PECM Issue 58 2022 | Page 146

Monitoring O2 Levels with Zirconia Oxygen Sensors


Monitoring O2 Levels with Zirconia Oxygen Sensors
In many industries , there is a continuous requirement to monitor oxygen levels . In some applications it is necessary to reduce oxygen in a controlled atmosphere such as food storage and transportation . This prolongs the life of perishables . Other applications include suppressing oxygen levels in aircraft fuel tanks to eliminate the possibility of explosion or fire , reduce pollution and harmful gases in industrial plants , maximize efficiency saving fuel costs , and reduce emissions in industrial boilers . Process Sensing Technologies ( PST ) has a range of zirconium dioxide oxygen sensors , manufactured by one of its leading brands SST Sensing Ltd . These highly robust sensors come with different steel housing styles , cabling , and electrical connection options to meet many of these application requirements .
PST Zirconia Oxygen Sensors come standalone or with integrated electronics offering digital or analogue industry standard outputs . Unlike other technologies , their long operating life is due to the non-depleting sensor cell technology . No reference gas is required , and easy single point calibration can be performed in fresh air . Their ability to function in wide oxygen measuring ranges , operating temperatures and high-pressure environments results in a rugged , robust , and reliable sensor that is RoHS compliant . The oxygen sensors can measure over a wide oxygen range ( 0.1 to 100 % O₂ ).
Zirconia oxygen sensors from PST use a unique closed-loop measurement system . While the sensor continuously measures the oxygen level , a heartbeat signal is also generated , providing an immediate warning of any failure .
The sensors are constructed with a domeshaped block of Zirconium dioxide ( ZrO2 ), coated on the inner and outer sides with a thin-porous platinum layer . The Zirconium dioxide acts as a solid electrolyte and is doped with yttrium oxide , which enhances the thermal and mechanical stability and electrical characteristics .
Unlike other technologies , their long operating life is due to the non-depleting sensor cell technology .
The platinum porous layer acts as an electrode , allowing oxygen ions to pass through into the ZrO2 electrolyte . One side of the assembly is exposed to the sample gas , whereas the other side is exposed to a reference gas ( typically air ).
PST can also supply an interface board that provides the necessary electronics to power and control the zirconia oxygen sensors , as well as a complete oxygen measurement system such as the PST OXY-FLEX . When choosing the most appropriate option , customers should consider the O2 measurement range required and what the output requirement is i . e ., digital ( RS485 Modbus or RS232 ) or analogue ( 4 – 20mA or 0 – 10VDC ). Other considerations are the cable length to maintain the correct sensor heater voltage and minimize noise pickup . PST recommends keeping the cable length between the sensor and interface board as short as possible .
Zirconia Sensor Probe Series - Screw Fit Housing
Flange mounted Zirconia Sensor
ZrO2 Miniature Zirconia Sensor
For more information , please visit ProcessSensing . com
146 PECM Issue 58