Exploring the thermal characteristics, ignitions and heat release of oils and solid items at electric cooktops

Abstract

Kitchen is the most common origin of residential fires, and usually the fire starts from a cooktop. To increase the understanding of such fires, we measured the electric power and surface temperatures of three different cooktops and four frying pans, and measured the ignition times and heat release rates (HRR) from cooking oils, butter and four different solid items (pizza box, pot holder, paper towel roll, LDPE bags). The estimated ignition probability of oils and butter was 0.44 ± 0.13, with an ignition time of 309 ± 81 s and peak HRR of 300–600 kW/m2. Solid items ignited with 0.80 ± 0.10 likelihood in 378 ± 228 s, reaching higher temperatures at ignition compared to oils. LDPE bags posed the highest risk due to their propensity to ignite, melt, and burn with peak HRR exceeding 2000 kW/m2. The ignition times were mainly controlled by the cooktop heating, while the material processes delayed the ignitions by 23%. Stove guards (EN 50615 cat. B) activated before ignition in all tests, except for the pizza box and pot holder. Ignition prevention was not tested, though. Further development of the stove guard standard is therefore necessary to effectively prevent fires originating from auxiliary materials.