RCF, LBP and PCW: Understanding Fiber Safety Chemistries

Three fibre chemistries dominate high-temperature insulation, and each behaves differently once inhaled.

RCF (Refractory Ceramic Fibre). Typically a blend of Al2O3 and SiO2, often complemented with ZrO2 for high temperatures. RCF/ASW is classified as a carcinogenic substance (CLP category 1) and must be labelled accordingly (H350i; P202; P281).

LBP (Low Bio-Persistence). Based on alkaline earth silicates with more than 18% alkaline earth oxides (CaO, MgO, K2O), allowing exoneration testing. LBP fibres clear from the lungs rapidly, but above roughly 1050°C they can form respirable crystalline silica (cristobalite), which carries its own health risk.

PCW (Poly Crystalline Wool). A high-Al2O3 fibre range, sometimes referred to as mullite or corundum fibre. Coarser fibre diameters from the extrusion process mean PCW is inhalable but not generally considered respirable.

The HYBRID SYSTEM combines the robust, non-respirable properties of PCW on the hot face with safe LBP fibre on the cold face. The microporous interlayer keeps the LBP side below 1050°C, keeping the system RCF and RCS free.