Smoke Gas Analysis by FTIR Method. Preliminary Investigation

The FTIR spectrometer equipped with a long path gas cell was used in on-line gas analysis in connection with the Cone Calorimeter. It pro vided a sensitive and effective gas analyzer for the seven gases (CO, CO ₂ , HCN, HC1, SO ₂ , NO ₂ and acrolein) measured. Test materials (PUR, PVC and wool carpet) produced at 50 kW/m ² irradiance measurable concentrations of all the other gases except NO ₂ and acrolein in spite of effective dilution of smoke gases by high air flow in the Cone Calorimeter. Concentrations of the gases evolved in the Cone Calorimeter could be measured frequently enough even from mate rials, which have short burning times. After careful calibration the precision of FTIR analysis can be the same as in commercial on-line gas analyzers. Actual precision of on-line specific gas analyzers may be even worse than that of FTIR because of overlapping impurities. The heatable sample line and gas cell en sures that components of the fire gas mixture do not condense on the walls on the way to the instrument. Because FTIR technique has capacity for on-line analysis and simultaneous measurement of several gases, it is a suitable analy sis method to be used in connection with the Cone Calorimeter and with other fire tests. The sensitivity of FTIR method is adequate for toxicity evaluations. The analysis results can be used as data in mathematical models to predict toxic eflects in fires.