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Study of Technology for Detecting Pre-Ignition Conditions of Cooking-Related Fires Associated With Electric and Gas Ranges and Cooktops. Phase 1 Report.


pdf icon Study of Technology for Detecting Pre-Ignition Conditions of Cooking-Related Fires Associated With Electric and Gas Ranges and Cooktops. Phase 1 Report. (7589 K)
Johnsson, E. L.

NISTIR 5729; 115 p. October 1995.

Sponsor:

Consumer Product Safety Commission, Washington, DC

Available from:

National Technical Information Service
Order number: PB96-128095

Keywords:

stoves; appliances; fire detection; fire prevention; ignition prevention; kitchen fires; residential buildings; sensors; smoke detectors; smoke measurement

Abstract:

A significant portion of residential fires stem from kitchen cooking fires. Existing fire data indicate that cooking fires primarily are unattended and most often involve oil or grease. The purpose of this investigation was to ascertain the existence of one or more common features or characteristics of the pre-ignition environment that could be used as input to a sensor in a pre-fire detection device. The ultimate goal of this continuing study is to evaluate the feasibility of incorporating such a device into the range that would react to a pre-fire condition and reduce the occurrence of unwanted kitchen fires. The focus of the study was unattended foods placed in pans on burners set to high heat. Experiments were conducted with three different foods and with gas and electric ranges to investigate the pre-ignition environment of actual range-top cooking fires. Numerous temperatures in the near surroundings as well as local plume velocity and laser-attenuation measurements were recorded. A Fourier transform infrared spectrometer was used to observe significant species production above the food. Results of these experiments are presented and evaluated. The second part of this study was a literature and patent search of technologies with the capability to act as either the sensor in a pre-fire detection device or as the automatic control that would respond to a detector warning signal by shutting off the gas or electricity supply. A broad range of potential detection technologies was reviewed because the pre-fire signatures had not yet been identified. A bibliography and comments on the applicability of different technologies are included. The conclusions pertaining to the experiments are based on measurements and observations of combinations of specific ranges, pans, foods, and ventilation so extrapolation to other conditions should be performed with caution. The major conclusions of this research are as follows: (1) Strong indicators of impending ignition were temperatures, smoke particulates, and hydrocarbon gases. (2) Promising detection technologies include: tin oxide (SnO2) sensors for hydrocarbon detection, narrow band infrared absorption for hydrocarbon detection, scattering or attenuation types of photoelectric devices for smoke particle detection, thermocouples for thermometry of the burner, pan, range surface (top and below), or range hood. (3) Logical processing of signals from two or more of the detection technologies could be an important means by which false alarms of pre-ignition conditions are elimianted. (4) Control technologies exist that are applicable to the safe shutdown and restart of gas and electric ranges upon detection of approaching ignition.