Kilargo Intumescent Fire Dampers are available in a range of sizes and can also be made to measure. They comprise a series of parallel intumescent slats reinforced with impact-resistant steel edging, all housed in a rigid steel framework. They allow air to pass freely through a duct, under normal conditions. In the event of a fire, heat will cause the intumescent slats to activiate and swell to many times its original thickness to form a solid barrier to fire, smoke and gases.
Product MSDS and downloads available here