Date of Award

January 2014

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department

Safety, Security, and Emergency Management

First Advisor

Gregory E. Gorbett

Department Affiliation

Safety, Security, and Emergency Management

Second Advisor

Andrew T. Tinsley

Department Affiliation

Safety, Security, and Emergency Management

Third Advisor

E. Scott Dunlap

Department Affiliation

Safety, Security, and Emergency Management

Abstract

A study was conducted to evaluate the competency of several types of electric cooktop ranges igniting a variety of common kitchen items. Four types of electric cooktop ranges were tested including a ceramic-glass cooktop range, an electric coil cooktop range, an electric coil cooktop range with cast iron plate installed, and an electric coil cooktop range with a temperature-limiting control sensor. The latest research was reviewed to select a representative sample of fuels commonly noted as the first fuel ignited in kitchen fires. The nine selected fuels included cardboard (pizza box), a cotton dish towel, a roll of paper towels, a pan of canola oil, a pan of vegetable oil, a nylon short turn spatula (cooking utensil), a kitchen appliance (toaster), a plastic storage container, and a pan of corn oil.

Each range was tested in the high, medium, and low thermostat settings on the large (8" diameter) and the small (6" diameter) heating elements resulting in a total of 54 tests per range type. An additional eight tests were completed to insure repeatability of results. As confirmations of repeatability, the high thermostat setting for each heating element diameter was tested again on each cooktop range. Cardboard was selected as the fuel for the repeatability tests. A variety of data was collected for each test including video photography, infrared video photography, still photography, and thermocouple data. The heat sources were characterized using both thin skin calorimeters and heat flux transducers (radiometers).

The high thermostat setting for all three cooktop types, excluding the temperature-limiting sensor cooktops, tested at both the 6-inch and 8-inch diameter heating element resulted in the ignition of 47 of 54 tests. The temperature-limiting sensor cooktop did not ignite any of the fuels on any setting. Table 43 quickly illustrates, as logic would, that the potential for ignition is greatest when the cooktop is set to the high thermostat setting. The ceramic glass cooktop resulted in a 72% ignition on the high setting while both the electric coil cooktop and cast iron plate cooktop resulted in a 94% ignition on the high setting. Although not all fuels ignited at the high thermostat setting, it was noted that the potential for ignition was possible due to the quick consumption of mass, smoldering combustion (cellulosic fuels), and increased volume of vaporization/pyrolysis products. The high setting for all three cooktop types showed the maximum potential for ignition based on the total heat output produced by the 6-inch diameter and 8-inch diameter heating elements. No fuels ignited at the high setting for the temperature-limiting sensor cooktop.

The medium setting for all three cooktop types for both diameter heating elements resulted in few instances of flaming combustion of the fuels. Approximately half of the fuels tested on the ceramic-glass cooktop ignited at the medium setting, while it was more difficult to ignite fuels on the electric coil and cast iron plate cooktops. Although only select fuels ignited on the different electric range types tested at the medium-setting, it was noted that a majority of the fuels did demonstrate the potential of reaching flaming combustion through evidence of smoldering combustion and significant loss of mass for those cooktops without the temperature-limiting sensor. The medium setting for all three ranges demonstrated moderate potential for ignition based on the total heat output produced by the 6-inch diameter and 8 inch diameter heating elements. No fuels ignited at the medium setting for the temperature-limiting sensor cooktop.

The low setting for all four cooktop types tested for both the 6-inch and the 8-inch diameter heating element resulted in no flaming ignition. All tests conducted using the three different electric range types for both the 6-inch and 8-inch diameter heating elements demonstrated no potential for ignition of any of the fuels tested. Based on the research conducted it can be concluded that the low setting for all three electric range types has minor-to-no potential for ignition of the fuels tested. This study has validated a number of configurations of electric cooktop ranges in a variety of ignition scenarios. The competency of aforementioned cooktops as an ignition source given a number of common household fuels has been reported on in extensive detail within the body of this report.

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