Arthur F. Grand

Effects of Combustion Gases on Escape Performance of the Baboon and the Rat

In postcrash aircraft fires, only a few minutes are often available for egress. To assess the potential of selected combustion gases (CO, acrolein and HCl) to impair human escape, a signalled avoidance task was developed for use with the juvenile African Savannah baboon. After a 5-minute exposure, the animal was required to select and depress the correct lever to open an escape door and then to exit into the adjacent compartment of a shuttlebox. With CO, the EC50 for escape failure was 6850 ppm. Acrolein (12 to 2780 ppm) neither prevented escape nor affected escape times, despite irritant effects at all concentrations. Similar results were obtained with HCI (190 to 17,200 ppm) in that, despite severe irritant effects, all animals successfully performed the escape task. With a comparable shuttlebox and escape paradigm for rats, the EC50 of CO was 6780 ppm. Five-minute exposures to HCI (11,800 to 76,730 ppm) did not prevent escape but severe post-exposure respiratory effects and lethality occurred at 15,000 ppm and higher. In both species, escape time was not affected by HCI but a concentration-related increase in intertrial responses was evident. The data suggest that laboratory test methods for measurement of incapacitation of rodents may be useful in evaluating potential effects of atmospheres containing CO or irritant gases on human escape capability.

Hydrogen Chloride Transport and Decay in a Large Apparatus I. Decomposition of Poly(Vinyl Chloride) Wire Insulation in a Plenum by Current Overload

Large-scale combustion product evaluation experiments were carried out in a realistic room-plenum arrangement. A 30 ft. (9.14 m) length of electrical power wire with flexible PVC jacket and insulation was decomposed, in a plenum, by the action of an electrical overload. The combustion gases measured were HCl, CO, CO 2 and unburned hydrocarbons. The maximum con centration of HCl in the plenum was 3000 ppm (which represents roughly one third of the total chlorine in the wire). However, this amount decreased rapidly so that only 200—300 ppm remained at the end of 30 min; none of the other combustion gases measured decayed significantly. Little or no HCl was found in the living space, except in one experiment with forced air recirculation, when a maximum concentration of 200 ppm was measured. Reasonable ac counting is presented for the very large proportion of HCl missing from the at mosphere.

Modeling of Toxicological Effects of Fire Gases: Iii. Quantification of Post-Exposure Lethality of Rats From Exposure To HCl Atmospheres

This paper, the third in a series of publications on the modeling of tox icological effects of fire gases, addresses the quantification of post-exposure lethality of rats from exposure to hydrogen chloride atmospheres. Experimental L(Ct)50 values for HCl varied from about 80,000 ppm-min (5-minute exposure to 16,000 ppm) to about 170,000 ppm-min (60-minute exposure to 2800 ppm). Rele vant data involving non-human primate exposures are cited, which suggest the comparability of the rat and the primate for the purpose of assessing lethal doses of HCl.

Modeling of Toxicological Effects of Fire Gases: VI. Further Studies on the Toxicity of Smoke Containing Hydrogen Chloride

Studies of rodent lethality due to exposure to HCl, as well as to mixtures of HCl and CO, have shown different apparent toxicological effects at low and at high concentrations of HCl. At low concentrations of HCl, sensory irritation causes a decrease in respiratory minute volume, with somewhat slower loading of CO and a delay in incapacitation. This effect is observable only at low con centrations of CO. At much higher HCl concentrations, pulmonary irritant ef fects are observed leading to postexposure lethality. An empirical analysis of the data for mixtures of HCl and CO suggests that exposure doses leading to lethality may be additive. The lethal toxic potency (LC50) of PVC smoke may be largely, but not entirely, accounted for by the HCl produced. However, PVC smoke exhibits a greater in cidence of early postexposure deaths. The early deaths, which may be partially attributable to a combined effect of CO and HCl, may also be linked to the pattern of respiratory penetration by the smoke. There is evidence that com ponents other than HCl are present which cause PVC smoke to be more irri tating than HCl alone.

Acute Inhalation Toxicity of the Smoke Produced By Five Halogenated Polymers

The acute inhalation toxicity of smoke produced by five halogenated polymers used as electrical wire coatings was investigated in this study. The polymers in cluded two chlorofluoropolymers (Halar 500® and Halar 555®) and three fluoro polymers (Teflon 100® , Tefzel 200® and Kynar® ). The toxicity of each material was evaluated under flaming and nonflaming combustion using the NBS developmental protocol supplemented with measurement of incapacitation and analyses of the combustion atmospheres for HF, HCl and COF2.

Toxicity and the smoke problem

Abstract The production and toxicological effects of selected, major fire gases are reviewed. These gases include carbon monoxide, hydrogen cyanide, carbon dioxide, irritants and oxygen depletion, among others. The measurement of the toxicity of smoke is discussed relative to the parameters which need to be measured, in addition to some selected, existing test methods. These test methods are reviewed relative to their relevance to “real” fires, utility and appropriateness as standard tests.

Modeling of Toxicological Effects of Fire Gases: VII. Studies on Evaluation of Animal Models in Combustion Toxicology

This study evaluated the potential use of the guinea pig as an animal model in conducting combustion toxicology experiments in which lethality is the end point. The guinea pig was found to be approximately three times as sensitive as the rat upon exposure to hydrogen chloride, presumably due to its tendency for bronchoconstriction. Compared to the rat, the guinea pig was relatively in sensitive to carbon monoxide. Lethal effects of mixtures of carbon monoxide and hydrogen chloride showed additivity only at relatively high concentrations of carbon monoxide. The lethal toxic potency of hydrogen cyanide was about the same for both the rat and the guinea pig. Based on comparisons of available toxicity data for humans and nonhuman primates, it was concluded that the rat is the better model when lethality studies are used. However, it is uncertain which animal model would be better when sublethal exposures, particularly to irritants, are considered.

Evaluation of the Corrosivity of Smoke from Fire Retarded Products

A laboratory radiant combustion/exposure apparatus was used to evaluate the corrosion of copper test probes due to smoke from burning polymers. This apparatus is under consideration by an ASTM task group for development of a standard test procedure for corrosive properties of smoke. The brief test series was conducted with several different fire-retarded polymers and non-fire retarded polymers, and comprised the use of two different heat flux fire exposures and the option of adding moisture to the atmosphere. Recommen dations are presented for further test programs to improve upon the proposed standard test methodology.

Flammability studies of thermally resistant polymers using cone calorimetry

The effectiveness of a set of thermally resistant polymers was evaluated for aircraft applications using the cone calorimeter (ASTM E1354/ISO 5660) under heat fluxes simulating real scale fires. This study included eight developmental and commercial thermally resistant polymers available in the literature and/or marketplace. The polymers included were aromatic polyester, polyetherimide, fluorine-containing polyetherketone, phosphorus and fluorine-containing co-polyetherketone, fluorine and phosphorus-containing polyether, fluorine-containing polyester, poly(dimethylsiloxane)etherimide and polysulfone. The effects of fluorine, phosphorus, silicon and sulfone group in polymers were examined. This evaluation was based on time to ignition, peak, average and total heat release rates obtained at an external heat flux of 50 kW/m2. Other parameters such as effective heat of combustion, mass loss and rate of smoke and toxic gas evolution were collected during the cone calorimeter test. Copyright

Continuous Monitoring of Hydrogen Chloride in Combustion Atmospheres and in Air

A continuous analyzer for hydrogen chloride gas, based on a French standard method, has been utilized for measurement of HCl in laboratory-generated combustion atmospheres and in air. The method is based on continuous titra tion of chloride with silver in aqueous solution. The process is monitored by commercially available automated titration equipment, a mass flowmeter and a dedicated Apple IIe microcomputer. Pure HCl in air was monitored in a steady-state flow-through system and compared to sampling by soda lime tubes. Hydrogen chloride in PVC smoke (both flaming and nonflaming combustion conditions) was monitored in both flow-through and static environments, in cluding an apparatus designed for steady-state combustion. The advantages, disadvantages and recommendations for further study of this technique are discussed.