When sealing the opening with panels of fire resistant stone wool, the maximum number of dampers also subject to the maximum surface or “blank seal” allowed for the selected sealing material. What is the "blank seal"?

The blank seal is the maximum aperture that can be sealed using stone wool boards from that manufacturer. The size of the blank seal is brand specific (for ex. Promat WxH ≤ 3,75 m², Hilti EI90S ≤ 3,20 m², Hilti EI120S ≤ 1,44 m²). Please refer to the manufacturer for more information.