Characterization of particulate from fires burning silicone fluids

The optical properties of particulate emitted from fires burning two distin ct polydimethylsiloxane fluids (D-4 and M-2 or MM, where D=(CH3)(2)SiO and M=(CH3)(2)SiO2)were obtained using a transmission cell-reciprocal nephelome ter in conjunction with gravimetric sampling. The specific absorption coeff icient of particulate ash from fires burning D-4 and MM is significantly lo wer than that of particulate soot from an acetylene (hydrocarbon) flame. Sc attering is the dominant part of extinction in fires burning the silicone f luids. This is very different from extinction by soot particles in hydrocar bon fires, where absorption is approximately five times greater than scatte ring. Temperatures and particulate volume fractions along the axis of a sil icone fire (D-4) were measured using multiwavelength absorption/emission sp ectroscopy. The structure of the D-4 flames is markedly different from hydr ocarbon flames. The temperatures and particulate volume fractions very clos e to the burner surface are much higher than in comparably sized hydrocarbo n flames.