H2S detection by tunable diode laser absorption spectroscopy

Hydrogen Sulfide is a highly toxic and flammable gas. It is generated as a common by-product of many industrial processes. Early detection of H₂S at concentrations of 10 ppm in air is essential to prevent its toxic influence at higher concentrations. Tunable diode Laser based gas detectors are now being used in a wide variety of applications for safety and environmental interest. Their characteristics like non-intrusive, high selectivity, high sensitivity, and fast response time make them more appealing than conventional point sensors for a reliable H₂S detection. A long open-path H₂S sensor based on tunable diode laser absorption spectroscopy has been developed, using telecommunication near infrared distributed feed-back(DFB) tunable diode laser combining with wavelength modulation spectroscopy technology, a detection limit of 20 ppmldrm has been demonstrated, an on-board reference cell provides on-line sensor calibration. The sensor is very suitable for large area field H₂S monitoring application.