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Reduction of Hydrogen Cyanide Concentrations and Acute Inhalation Toxicity From Flexible Polyurethane Foam Combustion Products by the Addition of Copper Compounds. Part 4. Effects of Combustion Conditions and Scaling on the Generation of Hydrogen cyanide

Published

Author(s)

Barbara C. Levin, E Braun, M Paabo, Richard H. Harris Jr., Magdalena Navarro

Abstract

Two full-scale protocols (A & B) were tested to determine the efficacy of cuprous oxide (Cu2O) in reducing the concentrations of hydrogen cyanide (HCN) from flexible polyurethane foams (FPU) when thermally decomposed under "realistic" room conditions. In each Protocol A test, a FPU cushion (untreated or treated with 0.1% Cu2O) was cut in half, and the two halves were stacked on a load cell in a closed room. The ignition source was a hot wire placed between the two halves. Rats were exposed to the decomposition products to examine the toxicological effects of the foams with and without Cu2O. Protocol B differed from Protocol A in that chairs were simulated by four FPU cushions attached to a steel frame; the treated FPU contained 1.0% Cu2O; the cushions were covered with a cotton fabric; the chairs were ignited with cigarettes; and the burn room was open and connected to a corridor. In both protocols, the thermal decomposition progressed through nonflaming, smoldering and flaming phases and the concentrations of HCN and other gases were monitored. Foams used in the full-scale room burns were also examined under small-scale conditions (under flaming or a two-phase nonflaming/ramped heating mode) in the cup furnace smoke toxicity method. Both atmospheric and reduced O2 conditions were studied. The small-scale tests showed an 87% reduction in the concentration of HCN and a 40 to 73% reduction in the toxicity of the thermal decomposition products when the Cu2O-treated foams were tested. In the full-scale tests, the concentraton of HCN was reduced 70% when the FPU contained 1.0% Cu2O, but not when the foams contained 0.1% Cu2O. Investigation into this discrepancy indicated that exposing the charred residues from the full-scale burn room tests to the ramped heating mode in the cup furnace smoke toxicity method would produce significant amounts of HCN (65-90 ppm) from the untreated foam chars and only 1-2 ppm from the 0.1% Cu2O-treated foam chars
Citation
NIST Interagency/Internal Report (NISTIR) - 4989
Report Number
4989

Keywords

hydrogen cyanide, acute toxicity, combustion products, copper, polyurethane foams, melamine, thermal decomposition, inhalation toxicity

Citation

Levin, B. , Braun, E. , Paabo, M. , Harris, R. and Navarro, M. (1992), Reduction of Hydrogen Cyanide Concentrations and Acute Inhalation Toxicity From Flexible Polyurethane Foam Combustion Products by the Addition of Copper Compounds. Part 4. Effects of Combustion Conditions and Scaling on the Generation of Hydrogen cyanide , NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.IR.4989 (Accessed April 19, 2024)
Created December 1, 1992, Updated November 10, 2018