If you’re reading this blog, you’ve already watched our demonstration of a specimen of Kingspan Kooltherm K15 Rainscreen board, Kingspan’s range of phenolic insulation, being subjected to the heat from a radiant heat panel in an indicative ISO 5660-1 test. If you haven’t, you can watch it here
In a nutshell, the video shows that Kingspan Kooltherm K15 Rainscreen Board self-extinguishes once the heat source is removed. In this post we will define the term self-extinguishing, discuss the characteristics you’d expect to see from a self-extinguishing material and look at video evidence to support this.
So what does self-extinguishing actually mean?
McGraw-Hill Dictionary of Scientific and Technical Terms defines self-extinguishing as ‘the ability of a material to cease burning once the source of the flame has been removed’.
As per the definition, for materials that self-extinguish such as phenolic insulation, you would expect to see any flames cease once the flame source has been taken away. In contrast, for materials that don’t self-extinguish, such as polyethylene, you would expect to see the material sustain a flame after the flame source has been taken away.
To demonstrate this we carried out our own indicative ISO 5660-1 (cone calorimeter) tests using a specimen of polyethylene, and a specimen of Kingspan Kooltherm K15 Rainscreen Board.
The first indicative test examines the behaviour of the polyethylene specimen. As soon as the specimen is exposed to the heat from the radiant heat panel it starts to melt and then at around one minute, two seconds, it ignites. When the radiation shield, used to protect the specimen from the radiant heat panel, is returned above the polyethylene test specimen at three minutes to mark the end of the test, you can see that the flames are sustained. This type of behaviour is typical of materials that do not self-extinguish. Upon completion of the test, the polyethylene specimen has completely thermally decomposed. All that remains is the aluminium foil used to wrap the specimen at the start of the test.
The second indicative test examines the behaviour of the Kingspan Kooltherm K15 Rainscreen Board specimen. Approximately 22 seconds into the test, the heat from the radiant heat panel causes the test specimen to ignite. As char begins to form on the surface of the test specimen, the flames begin to die down. When the radiation shield is returned above the test specimen at three minutes, five seconds to mark the end of the test, unlike the polyethylene test specimen, the phenolic specimen self-extinguishes almost immediately.
Below you can see a still image of the Kingspan Kooltherm K15 Rainscreen Board specimen after it has been removed from the specimen holder. Unlike the polyethylene specimen, also shown below, which underwent complete thermal decomposition, the phenolic specimen has charred on the surface, however, it has maintained its structural appearance.
The indicative tests demonstrate the complexities surrounding reaction to fire
Whilst both materials are considered “combustible”, only the Kingspan Kooltherm K15 Rainscreen Board test specimen ceases flaming once the heat source is removed, the polyethylene test specimen does not.
As such, only the Kingspan Kooltherm K15 Rainscreen Board is, by definition, self-extinguishing.