Induction periods before ignition

It is not possible to propose a general mechanism from these studies, for results do not correspond to a definite pattern. Although, in all the systems, secondary amines are the most effective inhibitors, the role played by tertiary amines is confusing. In several systems (Table I, No. 1, 2, and 3) tertiary amines are much more effective than primary amines, but in others they appear to have little or no effect. Again, in acetaldehyde oxidation (Table I, No. 1 and 2) there is generally a linear relationship between the amount of inhibitor added and the induction period before either slow oxidation or ignition of the fuel occurs. In other systems (Table I, No. 3, 4, and 5), however, a much more complex relationship is obtained. Thus, amines may be acting by different mechanisms in different systems. 

The dialkylzincs up to the dibutyl derivatives readily ignite and bum in air. The higher alkyls fume but do not always ignite [1]. During preparation of dialkylzincs, reaction of the copper—zinc alloy with mixed alkyl bromides and iodides must begin (exotherm, often after a long induction period), before too much halide mixture is added, or violent explosions may occur [2]. Reactions with water may be explosive [3]. 

The disappearance of nitrogen dioxide during the induction periods before slow reaction or ignition in mixtures of H2,02, and NO2 has been followed photometrically. The lengths of the induction periods are discussed in relation to the rate of the reaction NO2 + H2 — NO + H2O. Conditions for ignition are briefly indicated. 

Thermal Explosions - Part I. Induction Periods and Temperature Changes before Spontaneous Ignition , TrFaradSoc 55(4), 581-90(1959) 34e) G.M. Muller D. 

In the 2nd series of tests, the cold container with sample was suddenly plunged into a bath maintained at constant temp which was close to or slightly above t° Q, and the time interval before the ignition takes place (known as delay to ignition or induction period) was measured and the temp exprapolated to 5 sec period. Detailed description of procedures is given in Ref, pp 206-07... 

As the graph in Fig. 72 shows after the temperature of surrounding bodies or noedium tb is established in the fuel mixture and before temperature of self-ignition tj is attained at poinf B, some time still passes before the fuel mixture self-ignites. This time lapse is referred to as the induction period or the time lag. 

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