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Passive fire protection is an integral part of fire prevention and suppression within industrial and commercial buildings. Many different methods can be used to incorporate passive fire protection into buildings one of which is Intumescent Coatings.

What are Intumescent Coatings?

Intumescent coating is a type of paint that is used to protect steel from heat in the event of a fire. When a fire occurs the paint heats and expands, forming a char that will protect the steel underneath for a certain amount of time.

What is the purpose of intumescent coating?

Within large buildings structural steel must be protected from fire for as long as possible to aid the safe escape of any occupants.

When steel is heated to temperatures greater than 550° it begins to lose its structural integrity which can lead to a building collapse. Intumescent protection used on steel is generally a thick, opaque substance that is then painted with a thin fire retardant coat that looks similar in appearance to gloss paint.

Epoxy or acrylated rubber are the most commonly used materials for the final coating and this is put on with airless spray to provide a smooth finish that will remain stable when temperatures change.

The thickness of the dry film which covers the steel must be measured accurately in order to be at its most effective. Several coats may need to be applied before the correct thickness is reached.

In the event of a fire intumescent coatings will react when the heat reaches 250° or more at which point it will swell to more than fifty times its original thickness and will form a ‘char’ or carbonaceous foam that protects the steel.

How does Intumescent coating work?

Intumescent coating incorporates a char reinforcing pigment, an acid catalyst such as ammonium polyphosphate, a blowing agent such as melamine, an organic binder and a carbonific.

In the event of a fire the binder will melt and the blowing agent allows gases to be released which causes a controlled expansion. In addition the inorganic materials within the substance fuse causing a char to be formed.

The use of intumescent coatings as part of passive fire protection within structures means that steel can be used in new construction without it becoming a safety risk. In the event of a fire protection such as this can prevent a building collapse or significantly slow a building collapse to help protect the safety of people inside the building and give occupants more time to evacuate in the event of a fire.

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