Gas Filter Correlation (Gfx) sensing builds on the photometric analysis principles used in Servomex Infrared technologies, but is enhanced to perform where extremely accurate low level measurements are required or where background gases have the potential to interfere with the measurement.
Gfx sensing is based on the ability of gases to absorb unique light wavelengths, a property used to detect the concentration of a selected gas in a mixture. Two gas filled cuvettes are mounted on a rotating disc, which pass through a beam of light alternately. One cuvette (the measure cuvette) is filled with nitrogen (typically) while the other cuvette (the reference cuvette) is filled with a sample of the gas to be measured. Light is passed through the gas to be measured: the difference in absorbance is measured and provides a direct output of the gas concentration.
Offering real-time measurement response, Gfx measurements are unaffected by background gases, and the technique is virtually immune to obscuration of the optics. This prevents sensor drift, greatly reducing calibration frequency.