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Altech Environmental

SO2 - Sulfur Dioxide Pollutants Measured with CEMS Systems

Altech Environment offers SO2 CEMS or SO2 discrete analyzers for the continuous measurement of sulfur dioxide. Sulfur dioxide is measured using either pulsed florescence or NDIR technologies.

The pulsed florescence operating principle is based on measuring the emitted fluorescence of SO2 produced by the gas's absorption of UV radiation. Pulsating UV light is focused through a narrow band-pass filter mirror allowing only light wavelengths of 1,900 to 2,300 angstrom units (A) to pass into the fluorescent chamber. SO2 absorbs light in this region without any quenching by air or most other molecules found in polluted air. The SO2 molecules are excited by UV light and emit a characteristic decay radiation. A second filter allows only this decay radiation to contact a photomultiplier tube (PMT). Electronic signal processing transfers the light energy impinging on the PMT into a voltage which is directly analyzed. This pulsed fluorescence principle of operation was accepted by EPA under equivalency specifications defined in the February 18, 1975, Federal Register, Volume 40, No. 33 (ESQA-0486-060).

In Altech’s flagship MIR 9000, MIR-IS and MIR 9000H analyzers, non-dispersive infrared technology (NDIR) using the Gas Filter Correlation (GFC) technique is used to measure THC. The infrared bench consists of a light source, chopper, multipass sample cell, filter wheels, and solid-state detector. The filter wheel containing the optical filter and gas cells provides a dual function. One is to modulate the light; the second is to isolate the wavelengths for measurement. This configuration provides for a much simpler optical and mechanical system. The modulated light is sent into a temperature stabilized (50ºC) multipass sample cell. The MIR 9000 is available in cold/dry and hot/wet configurations.

Contact Altech for any questions you may have related to SO2 CEMS, discrete SO2 analyzers, pulsed florescence or NDIR technologies at 630.262.4400 or

Since we offer all common SO2 measurement technologies and analyzer manufactures (if you require a specific manufacturer or model), Altech tailors its system offering to your specific application.

Altech’s instruments that measure SO2 are as follows:

Emission Monitoring

Air Quality Monitoring

Engine Gas Monitoring