What gases & chemicals should be avoided when using zirconium dioxide oxygen sensors?

This is week 9 of our weekly #SensorFAQs series which you can join in and follow on our twitter page.

We’ll be sharing Frequently Asked Questions we receive from our customers to help provide expert insights into our product range, the sensor industry and more.

This week we answer ‘What gases & chemicals should be avoided when using zirconium dioxide oxygen sensors?’

Details for next weeks #SensorFAQs:

Date & Time: Tuesday, 9th July 2019, 1.00pm GMT
Channel: #SensorFAQs

#SensorFAQs – Q9 | What gases & chemicals should be avoided when using zirconia dioxide oxygen sensors? pic.twitter.com/MBsPLAFYDN

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

Answers

#SensorFAQs – Q9 1/13 | Many oxygen sensors have cross sensitivity issues associated with them therefore it is important to know the root cause of the cross sensitivity in order to avoid environments that may pollute your zirconia dioxide oxygen sensor. https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 2/13 | There are specific gases and chemicals that have a negative influence on SST’s Zirconia Dioxide Oxygen Sensors, particularly on the life of the sensors or on the performance results. 📉 https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 3/13 | Combustible Gases 💥

Small amounts of combustible gases will be burned at the hot Pt-electrode surfaces or AI₂O₃ filters of the sensor. In general, combustion will be stoichiometric as long as enough oxygen is available… https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 4/13 | Combustible Gases 💥

…the sensor will measure the residual oxygen pressure which leads to a measurement error.

They aren’t recommended for applications where there are large amounts of combustible gases present. https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 5/13 | Gases investigated by SST are:

– H₂(Hydrogen) up to 2%; stoichiometric combustion
– CO (Carbon Monoxide) up to 2%; stoichiometric combustion
– CH₄ (Methane) up to 2.5%; stoichiometric combustion
– NH₃ (Ammonia) up to 1500ppm; stoichiometric combustion https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 6/13 | Heavy Metals ⚒

Vapours from metals such as Zn (Zinc), Cd (Cadmium), Pb (Lead), Bi (Bismuth) will have an effect on the catalytic properties of the Pt-electrodes.

Exposing the Zirconia Dioxide Oxygen Sensors to these metal vapours must be avoided. https://t.co/EJCtZ5JOsD

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 7/13 | Halogen and Sulphur Compounds

Small amounts (<100ppm) of Halogens and/or Sulphur compounds have no effect on the performance of the zirconia dioxide oxygen sensors… https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 8/13 | Halogen and Sulphur Compounds

…Higher amounts of these gases will, in time, cause readout problems or, especially in condensing environments , corrosion of sensor parts. https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 9/13 | Gases investigated by SST are listed below;

♦️ Halogens, F₂ (Fluorine), Cl₂ (Chlorine)
♦️ HCL (Hydrogen Chloride), HF (Hydrogen Fluoride)
♦️ SO₂ (Sulphur Dioxide)
♦️ H₂S (Hydrogen Sulphide)
♦️ Freon gases
♦️ CS₂ (Carbon Disulfide) https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 10/13 | Reducing Atmospheres ☁️

Long time exposure to reducing atmospheres may in time impair the catalytic effect of the Pt-electrodes and must be avoided… https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 11/13 | Reducing Atmospheres ☁️

…Reducing atmospheres are defined as an atmosphere with very little free oxygen and where combustible gases are present. In this type of atmosphere oxygen is consumed as the combustible gases are burned. https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 12/13 | Many customers get SST’s Zirconia Dioxide Oxygen Sensors confused with Bosch Lambda oxygen sensors that are mainly used in automotive combustion applications 🚗. https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

#SensorFAQs – Q9 13/13 | SST’s oxygen sensors were developed for boiler combustion control applications. Life tests have been performed in:

♦️ A laboratory atmosphere
♦️ Exhaust gases of natural gas fired boilers
♦️ Exhaust gases of light oil https://t.co/EJCtZ5sdB5

— SST Sensing Ltd (@SSTSensingLtd) July 2, 2019

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