Intraluminal flame spread in tracheal tubes.

Abstract

Intraluminal combustion in polyvinyl chloride tracheal tubes was investigated. Two flame types were observed: intraluminal and downstream. The flame-spread velocity, burning rate, and equivalence ratio of the intraluminal flame were determined. The products of the intraluminal flame were analyzed, revealing compounds capable of further combustion. Below a certain oxidant flow rate, the tubes do not ignite. At low flow rates that support a flame, the burning rate is minimal and the equivalence ratio reveals no fuel available for the downstream flame, suggesting that ignition of tracheal tubes is least likely in the absence of intraluminal flow. We conclude that the downstream flame is the flame type that is most dangerous and that the intraluminal flame is the generator of fuel and ignition energy for the downstream flame.