Applied Optics Vol. 48, Issue 4, pp. 695-703 (2009)
A portable cavity ringdown spectroscopy (CRDS) apparatus was used to detect effluents from small test fires in the Fire Emulator/Detector Evaluator (FE/DE) and a small room in the Building Fire and Research Laboratory at the National Institute of Standards and Technology (NIST). The output from two lasers is combined to detect four combustion gases, CO, CO2, HCN, and C2H2, near simultaneously using CRDS. The goal of this work was to demonstrate the feasibility of using a CRDS sensor as a fire detector. Fire effluents were extracted from several test facilities and measurements of CO, CO2, HCN, and C2H2 were obtained every 25–30 s. In the FE/DE test, peak concentrations of the gases from smoldering paper were 420 parts in 106 (ppm) CO, 1600 ppm CO2, 530 parts in 109 (ppb) HCN, and 440 ppb C2H2. Peak gas concentrations from the small room were 270 ppm CO, 2100 ppm CO2, and 310 ppb C2H2.