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

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which is sometimes preheated for the intiodutiion of a vegetable, but cook~ng a meat which
creates its own grease is more common. Like vegetable oils, greases vaporize easily and may
cause intense fires. The mass was chosen as a raonable mount to be-cooked in a 26 cm (10.3
in) pan. This scenario would be especially appropriate for a cook who was in a bun-y and
therefore heated EN the bacon at once on a high heat setting.
Table sugar was chosen as the third food as an example of a carbohydrate. Sugar contains
almost no water or ask and its low melting point allows faster vaporization than unprocessed
vegetable matter. The rationale behind this selection included verbal evidence from several
people who had expetiencd prob~ems with sugar ignition. The preliminary experiment with
baked beans and other tests pefiomed at CPSC labs with pasta and potatoes all indicated
difilcul~ or unlikelihood of igniting more wmmonly cooked cmbohydrates.
The testing schedule was developed to stiemline the test set-up and to lessen the
possibility of systematic errors (thou@ randomness) surfacing in the results. The test matrix is
presented in Table 3. A total of men~-~o tests were conducted, of which only two used the
smoothtop range. Six of the tests were repeated to detemine consistency of results. The
selection of tests to be repeated was random because all of the tests exhibited similar smoking
and ignition phenomena. A general overview of the ignition behavior of the various scenarios
was desired which would lead to more rigorous testing of a specific signature or signatures in
Phase II under a variety of conditions to determine widespread applicability and reliability.
2.2 I~sme~tatio~
A variety of instruments was implemented to attempt to characterize the pre-i~ition
cooking environment. Memuremen= focused on themal aspects of the area with an attempt to
gain chemical, plume smoke, and plume velocity information as well. The goal of the effort was
to ascertain which mewuremen@ are effective for indicating approaching ignition conditions
without regard to practicality which will be a subject of fvture studies. Figure 2 is a pictorial
diagram of the layout of the instmmen~ for these tests.
2.2.1 Thermocouples
Thermocouples were used to measure temperatures in three general areas: the plume, the
p- and the range. The buoymt plume above the pan which consisted of hot air, gases, and food
aerosols generated by the heating process was equipped with a grid of thermocouples as shown
in Figure 3. The vertical centerline, or axis of symmetry, of the pan was monitored with six
thermocouples, and three heights were h~rizontally mapped with three additional thermocouples
each. The themomuples were Omega model no. 5TC-GG-(K)-30-(72) [30 gauge, 0.25 mm
(0.010 in) diameter, K-type (Chromel-Alumel), 183 cm (72 in) long, glass braid insulation].
*Certain commercial equipment, instruments, or materials are identified in this report to
specify adequately the expetimentil procdure. Such identification does not imply
recommendation or endorsement by the National Institute of Standards and Technology, nor does
it imply that the materials or equipment identified are necessarily the best available for the
purpose.
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