ON THE THERMAL RUNAWAY OF COMBUSTIBLE FLUIDS IN LAGGING MATERIAL

This paper presents the mathematical foundations for a simple theory f or investigating the phenomenon of ignition of flammable fluids in lag ging material that are used for insulation of hot pipework, for transp ort of heat transfer fluids, or other similar situations. Experiments with porous material impregnated with a flammable fluid have simulated the self-heating known to occur when combustible liquids leak from a hot pipe into lagging surrounding the pipe or are split from another s ource on to the lagging. A theory to explain these findings is present ed which shows that there is a watershed temperature beyond which subs tantial self-heating will take place. Although the theory does not tak e account of diffusion, it simulates the main physics of the phenomeno n-that is, combustible fluid, which normally in the open air would eva porate and not be a hazard, can, within a porous medium, remain disper sed within the porous structure long enough for the exothermic oxidati on to develop into ignition.