Study of Technology for Detecting Pre-Ignition Conditions of ... - NIST

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1.0 Introduction
CPSC-IAG95-1145
In 1994, 3,425 deaths, 19,475 injuries, and $4.2 billion in property damage were caused
by 438,000 home fires in the United States. 1 Through. analysis .of the 1988-1992 data collected
through the National Fire Incident Reporting System, NFIRS, the National Fire Protection
Association estimated that in that period, range/oven appliance fires averaged about 20 % of all
home fires and were responsible for approximately 20 YO of the injuries, 5 % of the deaths, and
5 YO of the property 10SS associated with home fires. A majotity of these range/oven fires
involved food.z Currently, there is not an adequate understanding of the pre-ignition conditions
of food fires that might be monitored to indicate an incipient fire nor of the devices that might
be used to detect and act upon such conditions. The overall objective of this project is to identify
pre-ignition conditions and the methods, materials, and devices that can be used to detect such
conditions and alert, or intervene, to reduce the risk of cooking-related fires associated with
electric and gas range:} and cooktops.
This objective was addressed through two major activities in Phase I. In order to identify
the pre-ignition conditions, experiments were performed to monitor specific aspects of the
environment and how they changed as ignition conditions were approached during heating of
various foods using combinations of range types and range-hood status (active/inactive).
Temperatures of the surroundings close to the pan as well as plume velocity and laser-attenuation
measurements were recorded. A Fourier transform infrared, FT~ spectrometer was used to
determine if the prochxtion of any specific gas species was significant. Analysis of the
experimental results his determined the conditions with potential, alone or in combination with
one another, to provide input to a pre-ignition sensor.
The second activity was the identification of methods, materials, and devices with
potential as means of detection and reaction to pre-ignition conditions. This was begun with a
literature and patent search. The search focused on sensing devices and technologies capable of
detecting one or more cooking-related conditions as well as control technologies capable of
shutting off gas and electric ranges in the event of a detected threat. The bibliographical
information on technologies related to these goals is provided with comments regarding their
potential usefulness in a range pre-ignition detection system.
2.0 Experimental
2.1 General Design
The focus of this set of experiments was to characterize the environment immediately
preceding ignition. Combinations of food type and cooking pan were chosen primarily to
investigate cases in which the food can ignite after a relatively short time of heating and likely
result in a serious fire hazard. High heating levels were chosen in order to ensure ignition, which
at low or medium settings might not occur at all or might require hours.
Three variables were changed in order to establish their effects on the pre-ignition
environment: (1) fwd type, (2) range style, and (3) hood operation. Different fbods were studied
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