates at high temperatures and is particularly suitable for direct measurement in exhaust gas streams from combustion plants, blast furnaces and thermal processes. Its advantage: fast response time and robustness against aggressive gases – ideal for combustion control, where fractions of a second determine efficiency and pollutant output.

Both GA210 O₂ variants are single-gas devices, each optimized for their specific application. For measurement tasks where oxygen must be monitored together with other gas components, the GA220 multi-gas analyzer provides the solution: it combines paramagnetic or ZrO₂-based O₂ measurement with NDIR channels for CO₂, CO, SO₂, NO and electrochemical sensors – up to 8 sample gas inlets in a single 19-inch rack housing.

All Fresenius Instruments O₂ measurement devices operate with patented automatic zero-point correction without test gas. This saves ongoing costs for calibration gases and ensures long-term stable measurement results. With over 30 years device lifespan, 10+ years spare parts guarantee and the Cloud Connect Kit for remote monitoring, you invest in O₂ measurement technology that works reliably for decades.