Gas sensors are invaluable tools in various industries for detecting hazardous and combustible gases in the air. However, not all gas sensors are made equal. In this post, we will compare two popular types of gas sensors- catalytic and semiconductor.
Catalytic Gas Sensors
Catalytic gas sensors, also known as combustion sensors, work based on the principle of catalytic oxidation. In catalytic gas sensors, a catalyst material is heated to a high temperature, typically above 500°C. When a flammable gas comes in contact with the catalyst, it reacts, producing heat and raising the temperature of the catalyst. The increase in temperature is measured and detected as a change in resistance, providing an indication of the presence of flammable gases.
Catalytic gas sensors are highly reliable and accurate, with a sensitivity range from 0 to 100% of the lower explosive limit (LEL) of a gas. They are commonly used in combustible gas detection systems, such as those found in refineries, petrochemical plants, and gas pipelines.
However, catalytic gas sensors have some limitations. They require a continuous flow of electricity to maintain the high temperature of the catalyst material, which can consume a considerable amount of power. Additionally, they can be susceptible to poisoning from certain gases, such as silicones and lead compounds.
Semiconductor Gas Sensors
Semiconductor gas sensors work based on the principle of gas absorption. In semiconductor gas sensors, a thin layer of semiconducting material is used as the sensing element. When a gas molecule is absorbed onto the surface of the material, it changes the electrical conductivity of the semiconductor, which can be measured as a change in resistance.
Semiconductor gas sensors are highly efficient, low-cost, and can detect a wide range of gases with high sensitivity. They are commonly used in residential and commercial gas detectors, such as those for carbon monoxide (CO), nitrogen dioxide (NO2), and hydrogen (H2).
However, semiconductor gas sensors have some limitations as well. They can be affected by humidity, temperature, and other environmental factors, which can affect their accuracy. Additionally, their lifespan can be shorter than that of catalytic gas sensors due to the possibility of the semiconductor material degrading over time.
Which One Should You Choose?
Choosing between catalytic and semiconductor gas sensors depends on the specific application and conditions of use. If you require high accuracy and reliability in detecting combustible gases in a harsh environment, a catalytic gas sensor may be the better option. However, if cost, versatility, and low power consumption are more important concerns, a semiconductor gas sensor may be a better choice.
In conclusion, both catalytic and semiconductor gas sensors have their pros and cons. It is crucial to understand the principles of operation, advantages, and limitations of each type before making a purchase decision.
References
- Ruffin PB, et al. Fiber optic catalytic and thermal sensors for detection of combustible gases. Proc. SPIE 2836, Chemical, Biochemical, and Environmental Fiber Sensors VIII, 333 (November 10, 1996); doi:10.1117/12.257199.
- T. Seiyama, K. Kato, A. Fujiishi, and M. Nagatani. A New Detector for Gaseous Components Using Semiconductive Thin Films. The Journal of Chemical Society, Vol 51, Page 2, 1983.