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The limiting oxygen concentration and flammability limits of gases and gas mixtures.

Authors
Zlochower-IA; Green-GM
Source
J Loss Prev Process Ind 2009 Jul; 22(4):499-505
NIOSHTIC No.
20035461
Abstract
This paper presents data on the limiting (minimum) oxygen concentration (LOC), in the presence of added N2, ofmethane (CH4), propane (C3H8), ethylene (C2H4), carbonmonoxide (CO), and hydrogen (H2), and some of their binary mixtures. It also addresses the issue of the flammable concentration (flammability) limits of these pure gases in air. The study is based on spark ignited explosions in large, spherical laboratory vessels (120-L and 20-L) using a 7% pressure-rise criterion for explosion propagation. The results of the study are compared with the older values which used long flammability tubes with a diameter greater than or equal to 5 cm together with visual evidence of substantial upward propagation. They are also compared to results reported recently using a 12-L spherical flask with a visual flame propagation criterion. Finally, they are compared to results reported in Europe using more modest flammability criteria and smaller chambers. The findings reported here show excellent agreement between the 120-L and 12-L results, good agreement with the 20-L results, and reasonable agreement with the earlier flammability tube values for the lower flammability limits. They disagree, however, with the more conservative European values. These results and those from the 12-L experiments also feature lower LOCs than are given by traditional flammability tubes. A model for the LOCs of such fuel mixtures based on the Le Chatelier mixture rule for lower flammable limits is seen to reasonably fit the observed results on binary mixtures and can accommodate more complex mixtures as well. One such set of ternary mixtures containing CH4 and 1:1 CO:H2 is well fitted by the model.
Keywords
Air-flow; Analytical-processes; Biochemistry; Explosions; Explosive-gases; Explosives; Flammable-gases; Fuels; Laboratory-techniques; Laboratory-testing; Mathematical-models Statistical-analysis; Author Keywords: LFL; UFL; LOC; Flammable; Gas; Mixture
Contact
Isaac A. Zlochower, Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health, Pittsburgh, PA 15236
CODEN
JLPIE9
CAS No.
74-98-6; 630-08-0; 1333-74-0
Publication Date
20090601
Document Type
Journal Article
Email Address
iaz0@cdc.gov
Fiscal Year
2009
NTIS Accession No.
NTIS Price
Issue of Publication
4
ISSN
0950-4230
NIOSH Division
PRL
Priority Area
Mining
Source Name
Journal of Loss Prevention in the Process Industries
State
PA
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