Fire Retardant Application
Fire protection sealing in general
The fire protection products can be divided into two areas: passive and active protection.
Active fire protection comes into operation when the fire is already under way, typical examples are sprinklers or fire extinguishers.
Passive fire protection concerns preventing fire and reducing the danger. It must be considered during the planning and construction phase of the building. Also passive fire protection can be split in two areas. The first is preventing the formation of fire. It describes the flammability of materials, starting from the flammable classes (easily flammable → normally flammable → not easily flammable) to non-flammable classes, which are covered usually by inorganic materials like mineral wool and concrete based products.
The second area of passive fire protection describes the safety level of a system. The system should limit the expansion of the fire and ensure the safety of escape routes for a certain time, which is long enough to evacuate the people. Typical application fields are joints, bulkheads or any other connections between rooms and floors, usually within the building and very seldom to the outside.
Classification of building materials
The degree of safety is indicated by a figure behind a letter, which says how many minutes the fire, heat and also the smoke will be retarded. Typical classifications are e. g. „EI 90“ or „EI 120“, depending on the function and the kind of closure (e. g. around pipes or wires, open joints, doors etc.).
Fire protection PU foams
PU foams are basically flammmable, depending on the formulation and the conditions they can cover all three flammable classes. Very few countries in the world regulate the flammability of sealant materials, so the by far most applied PU foams do not match any fire classification, which means they are in class „B3“ to German DIN 4102 or „F“ to EN 13501.
The fire rated PU foams, recognizable on claims like „F 240“, are usually tested in joints. A specification like F 240 says, that this product passed a fire test for 240 minutes under certain test conditions, which must be mentioned in the corresponding documents. This condions are – in case of a joint sealant foam – the width of the joint and the depth of the wall. The smaller the joint and the thicker the wall, the higher the fire resistance time for a given sealant. Often the test setup consists of a combination with non combustible materials like mineral wool, where the foam mainly prevents the penetration of smoke and the mineral wool protects the foam from the fire.
Silicone and silicate based thermoresistant sealants
Makroflex silicone sealant with higher thermoresistance can tolerate temperatures up to 300°C, the silicate based sealant up to 1200°C. While the silicone sealant remains elastic within the provided temperature range, the silicate based sealant is much harder and rigid.