SYMPOSIA PAPER Published: 01 January 1987

Ignition Probability of Hybrid Mixtures


The behavior of hybrid mixtures (combustible dusts and flammable gas in air) has been studied at concentrations near to the lower limit. The mixtures were comprised of polyethylene particles (5 to 50 μm and 30 to 44 μm) and either ethylene or methane. Experiments were undertaken in a modified Hartmann vertical tube apparatus with a resistive/capacitive spark discharge circuit. The measured variables in the system were: dust concentration, addition of flammable gas, total ignition energy, and rate of its delivery to the spark channel. Thereby, minimum ignition energies (MIE) given in terms of series resistances and lower flammable limits (LFL) were obtained. The results obtained were compared with values in the literature. This led to consideration and reporting of the significance and confidence of experimentally determined values of MIE and LFL. Extensive measurements on the ignition of hybrid mixtures demonstrated that simple additivity does not apply. Probability of ignition was increased by addition of flammable gases, the type of which proved to be of major importance.

Author Information

Napier, DH
University of Toronto, Toronto, Ontario, Canada
Roopchand, DR
University of Toronto, Toronto, Ontario, Canada
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Developed by Committee: E27
Pages: 310–323
DOI: 10.1520/STP28182S
ISBN-EB: 978-0-8031-5019-5
ISBN-13: 978-0-8031-0957-5