Intumescent Coating

For a generation, Nullifire has been pioneering the development and use of intumescent coatings for fire protection of structural steel and timber. Nullifire systems offer the most versatile and cost-effective solutions for reliable fire protection and decoration of internal steelwork. These include a complete range of water-based coatings that provides 30, 60, 90 and 120 minutes fire protection to universal beams, columns, hollow sections, as well as cellular beam designs.

Product Groups:

System S: For structural steel protection

System W: For timber substrate protection

What are intumescent coatings?

Intumescent coatings provide an appearance similar to that of a paint finish. At ambient temperatures, they remain stable. However, in a fire situation, the increase in temperature causes a chemical reaction.

The intumescent coating expands to many times its original thickness. This provides an insulating foam-like coating or "char" which protects the substrate.

Protecting steelwork

The intumescent coating is designed to insulate the steel, and prevent the temperature of the steel from rising to a critical point at which structural failure becomes possible.

Protecting timber structures

Timber structures are more susceptible to the surface spread of flame and heat propagation. Intumescents are designed to reduce heat propagation, and reduce the spread of flame.

How do intumescents work?

The expansion process is caused by the interaction of three precisely formulated components:

• Carbon supplier: polyols as starch, pentaerythritol
• Acid source: ammonium polyphosphate
• Expanding agent: melamine

NOTE: These components are bound in a solvent or water-borne polymeric binder. Other components are added to improve the paint properties, enable easy application, enhance build and achieve faster drying.

Typical intumescent process

As heat is applied the chemical reaction begins:

• The heat begins to soften the polymeric binder
• It also causes an organic acid to be released from the Ammonia Polyphosphate
• Carbonisation of the polyols begins
• As the blowing agent (melamine) decomposes, gas is produced which swells the molten mixture
• Finally, the foamed char solidifies, through a cross-linking reaction, to maintain the insulation

In an ideal situation, intumescent can expand to around 100 times its original thickness. To achieve this requires careful selection of formulation components and precise matching of processes involved.

For further information please contact Nullifire Technical Services Department:

Tel: 024 7685 5000

Email: protect@nullifire.com

For guidance on which Intumescent Coating to use go to our Product Selector page.