Basic principles of gas detection in oil

From the detection principle, the gas sensors for online gas detection can be roughly divided into three categories: gas sensors, thermal conductivity cells and infrared optical sensors. Gas sensors include field effect tubes, semiconductor sensors, electrochemical sensors, etc. Mechanistically, they all convert gas content signals into electrical signals directly or indirectly through some action mode (generally chemical reaction). The manufacturing process of thermal conductivity cells may vary greatly, but they all derive gas content signals based on the effect of gas thermal conductivity on resistance.

The infrared optical sensor consists of a spectrometer and an infrared detector. It can identify the type of gas based on the different characteristic absorption frequencies of the gas and determine the gas content based on the absorbance at the characteristic frequency.

2.1 Gas separation method
Selective permeable membranes can only allow certain characteristic gases to pass through while preventing other gases from passing through. For example, some membranes are very favorable for hydrogen permeation, but have extremely low permeability to other gases, and can be used for single hydrogen monitors.

2.2 Selective sensitivity of sensors
The selective sensitivity of sensors can be used to make single gas monitors that are mainly sensitive to a certain gas and have a certain degree of sensitivity to several other gases.