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

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CPSC-IAG95-1145
amount of room-temperature com oil was measured and poured into the pan. A stopwatch was
started as the burner was turned on at the highest setting. The temperature of the com oil was
recorded every 30 or 60 seconds. Upon ignitio~ a lid was placed on the pan to snuff out the
fire, and a C02 extinguisher was also available to assist with extinguishment.
Table 1 summarizes the conditions and results of the parametric tests, each of which was
performed once. The test plan evolved as greater understanding of the parameter interactions was
gained. The first five tests were performed on the inexpensive gas range with oil. The amount
of oil and pan type were varied. Oil cooked in stainless steel ignited in each case with the
greater amount of oil requiring more time. The combination of the average power output of the
range and the heat transfer characteristics of the aluminum pans did not enable the oil to reach
ignition temperatures. To aid in the selection of a carbohydrate test food, a sixth test was
performed on the open-coil element electric range with baked beans. Temperatures inside the pan
reached over 530 ‘C, but ignition did not occur. A seventh test was performed on the same
electric range with corn oil in a non-stick aluminum frying pan. This test was primarily used to
determine whether a fke could occur when the food was contained in an aluminum pan. The
temperature was not measured, but the oil did eventually ignite.
The results from these experiments were helpfil in deciding what materials to use in the
instrumented tests. Ah.uninum was ruled out as a pan material because of the inability of the
typical gas range to ignite com oil. Stainless steel provided both ignition and short test duration
which was desirable. The difference in oil volume for the tests conducted with stainless steel
affected the time of ignition, but did not greatly affect the ignition temperature. Similarly, the
temperature histories fix the tests using two types of aluminum pans and two amounts of oil were
different, but the final steady temperatures were comparable. Since the impact on test duration
was not large and find temperatures were similar, pan sizes and fmd amounts were selected
using reasonable cooking practices. The lack of ignition of the baked beans, although they were
heated in an aluminum pan, discouraged the use of this food in the fully-instrumented tests since
the ability to ignite ww doubtfid.
2.1.4 Instrumented-Test Parameters
Table 2 summarizes the food types, amounts, and the pans selected for testing. The
rationale behind the selection of vegetable oil was that preheating oil in a pan before Cooking a
solid food item inside is a common practice and is a known circumstance leading to many
cooking fires. Also, oils vaporize more readily than solid finds and thus cause more intense
fires. Soybean oil wa$ the particular oil chosen because it holds 75 YO to 80 % of the cooking
oil market.3 Most commonly used vegetable oils are processed in order to have less than 2 YO
free fatty acid content. This translates into similar smoke (140 ‘C -230 “C), flash (275 ‘C -
335 “C), and fire (350 ‘C -365 “C) points. 4 The pan size was selected so that the 20 cm (8 in)
burner &ea would most closely match the area of the bottom of the pan. The volume of oil was
chosen to provide a reasonable depth for f~ing in the pan.
Bacon was chosen as the second food. The rationale behind the selection of bacon was
that animal fats and greases are other commonly cooked foods, and grease and oil fires seem to
be the most prevalent cooking fires. Another scenario that was considered was the frying of lard
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