Richard E. Lyon

This report is a compilation of papers presented at a special symposium on Fire Calorimetry held at NIST, Gaithersburg, MD, on July 27-28, 1995. It includes papers on the theory, instrumentation, and use of fire (or heat release) calorimetry in assessing the fire hazard of materials.

Louise C. Speitel

This report presents an extensive review of the literature on the toxic and thermal hazards relating to human survival in aircraft cabin fires. Studies by various authors of exposures to single and mixed gases on humans, primates, rats and mice are presented for different activity levels and a wide range of concentrations and temperatures. Regression equations giving the best fit were derived from these studies. The regression equation which was judged to best model the human escaping from an aircraft cabin fire was selected for each gas and utilized in the survival model. The effect of carbon dioxide increasing the uptake of other gases was included in the model.

This survival model uses incapacitation data to obtain a fractional effective dose for incapacitation (FEDI) and lethality data to obtain a fractional effective dose for lethality (FEDL). The time when either FED reaches 1 determines the exposure time available to escape from an aircraft cabin fire and to survive postexposure.

Constantine P. Sarkos

The Federal Aviation Administration (FAA) has conducted numerous full-scale fire tests for the purpose of characterizing the postcrash cabin fire environment and developing improved fire test criteria for cabin materials. The tests consistently demonstrated the importance of cabin flashover on occupant survivability. Flashover is basically a sudden, very rapid spread of fire, generating large quantities of heat, smoke and toxic gases that quickly fill the cabin. Before flashover the cabin environment is largely survivable; after flashover, occupant survival becomes highly unlikely. Thermal incapacitation is more important near the fire origin and at higher elevations; whereas, toxic gas incapacitation is predominant away from the fire origin and at lower elevations. The FAA has developed and adopted improved fire test methods for seat cushions (fire blocking layers0 and interior panels (low heat release). In both cases the fire test methods are consistent with full-scale test results and serve to improve occupant survivability by delaying the onset of flashover, which produces large quantities of toxic gases, providing substantially greater available time for occupant evacuation.

Patricia Cahill

This document describes the electrical short circuit and current overload tests that were conducted on wires used in commercial transport category aircraft. This testing was conducted to evaluate the fire potential that may result from electrical faults. Results of this testing showed that circuit breakers provide reliable over current protection and that circuit breakers may not protect wire from ticking faults but can protect wire from direct shorts. It also showed that circuit breakers may not safeguard against the ignition of flammable materials by ticking faults. Preliminary testing also indicated that direct short circuits are not likely to start a fire and that direct short circuits do not erode insulation and conductors to the same degree that ticking faults do.

Matthew B. Wolf

A mathematical model was developed that could adequately describe experimentally determined transient changes in metabolic rate (MR.), an9 core and skin temperatures of human beings exposed to water-immersion conditions (0 to 28 DC). The model as the basic 25-node description of Stolwijk and Hardy, as modified to apply to a male with medium fat content. The MR increase induced by shivering was described by 3 components sensitive to 1) time-rate of change of skin temperature, 2) the product of change of skin and head-core temperatures and 3) the product of skin temperature change and the time-rate of change of head-core temperature. The model was also able to closely predict the changes in MR and skin temperatures induced by exposure to cold air. However, the predictions of rectal temperature changes were in the opposite direction to the experimental data for this case. The model was modified to describe the effects of spraying an individual with water on their head, arms and torso to simulate the action of a cabin water spray system (CWSS) activated by a fire in an airplane. The model predicted that an individual, after being sprayed and exiting into a cold and windy environment, would encounter only a minor increase in thermal stress, compared to the dry state. We conclude that mathematical simulation is an effective method of predicting thermal behavior of humans under a variety of cold conditions.