Temperature of ignition

A material that is above its autoignition temperature will ignite spontaneously on contact with air in the correct proportions (see Table 6.1 for minimum temperature of ignition source). 

Figure 4. Temperature of ignition points in relation to percent hydrogen in air.

The Temperature of Ignition of Hydrogen and Oxygen.—When the two gases are mixed in the proportion of two volumes of hydrogen and one volume of oxygen it has been found that the temperature of the mixed gases must be raised to about 580° C. ... 

The temperature of ignition of a mixture fired by adiabatic compression Is lower than when the same mixture is fired by being heated in a glass or silica tube at atmospheric pressure. Professor H B. Dixon in a private communication to the author states that he found the ignition temperature of electrolytic gas under the latter conditions to be 580° C. 

Phosphine is an offensive smelling, poisonous gas which in the pure state is not spontaneously inflammable However, its temperature of ignition is very low thus, if a stream of phosphine is allowed to impinge in air on a glass vessel containing boiling water, it will immediately burst into flame, burning with considerable luminosity, in accordance with the equation —... 

Dust in Air of Temperature of Ignition, °C Lower Limit in g/m of Mixture... 

Ignition Time and Temperature of Ignition Relationship. See Vol 1, p XVII... 

Thermal sensitivity Temperature of ignition of FOX-7 is 215 °C as against 220 °C for RDX (Wood s metal bath). Further, excellent thermal stability is indicated by vacuum stability test for both FOX-7 as well as RDX. 

The temperature of the propellent gases depends on the heat of explosion and on the gas composition. The greater the heat of explosion, and hence the temperature of gases, the more readily the secondary flame arises. Powders of a low calorific value may therefore give, no secondary flame if the temperature of the gas mixture is lower than the temperature of ignition. 

Explosive substance Temperature of ignition via hotspots/ °C Temperature of thermal ignition/ °C... 

Taffanel s indisputable achievement is his statement of the problem of flame velocity in a mixture characterized by a specific smooth dependence of the reaction rate on the temperature, whereas many authors, both before and after Taffanel, based their calculations on the concept of an ignition temperature at which there was supposedly a jump in the reaction rate. This achievement is a consequence of the theory of self-ignition which Taffanel developed in which the temperature of ignition depends on the interrelation between the continuously varying heat release rate and the conditions of heat transfer. 

The value for y was taken as 1-40, and the assumption made that there was no loss of heat during the compression of the gases in the cylinder. Actually that was not quite the case, but experiment showed that the compression lasted only about 0-06 second m the case of electrolytic gas, so that the loss of heat would be small. The effect would be to raise the calculated temperature of ignition. The experiments were carried out by the method of trial and error, by regulating the number of steel collars until an explosion just took place. The initial and final volumes were thus known, and these data, coupled with the initial temperature, enabled the ignition temperature to be calculated from the equation given above. The main results obtained are given in the table on p. 112. 

---