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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 and Toxicity From Flexible Polyurethane Foam With and Without Copper Compounds.


pdf icon 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 and Toxicity From Flexible Polyurethane Foam With and Without Copper Compounds. (4129 K)
Levin, B. C.; Braun, E.; Paabo, M.; Harris, R. H., Jr.; Navarro, M.

NISTIR 4989; 114 p. December 1992.

Sponsor:

International Copper Assoc., Ltd., New York
Society of the Plastics Industry, Inc., New York

Available from:

National Technical Information Service
Order number: PB93-139103

Keywords:

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

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 indicating that the copper even at this low concentration was still active in reducing HCN generation. Some preliminary experiments comparing a melamine-treated and standard FPU foam (both without Cu2O) in the two phase cup furnace smoke toxicity method showed 10 times more HCN generated by the melamine-treated FPU than the standard FPU and a 90% reduction of HCN from the melamine-treated FPU when it was treated with Cu2O.