Fire performance of phenolic insulation

30 April 2020 Kingspan Insulation New Zealand

What is phenolic insulation?

Phenolic insulation is rigid insulation with a closed-cell structure. It is made by mixing phenolic resin with a catalyst and a blowing agent. This mix is then added directly to the bottom layer of the facing and due to a chemical reaction between the ingredients in the mix, it expands to meet the top layer of the facing. The chemical reaction releases heat and causes a network of bubbles to appear as the blowing agent is vaporised in the material, which locks in the gas and contributes to the thermal performance of the finished product. Once the boards are formed, they are cured and dried in an oven. After they are taken out of the oven, the boards are cut to size and packaged up.

Benefits of phenolic insulation

Phenolic insulation is the most thermally efficient insulation commonly used. Thermal conductivity of phenolic insulation is much lower than other insulation materials such as EPS, XPS, PIR or mineral fibre products. That is why phenolic insulation can help you achieve a required thermal performance in a much thinner profile than other insulation materials. Furthermore, phenolic insulation can be used in a variety of roof, wall and floor applications, which makes it a great solution for a range of constructions.

Fire performance of phenolic insulation

Besides advanced thermal properties, phenolic insulation has exceptional fire performance, demonstrating low flame spread and smoke emission. Since it is a thermoset material, it hardens and chars in fire situations, giving off very little smoke; unlike thermoplastics, such as polystyrene which melt, soften, and give off thick black smoke.

To better demonstrate the fire performance of Kingspan Kooltherm phenolic insulation we have put it to the test in the following video:

In the video you can see a sample of Kingspan Kooltherm insulation being subjected to a blow torch flame. Kooltherm insulation chars when it is burnt which stops it from propagating fire and once the fire source is removed, it self-extinguishes.

The heat from the flame causes the insulation to undergo pyrolysis, which results in the black char that is formed on the surface of the board. The pyrolysis also releases combustible gasses, which cannot be seen, but the result of their subsequent combustion can, in the additional flames the occur. These additional flames are most obvious in the first 30 seconds after the blow torch flame is introduced, whilst the initial char is formed. After this, the flames die down a little, and the amount of char gradually increases.

After 8 minutes the blow torch is removed, and you can see that the board itself does not propagate flaming across its surface without the blow torch flame, and that the board self-extinguishes. That happens because when the blow torch flame is taken away, the energy from combustion of pyrolysis gases alone is insufficient to support further pyrolysis, and the insulation self-extinguishes.