Under Note Q, LBP fibress must contain more than 18 weight-% alkali metal or alkaline earth oxides and meet requried low biopersistence criteria. The most commonly known example of LBP fibres are AES fibres, which consist of amorphous fibres produced by melting a combination of CaO-, MgO- and SiO2 (see also EN 1094-1; VDI-recommendation 3469, Parts 1 and 5; per ECFIA website ).
How is Superwool XTRA different than Superwool Plus and Superwool Prime?
Not all low biopersistent fibres are the same.
Superwool Plus and Superwool Prime, both an Alkaline-Earth-Silicate (AES) fibre, and Superwool XTRA is a Potassium-Aluminosilicate (PAS) fibre. Both are low biopersistent.
Superwool XTRA fibres do not form crystalline silica at any stage
Does Superwool XTRA form crystalline silica?
Due to the unique fibre chemistry, Superwool XTRA does not form crystalline silica. Extensive testing, over 7000 hours at 1250°C, show no formation of crystalline silica.
How do you explain the thermal expansion and shrinkage of Superwool XTRA?
With Pyro-Bloc Modules and Pyro-Stack Modules, due to the unique fibre chemistry, the shrinkage is permanent and only happens on the first firing and when the material transforms from amorphous state to crystalline. The thermal expansion is a fundamental material property and it is a function of temperature and will continue to occur in every heating cycle and the shrinkage gaps close.