FCX-MC-HT300-CH: High process temperature oxygen gas sensing
Amperometric, zirconia based oxygen sensors have many advantages over amperometric, liquid based electrochemical oxygen sensors. Long operational lifetime & signal stability of the zirconia oxygen sensors are some of the advantages, when the two types of sensors are benchmarked against each other, but also the ability of the zirconia sensor to measure oxygen concentrations in high temperatures up to 350°C is a distinct advantage that can be used in many applications. A combined high-temperature dryer/de-oxidation purifier of gases is an example of an application requiring oxygen control at elevated temperatures. Pewatron has developed solutions for the sensor front-end that allow operation up to 300°C in industrial processes.
The FCX-MC-HT300-CH sensor module consists of a HT300 sensor front-end and a MC sensor electronics connected by a high temperature cable. The MC sensor electronics accurately controls the temperature of the sensor element and also amplifies the sensor low-current signal into a 4-20 mA output signal (MC standard configuration). The HT300 sensor front-end is designed for operation in temperatures up to 300°C by using special processes and materials. The HT300 sensor front-end is individually calibrated at a high temperature (Ta) specified by the customer and the operation and tolerances of the sensor front-end are checked in a temperature tolerance band of Ta+/-50°C.
The oxygen sensing element, i.e. the amperometric zirconia oxygen sensor, can be chosen from 4 different measurement ranges; 0…1000 ppm, 0…5 %Vol, 0…25 %Vol & 0…95 %Vol. The choice of the sensor element depends on the exact application; for high-temperature drying & de-oxidation processes the 1000 ppm and 5 %Vol are popular choices, because these element high both have high signal resolution in low-oxygen concentration environments. For high temperature drying processes in atmospheric conditions or high-oxygen concentration environments, the 25 %Vol and 95 %Vol, respectively, are the best choice of sensor element. The 25 %Vol and 95 %Vol are diffusion flow limited type gas sensor, which means that they are independent of the total pressure in the systems. The response is dependent on the partial pressure of oxygen, which means that for > 100°C, the sensors can also measure absolute humidity.
The MC electronics is an OEM electronics with the possibility of chosen between analog (4-20 mA) and digital output (RS232/RS485 & I2C). For analog output, the modules can be adjusted and checked using a display box, where also the process parameters can be slightly adjusted in order to obtain maximum accuracy in a customer defined working point. The OEM electronics can be delivered in metal enclosure for easy integration into existing electronic mounting racks.
