Proven measurement principle: NDIR sensors from smartGAS

In non-dispersive infrared absorption (NDIR), the property of gas molecules is utilized to absorb infrared radiation at specific wavelengths. (Image: smartGAS)

smartGAS has been developing and producing reliable, precise, and economical non-dispersive infrared absorption sensors (NDIR) for gas detection in a wide range of applications for 15 years. The sensors from smartGAS are extremely low-maintenance, durable, and can be individually tailored to each application. NDIR gas sensors are suitable for highly accurate measurement of a variety of gases and make an important contribution to industrial process safety and control, as well as to occupational and environmental protection.

Non-dispersive infrared absorption (NDIR) utilizes the property of gas molecules to absorb infrared radiation at specific wavelengths. Each infrared-absorbing gas has a specific absorption spectrum and thus an individual fingerprint with characteristic peaks in the infrared spectrum. The higher the concentration of the respective gas, the more infrared radiation it absorbs. An infrared detector registers the reduced light intensity of the radiation and converts it into a signal indicating the existing gas concentration. An interference filter, pre-selected and adapted to the respective gas, prevents the detector from responding to wavelengths outside the spectrum of the gas to be measured.

In practical application, an electrically modulated radiation source sends infrared radiation through a measurement cell, known as a "cuvette." The gas to be measured is introduced into the cuvette and is traversed by the infrared radiation, with a portion of the radiation absorbed by the gas. At the other end of the cuvette, the reduced light intensity of the radiation is registered by an infrared detector and converted via a measurement amplifier into the corresponding output signals for further processing.

By principle, the durable gas sensors based on the smartGAS NDIR principle are characterized by high selectivity, measurement accuracy, and long-term stability. Low detection limits, very low drift, a wide temperature range, as well as fast response time and very low maintenance and service requirements are other important advantages.