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Observations on the Generation of Toxic Products in the NFPA/ISO Smoke Density Chamber



Nathan D. Marsh


Efforts are underway in several research groups to adapt existing flammability test methods for the determination of yields of toxic compounds such as CO, HCN, and HCl. These include the NFPA 269 / ASTM E 1678 radiant apparatus, the ISO/TS 19700 tube furnace, the NFPA 271 / ASTM E 1354 cone calorimeter, and the NFPA 270 / ISO 5659-2 smoke density chamber. In each case a small (order cm) specimen, cut from an item of furnishing or other building content, is burned and the evolved gases measured, in order to calculate the yields of toxic gases, ideally for different fire stages such as well-ventilated flaming or post-flashover flaming. The goal of these efforts is to facilitate obtaining the yields of toxic gases from principal combustibles for use in fire safety engineering. This will enable managing the exposure of building occupants to fire effluent and, in turn, providing realistic time for their escape. In our own work, tested specimens representative of finished goods were: a particleboard with a polyvinyl chloride (PVC) veneer, a polyurethane foam with a cotton/polyester cover fabric, or PVC clad, nylon insulated 3-conductor electrical cable. Gas volume fractions were monitored by a non- dispersive infrared gas analyzer (CO, CO2), a paramagnetic gas analyzer (O2), and a Fourier transform infrared spectrometer (HCN, HCl, and other gases not detected in this study). These techniques were most recently applied to the NFPA 270 / ISO 5659-2 smoke density chamber. In addition to the monitoring of optical density, gas samples were drawn continuously from fittings located in the top center of the chamber, and after passing through the gas analyzers, were returned via another fitting nearby. Flows were maintained at a few L/min to avoid stirring of the chamber contents; however, we did observe some buoyancy-induced circulation. For the purpose of determining gas yields (in g/g of material burned) the thickness of the hot upper layer is an important factor but
Proceedings Title
Proceedings of the 2010 Interflam Conference
Conference Dates
July 5-7, 2010
Conference Location
Conference Title
Interflam 2010


product flammability, smoke, toxicity, test methods


Marsh, N. (2010), Observations on the Generation of Toxic Products in the NFPA/ISO Smoke Density Chamber, Proceedings of the 2010 Interflam Conference, Nottingham, -1, [online], (Accessed April 19, 2024)
Created July 4, 2010, Updated January 13, 2021