Autoignition temperature
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Autoignition_temperature".

The autoignition temperature or kindling point of a substance is the lowest temperature at which it will spontaneously ignite in a normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion. The temperature at which a chemical will ignite decreases as the pressure increases or oxygen concentration increases. It is usually applied to a combustible fuel mixture.

Autoignition temperatures of liquid chemicals are typically measured using a 500 mL flask placed in a temperature controlled oven in accordance with the procedure described in ASTM E659 1.

content

Contents

Autoignition equation

The time t_{ig}\, it takes for a material to reach its autoignition temperature T_{ig}\, when exposed to a heat flux q''\, is given by the following equation

t_{ig} = \left ( \frac{\pi}{4} \right ) \left (k \rho c \right )\left [ \frac{T_{ig}-T_\infty}{q''} \right] 2

where k = thermal conductivity (W/(m·K)), ρ = density (kg/m³), and c = specific heat capacity (J/(kg·K)) of the material of interest. T_\infty is the temperature, in kelvins, the material starts at (or the temperature of the bulk material), and q″ is the heat flux (W/m²) incident to the material.

Autoignition point of selected substances

 This section does not cite any references or sources.
Please help improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed. (August 2008)

References

  1. ^ E659 – 78 (Reapproved 2000), "Standard Test Method for Autoignition Temperature of Liquid Chemicals", ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959
  2. ^ Principles of Fire Behavior. ISBN 0-8273-7732-0. 1998.
  3. ^ "Handbook of Physical Testing of Paper, By Jens Borch, Richard E. Mark, M. Bruce Lyne". Retrieved on 2008-09-08.

See also

External links
© jGames.co.uk 2007 (some content from Wikipedia under GDL ) !-- ValueClick Media 468x60 and 728x90 Banner CODE for jgames.co.uk -->
Your Ad Here