Fire Behavior of Low Smoke Acidity PVC Compounds for Electrical Cables, I: Focus on Flammability and Smoke

Regulation (EU) No 305/2011 [1] lays down harmonized conditions for marketing construction products in the European Union (EU) such as cables permanently installed in buildings. One of the seven basic requirements of the CPR is safety in case of fire and construction products must meet certain specific requirements in terms of reaction-to-fire. Tests, requirements, marking, controls, etc. on construction products must be the same in all EU countries, according to the product standard EN 50575 [2] which defines how cables are managed from their production to placing them on the market. On the other hand, the standard EN 13501-6 [3], provides the technical standards to be performed and the requirements to be met for specific reaction-to-fire classifications. In the dissertation several compounds PVC standard, PVC low smoke acidity and halogen free for Italian CPR cables were tested. The aim is verifying their fire performances at micro combustion calorimetry (MCC) and at Cone Calorimeter at different incidental heat fluxes (35 kW/m2), near flash over conditions, and 62 kW/m2 corresponding to a fully developed stage of a fire. The study's findings highlighted that in terms of flammability measured at MCC and THR at cone calorimetry all the new generation of low smoke acidity PVC compounds are better than the HF counterparts. The only exception is M16 jacket, which showed a better FIGRA justified by a higher TTP more than its pHRR. This last consideration demonstrates that M16 burns later but developing in the end the same heat release as R16 LSA. Thanks to this behavior, M16 is the key compound that protects the more flammable HF bedding and insulation, allowing FG16OM16 to meet the requested reaction-to-fire. In conclusion, the low smoke acidity PVC compounds grant a comparable flame retardancy and even the extremely low smoke production normally obtained with HFFR.