Paramagnetic O2 Analyzer
There are a number of ways to measure O2 and depending on the application, that will decide how you are going to measure it. On our boilers we have an O2 for CEMS and two O2 for the control of the boilers and those are InSitu. The O2 for the CEMS is a paramagnetic and the in-process O2 are Zirconium Oxide. When someone says InSitu, it is measuring the process directly. It’s off in the stuff. Other analyzers are not in the process, we bring the sample to them. Well let me rephrase that. We pull the sample out of the process, normally with a sample probe and we pull it with a sample pump or an aspirator and not always but a lot of the time send it through a chiller and knock out any moisture and then run it through a couple of filters and then through a flow drawer and then to the analyzer. So we basically clean it up and send it to our analyzer. After we explain the paramagnetic O2, you will see why we do this.
The paramagnetic O2 is used everywhere. It is one of the most reliable machines out there and not hard to work on, user friendly and just a favorite choice for every time you can use one. The way that it works is very cool too. O2 is attracted to a magnetic field more than anything else out there. So it has an attraction rating of 100. Where N2 has a rating of 0. We will take advantage of this principle to measure the O2. We will place a magnet around a cell and this creates our field to attract the O2 and then we will place a dumbbell in this field with blown glass ends on each end (filled with N2) with a mirror in the middle. It is balanced on an axis. As the flow enters the cell, any O2 will want to hang out in the magnetic field and thus unbalancing our dumbbell. We have a fixed light source that is shining a beam of light at the mirror and then being reflected back to a photocell which will say how much O2 we have. This is really easy to understand and if taken care of properly will repeat day after day. This analyzer does not like it if moisture gets in there or dirt. In the event that you have some trash get in yours or liquids, place N2 on it and try to dry it out and clean it up. They are very delicate though and you can blow the dumbbell off of its axis. Then you have to replace the cell. When you go to replace the cell, you will need some non magnetic tools or you will be fighting this for a while.
The magnetic susceptibility of different gases.
Acetylene C2H2 ___________-0.24
Ammonia NH3 ___________-0.26
Argon Ar _________________-0.22
Carbon dioxide CO2 ________-0.27
Carbon monoxide CO _______+0.01
Hydrogen H2 ______________+0.24
Methane CH4 _____________ -0.2
Nitric oxide NO ____________+43.0
Nitrogen N2 _______________0.0
Nitrogen dioxide NO2_______+28.0
Oxygen O2 _______________100.0