The influence of pressure on combustible and toxic properties of materials

Combustible and toxic properties greatly influence the application of materials in shipbuilding. These materials, especially plastics, create a serious toxic hazard during fire. Under fire conditions they decompose thermally, giving off considerable amounts of smoke and volatile toxic substances which cause a serious hazard to people overcome by fire inside a compartment.1–3Lethal poisoning by the thermal degradation products of plastics has attracted the attention of many investigators to toxic hazards during a fire.1,4 Underwater systems create, in particular, a serious fire hazard. Fire in a decompression chamber spreads in a different way to land fires and usually causes the death of the crew and complete destruction of equipment in the chamber. Theoretically, complete fire protection in a chamber could be achieved by the total elemination of combustible materials and their replacement by incombustible ones. However, from a practical point of view this is impossible. The general principles of materials selection used in underwater systems are defined by Det Norske Veritas.5 Unfortunately, these do not describe the methods of testing materials nor the criteria of materials selection. There is also a lack of information in the literature on toxic hazards under elevated pressures. This problem has been studied in detail with oxygen‐enriched atmospheres in aerospace programmes,6 but because those studies are classified there is only fragmentary information in the literature.