Issues with measurement errors of oxygen analyzers
Thread Content
The oxygen analyzer (DHY-102C) from Beijing Beifen Mahack gives correct readings when calibrated with standard gas, but shows incorrect values when using process gas. The actual oxygen content is around 0.2%, yet the measurement result is around 0.04%. What is the cause of this issue?
Usage location? Sample components? Is the instrument electrochemical?
It is an electrochemical measurement method; at the outlet of the gas tank, the composition is: CO: 28-32%, O2
Ensure that the pretreatment of the sample gas is proper, such as dust removal, water removal, cooling, etc. If there are any further issues, one can only consult the manufacturer.
The reference gas is likely to be a single gas, while your process gas is a mixed gas; it is recommended to use a mixed gas for calibration. We have encountered such problems with our online instruments. Interfering gases are likely to be present in the process gas. Take another look to see if there is temperature and pressure compensation
Check the sample’s preprocessing section to see if there are any blockages or leaks.
It might be due to impurities such as H2S; H2S can easily cause the battery to become poisoned, so it’s necessary to thoroughly investigate the issues related to preprocessing
How did you solve it?
We have dealt with similar issues where online and manual analyses do not match. Only ideas and possibilities are provided; specific issues should be analyzed on a case-by-case basis
Our site is similar as well. The sample gas contains components such as CS2 and H2S (protected by N2); it is calibrated using standard gases, and the reaction sensitivity is normal ； Calibrating and measuring the sample gas with air results in a very slow reaction!
I think there’s an issue with the selection of your instruments themselves. It is likely caused by interference from the gas background atmosphere; you can look for the cause in that direction, or try using a gas with components identical to those of the sample gas’s background atmosphere as a calibration gas.