Dependence of the lower flammability limit on the initial temperature

The dependence of the lower flammability limit on the initial temperature is studied experimentally and numerically for upward flame propagation at a pressure of 0.1 MPa. It is shown that the Burgess and Wheeler rule, implying a linear dependence of the lower flammability limit on the initial temperature with the intersection of the temperature axis at the point 1300$^\circ$C, does not hold for N$_2$, CH$_3$OH, CH$_2$O, and CH$_4$. For these substances, the intersection of the temperature axis is at the point 900 $\pm$ 20$^\circ$C. The Burgess and Wheeler rule gives overestimated values of the limit which do not reflect the true conditions of explosion safety.