When selecting a sensor, although the type of technology it uses is important, there are a number of other considerations that must be taken into account. Several questions must be answered, and based on the answers, the user will have to decide what sensor provides the best compromise for the situation. A particular sensor will typically excel at one area, while rendered limited in a different area. Here are the right questions to ask:
Choosing the right oxygen sensor for your gas analysis application is imperative. With multiple configurations to choose from, paired with the right technology, and ensuring proper use with gases or liquids; it can be a confusing process. Bacharach’s Gas Analysis Experts compiled this article to help you make the right decision based on your needs.
Sensing technology, by far, is a leading factor when choosing the right oxygen sensor. They can be separated based on their principle of operation, such as Optical, Paramagnetic, Eletro-Chemical, and Zirconium Oxide. The following summary outlines the differences in technology for the different sensors:
|Optical:||LED light hits a membrane coated with luminescent dye. The dye will shine dimmer as the concentration of oxygen increases. An optical filter can measure the amount of light emitted and provide a value corresponding to the oxygen level.|
|Paramagnetic:||Two glass spheres filled with nitrogen are aligned in a strong magnetic field. When they are exposed to a gas containing oxygen, the spheres are pushed out of alignment by an amount proportional to the amount of oxygen in the sample.|
|Electro-Chemical:||An anode/cathode pair is submerged in an electrolyte solution. When oxygen in a sample galvanically reacts with the anode, it produces an electrical current proportional to the level of oxygen in the sample.|
|Zirconium Oxide:||A Zirconium Oxide probe, coated on opposite ends with platinum, is heated to about 650°C. At this temperature, the probe becomes porous, allowing oxygen to travel from a high to a low concentration, producing a voltage proportional to the difference in concentration. When placing the probe between air and a sample gas, for example, the difference in concentration can be calculated based on the voltage generated.|