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auto ignition temperature

auto ignition temperature

auto ignition temperature

Is there any relation between auto ignition temperature and C-H ratio?

Many thanks

RE: auto ignition temperature

In a homologous series of organic compounds, the Auto ignition temperature (AIT) decreases with increasing molecular weight. Also a branched compound will have a higher AIT than the corresponding straight-chain compound. There is a plot for straight chain paraffins in one of the NFPA publications. The subject is discussed in Bodurtha's book on Industrial Explosion Prevention and Protection.

HAZOP at www.curryhydrocarbons.ca

RE: auto ignition temperature

The only probable exception to owg's statement is acetylene.

From the net:

AIT = Minimum Autoignition Temperature in oC under test conditions.

        n-butane                              370
        n-pentane                            260
        n-hexane                             225
        n-heptane                            225
        n-octane                              220
        n-decane                              210
        n-dodecane                           204
        n-tetradecane                       200

        2-methylpropane                    460
        2-methylbutane                      420
        2-methylpentane                    306
        2,2,3-trimethylbutane              420
        2,2,4-trimethylpentane            415

        cyclopentane                          380
        cyclohexane                            245
        methylcyclohexane                 250

        benzene                                560
        toluene                                 480
        ethyl benzene                        430
        meta-xylene                          463
        para-xylene                           530
        ortho-xylene                          530

RE: auto ignition temperature

Ethylene and acetylene auto ignition temperature needs clarification.  These two chemicals decompose into C +CH4 + H2, raising the pressure by a factor of three and giving off large amounts of energy.  Their auto decomposition temperature is a function of pressure.  Quite a tricky pair.

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