Fire protection glass.
The fire protection glazing is divided into fire resistance classes: F 30, F 60, F 90, F 120 and G 30, G 60, G 90, G 120. These figures indicate the duration of fire resistance in minutes.
F-glasses mainly differ from G-glasses by restricting not only the fire stability but also the heat transfer by conduction, convection and radiation. F-glass consists of two pre-stressed glass panes (toughened safety glass) – 6 mm each –, a kind of pre-cast insulation glass. In exchange, the air is replaced by an organic, aqueous gel. In case of fire, the single fire-facing pane shatters. The gel now can compensate fire heat by adding water. Due to the combustion process on the surface of the fire protection coating, the glass discolours being now impermeable to radiation.
F-glass is mainly used in facades of high buildings in order to prevent flame penetration. G-glass is principally used in interiors.