Self-sustaining combustion

The autoignition temperature is the minimum temperature required for self-sustained combustion in the absence of an external ignition source. The value depends on specified test conditions. Tht flammable (explosive) limits specify the range of concentration of the vapor in air (in percent by volume) for which a flame can propagate. Below the lower flammable limit, the gas mixture is too lean to burn above the flammable limit, the mixture is too rich. Additional compounds can be found in National Fire Protection Association, National Fire Protection Handbook, 14th ed., 1991. 

The ignition temperature or autoignition temperature is the minimum temperature of a flammable mixture that is required to initiate or cause self-sustained combustion without ignition from an external source of energy such as a spark or flame (ASTM D2155). 

The ignition temperature is the minimum temperature required to initiate or cause self-sustained combustion. Table 2 also Hsts ignition temperatures of several common ethers. Attention is directed to the particularly low ignition temperature of ethyl ether, especially with reference to some common ignition sources such as a lighted cigarette (732°C) or a pressurized (0.7 MPa or 100 psi) steam line (180°C). 

Auloignition lempemlure The lowest temperature of a material required to initiate or cause self-sustained combustion in the absence of a spark or flame. This temperature can vary, depending on the substance, its size, and the shape of the igniting surface or container and other factors [32]. 

AUTO-iGNiTiON TEMPERATURE The minimum temperature required to initiate or cause self-sustained combustion of material in the absence of any external source of energy. (Values may change significantly with geometry, gas/vapour concentration, and if catalyst is present.)... 

Substances applied to or incorporated in a combustible material (e.g. organic polymers, nylon, vinyl and rubber, etc.) to reduce flammability. Act by retarding ignition, control/douse burning, reduce smoke evolution. Slow down or interrupt the self-sustained combustion cycle when the heat-flux is limited. Flame retardants (FRs) improve the combustion behaviour and alter the combustion process (cool, shield, dilute, react) so that decomposition products will differ from nonflame retarded articles. FRs are usually divided into three classes ... 

The autoignition temperature of a substance is the lowest temperature at which a solid, liquid, or gas will spontaneously ignite resulting in self-sustained combustion without the need for an external ignition source. A material released from a process above its autoignition temperature will ignite. Autoignition temperatures of some common materials are shown in Table B-2. 

The conditions where the temperature gradient at the surface is zero are determined by van t Hoff (VH) points, denoted by triangles in Fig. 26.1. If surface radiation is neglected, VH points correspond to adiabatic operation, i.e., conditions for self-sustained combustion. For each pressure, a second VH point occurs at a higher temperature (not shown for figure clarity). 

The mere presence of the ash seems responsible for the ability of the LP3—AP propellant to undergo self-sustained combustion to pressures as low as 0.005 atm., an order of magnitude less than PBAA-AP and PB(CT)-AP propellants, and to maintain a relatively high burning rate at such low pressures. Two questions are of interest why does it form, and how does it sustain the burning rate It is not clear why the ash forms. It may be related to Bircumshaw and Newman s (14,15) discovery that only 30% of the original AP decomposes when the temperature is below ca. 350 °C. and that the remaining 70% is unreacted solid AP, and to the fact that the surface temperature and the temperature in the ash were measured by Most (60) as 250° 300°C. (The GDF theory with a collapsed A/PA flame indeed predicts a low surface temperature, ca. 400°C. below 0.01 atm.)... 

Auto-Ignition Temperature The minimum temperature to which a material must be heated to initiate self-sustained combustion, independent of any open flame. 

Autoignition Temperature—Minimum temperature of a substance to initiate self-sustained combustion independent of any ignition source [2.1]. 

ADN and compositions of ADN have been shown to be able to undergo self-sustained combustion with higher burn rates than the commonly used oxidizer AP. A basic study showed that the bum rate for compressed ADN was 7.4 mm/s at the sub-atmospheric pressure of 0.2 MPa and 54 mm/s at 6 MPa. Since ADN has a surplus of oxygen, its burn rate increases if a carbon source is added. The low-pressure burning is then expanded down to 0.02 MPa. The burn rate for a mixture of ADN and paraffin in the ratio 90 10 has been determined to be 50 mm/s at 7 MPa with a burn rate coefficient of 0.8 and a flame temperature of 2960 [17]. 

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