This utilizes the fact that Oxygen is a paramagnetic gas which distinguishes oxygen from other gases because it is attracted into a strong magnetic field. Basically when a gas sample is introduce to the instrument the oxygen will be drawn into the magnetic field resulting in a change in the flow rate. The flow rate change is proportional to the oxygen concentration of the sample gas. Paramagnetic analyzers may be used for measurement of oxygen at any level between 0-100%.
Advantage of paramagnetic types O2 analyzer are :Capable of measuring flammable gas mixtures that cannot be measured by a zirconia oxygen detector with its heated cell. A paramagnetic system offers the fastest response time and is more resistant to vibration or shock.
Disadvantage of paramagnetic types of O2 analyser are :Some other gases, such as N2O, CO2, or NO2, are also paramagnetic and their presence in the gasstream can cause a false reading. Because of the sample system the response time is slow, sometimes up to 30 seconds or more.Require accurate temperature conditioning of detector and sample. Accurate flow and pressure control of the sample and auxiliary gas is needed. This method is also sensitive to fluctuations of ambient conditions, vibration and mechanicalagitations, variations in background gases and detector drift.