Part 1: Architect’s Guide 1 - 45 Spray applied fire protection This is the most common form of protection. There are two basic sorts of product, thick film and thin film. Figure 6.2 Fire protection With thick film coatings, the spray product or coating is fibrous or paste-like. It is generally composed of mineral fibres, vermiculite, slag or gypsum, together with a binder. It is sprayed on with special equipment under wet conditions. Several layers may be necessary, which increases the drying time. Fire protection can last up to 4 hours. Thin film coatings, called intumescent coatings, have a special property - they swell heat. When cold, the film thickness is between 0.5 and 4 mm. When heated to a temperature between 100° C and 200° C, the film swells and turns into foam, reaching thicknesses of 30 to 40 mm; this protects the steel element. These paints are applied with a spray or brush and careful application of the products ensures that protection is uniform. Conserving the aesthetic appearance of the steel is the main advantage in this type of protection, which can last up to 120 minutes. Board protection Board protection is achieved by forming a casing around the steel element. This is done with mechanical fasteners (screws, staples) or adhesive. The boards are made of gypsum, vermiculite, mineral fibre or calcium silicate compounds. The principle consists in. The passage of hot gases into the joints is a risk and requires special attention during application. This solution must be very carefully applied. Performance may reach R120.
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