Ionic Effects in Initiation of Ignition Surface Mediated Superbase Reactivity.
Ionic Effects in Initiation of Ignition Surface Mediated
Bannister, W. W.; Chen, C. C.; Euaphantasate, N.;
Morales, A.; Tapscott, R. E.; Vitali, J. A.
Halon Options Technical Working Conference.
Proceedings. HOTWC 2000. Sponsored by: University of
New Mexico, Fire Suppression Systems Assoc., Fire and
Safety Group, Great Lakes Chemical Corp., Halon
Alternative Research Corp., Hughes Associates, Inc.,
Kidde Fenwal, Inc., Kidde International, Modular
Protection, Inc., Next Generation Fire Suppression
Technology Program, Sandia National Laboratories, Summit
Environmental Corp., Inc. and 3M Specialty Materials.
May 2-4, 2000, Albuquerque, NM, 467-479 pp, 2000.
Sponsor:National Institute of Standards and Technology,
Available from:For more information contact: Center for Global
Environmental Technologies, New Mexico Engineering
Research Institute, University of New Mexico, 901
University Blvd., SE, Albuquerque, NM 87106-4339 USA.
Fax: 505-272-7203. WEB:
halon alternatives; ignition; oxidation; vapor phases;
ignition temperature; natural gas; hot surfaces; halons
There are two generally accepted indices regarding fuel
flammability. The more commonly used index is the flash
point of the fuel (either closed or open cup), which is
the minimum temperature for a liquid fuel to sustain
sufficient levels of vapor concentration in the air
immediately over the surface to produce ignition when an
open flame is passed directly over the surface. There is
therefore the requirement for a preexisting flame.
Autoignition temperature is the minimum temperature of a
fuel "required to cause self-sustained combustion,
independently of the heating or heated element." (Since
the term "Autoignition Temperature" does not directly
evoke the concept of surface effects, the synonymous
term "hot surface ignition temperature" [HSIT], or more
simply ignition temperature, will instead be used
throughout this paper, which will delve principally on
effects of surfaces on autoignition.) In this
determination, there is no open flame involved in the
ignition. Ignition temperatures are typically determined
by applying minute portions of the fuel onto a hot
surface and waiting for up to 10 minutes until ignition
is observed (either visually or with thermoelectric
sensors). If there is no ignition, the process is
repeated with increasing temperatures, until ignition is
finally achieved. There are a number of flame processes,
including hot-flame ignition (as indexed by autoignition
temperatures (AIT), accompanied by a "rapid,
self-sustaining...readily visible yellow or blue
flame"); cool-flame ignition ("relatively slow,
self-sustaining barely luminous...cool flames visible
only in a darkened area"), indexed by cool-flame
reaction threshold (CFT, "the lowest temperature at
which cool-flame ignitions are observed"); and pre-flame
reactions, indexed by preflame reaction threshold (RTT,
the lowest temperature at which exothermic gas-phase
reactions are observed").