The flammability of carpets is an important determinant of the flammability of a whole building. Carpets have a large influence on aspects such as spread of flame, smoke generation, toxic gas evolution and burning. The less flammable interior textiles, such as carpets, are, the safer it is for the entire building. The fire safety of floor coverings does not rely solely on the ease with which a carpet ignites, but also on the rate of flame spread and smoke generation. In experiments conducted by the Wool Research Organization of New Zealand (WRONZ), wool, nylon and polypropylene carpets were tested using the NBS Flooring Radiant Panel Test. The results showed that wool carpets:
- Had the lowest propensity for flame spread (as measured by
- the critical radiant flux CRF), and,
- Produced much lower levels of smoke (IWTO, 2010).
Wool carpet is naturally flame resistant, and the performance of wool exceeds that of all other commonly encountered textile fibers. This flame retardancy arises from wool’s unique chemical structure (for example, its high nitrogen (14%) and water content), which confers the following beneficial properties and behaviors.
- An extremely high ignition temperature (570-600°C).
- A low heat of combustion.
- A low rate of heat release.
- Doesn’t melt or stick upon burning.
- Self-extinguishing.
- Formation of an insulating char when it burns.
- Evolution of less smoke and toxic gases versus the combustion of most synthetic fibers.
These results were achieved using standard testing methods: ASTM E648 Radiant Panel Test, ASTM D2859 - 06 Standard Test Method for Ignition, ISO 5657:1997 – Reaction to Fire Tests, BS 4790 - Determination of flammability.
