WHAT TO CONSIDER WHEN SELECTING AN O2 ANALYZER

Selecting the most appropriate O2 analyzer to use depends on a number of factors such as environmental conditions and desired accuracy. Some instruments are able to measure very small traces of oxygen while others are most suitable for larger concentrations. The principle of operation for different analyzers also varies. The most common types of instruments used to measure O2 concentration are Zirconia analyzers and paramagnetic analyzers. Their names can evidently tell the principle used to measure oxygen. Each one of them has its strengths and weaknesses as well. A brief study of their operation might help in making a suitable selection.

The paramagnetic O2 analyzer works on the principle that the effect of magnetism on oxygen molecules is larger than in other gases. Therefore, other gases are neglected during analysis. The main chamber consists of two spherical glasses with different magnetic susceptibility. Oxygen molecules are passed between the balls and are attracted towards the sphere with a stronger magnetic field. This leads to a deviation that is recorded by a light sensor. The extent of deviation is used to determine the concentration of oxygen gas. A special advantage of this method is that no heat is used or produced during the process.

The zirconia O2 analyzer on the other hand makes use of a zirconia ceramic unit. The conductivity of this material is used to determine the concentration of oxygen gas. In this method, the sample gas and reference gas are placed on either sides of the ceramic wall. The wall allows for oxygen molecules to pass through under high temperature. Oxygen ions move from the region of high concentration to low concentration. This movement generates an EMF that is measured to define the oxygen content of the sample. This method is very accurate for measuring low concentrations as well as high concentrations of oxygen.

The best O2 analyzer to use will depend on a number of factors. The first consideration is whether there are other flammable gases in the sample. Since the paramagnetic analyzer does not generate any heat, it is most suitable for measuring flammable samples. Otherwise, the zirconia type is best suit for very accurate results. Various precautions should be taken when using these instruments. The manufacturers usually include precautions in their user manuals. They state the best conditions under which the instrument can be used and cases that may lead to damage of various components. All these factors should be considered when using the O2 detectors.