Intumescent 2
Intumescent 2 : Types: (1) Soft Char: These intumescents produce a light char, which is a poor conductor of heat, thus retarding heat transfer. Typically, these materials contain a significant amount of hydrates. As the hydrates are spent, water vapour is released, which has a cooling effect. Once the water is spent, the insulation characteristics of the char that remains can slow down heat transfer from the exposed side to the unexposed side of an assembly. Soft char producers are typically used in thin film intumescents for fireproofing structural steel as well as in firestop pillows. Typically, the expansion pressure that is created for these products is very low, because the soft carbonaceous char has little substance, which is beneficial if the aim is to produce a layer of insulation. (2) Hard char: Harder chars are produced with sodium silicates and graphite. These products are suitable for use in plastic pipe firestops as well as exterior steel fireproofing. In those applications, it is necessary to produce a more substantial char capable of exerting quantifiable expansion pressure. In the case of firestops, a melting, burning plastic pipe must be squeezed together and shut so that there will be no opening for fire to propagate to an otherwise fire-resistance rated wall or floor assembly. In the case of exterior fireproofing, a hydrocarbon fire must be held off with quite potentially more kinetic energy than a house fire. Intumescents that produce hard chars are unsuitable for interior spray fireproofing
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