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Probability of Resistive Spark Ignition Caused by Very Low Currents.

Authors
Cawley-JC
Source
MISSING :11 pages
Link
NIOSHTIC No.
10005805
Abstract
The Bureau of Mines has empirically determined ignition probability versus current for resistive circuits in an 8.3% Methane-air atmosphere. Simple ignition probability, defined as the number of ignitions divided by the total number of sparks, was determined, and the corresponding currents were recorded. The experiment was designed to minimize the probability of not observing an ignition that should occur during a series of tests. For resistive circuits in 8.3% Methane-air mixtures, the experimental results indicate that ignition was not achieved below 2,000 ma at 20 V DC, 350 ma at 30 v DC, 150 ma at 40 V DC, and 175 ma at 50 V DC. The simple probability of ignition corresponding to these currents is estimated to be, respectively, 1.0 X 10-6, 1.7 X 10-7, 3.0 X 10-7, and 1.0 X 10-5. The ignition mechanism seems to break down below this point, implying that a threshold current value exists below which spark ignition does not occur.
Publication Date
19870101
Document Type
IH; Report of Investigations;
Fiscal Year
1987
NTIS Accession No.
NTIS Price
Identifying No.
RI 9114
NIOSH Division
PRC;
Source Name
MISSING
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