Reaction to fire - how does phenolic insulation compare to rock mineral fibre?

12 August 2019 Kingspan Insulation UK
BS 8414

 

In order to compare the reaction to fire of a ‘combustible’ product vs. a  ‘non-combustible’ product, we ran a series of our own indicative ISO 11925-3 tests. You can watch these tests here or below. 

The first indicative test looked at the behaviour of Kingspan Kooltherm K15 Rainscreen Board, a phenolic, fibre-free rigid thermoset material, recognised as ‘combustible’. The second test looked at the behaviour of a rock mineral fibre insulation with a density of 40kg/m3 + 100kg/m3, recognised as ‘non-combustible’. To compare the reaction to fire of these two insulation products, we used the observations described in ISO 11925-3 section 17, outlined in the bullet points below:
  • flame source used;
  • flame application time;
  • face or edge exposure;
  • whether a sustained ignition or transient ignition occurred;
  • whether debris separated and whether it flamed / glowed (the possibility of the material causing secondary ignition of other materials is considered by the observation of burning droplets or debris which may be formed); and
  • whether flaming reached any edge during application of the ignition source / within 4 s of the end of the flame application time.
In both tests a ‘roofers torch premixed flame source’ was directly impinged upon the face of the test samples for 3 minutes. This type of heat source gives out the most onerous kW/m2 compared to other heat sources referenced within ISO 11925-3.

Flaming debris is described in ISO 11925-3 as matter flowing or separating from the specimen and falling below the initial lower edge of the specimen and continuing to flame as it falls. You can see from the video footage that at no point during either of the tests does falling debris (flaming or glowing) occur.

You can also see that during both tests, flaming (or glowing) does not reach any edge during application of the ignition source or within 4 s of the end of the flame application time. This shows that neither material propagated the flame produced by the heat source.   

Sustained ignition is described in ISO 11925-3 as the presence of a flame on the surface of the specimen that persists for at least 4 s after withdrawal of the ignition source.
Transient ignition is described in ISO 11925-3 as the appearance of flashes, or flames, which are not sustained for a continuous 4 s after withdrawal of the ignition source.
In both tests any visual flaming ceases immediately after the ignition source is withdrawn from the face of the test sample and therefore neither sustained or transient ignition is observed.

At the end of the videos you can see that the physical characteristics of both samples are very similar in appearance; both have visible marks where the ignition source impinged upon the samples however the integrity in both instances has not been compromised.

The similarities can be further observed when the samples are cut in half. In both instances it is visible that the surface of the material has protected the ignition source penetrating through to the reverse side of the material.

So, despite one product being recognized as “combustible” and the other being recognized as “non-combustible”, the performance of both products under ISO 11925-3, using the roofers blow torch, are comparable. 

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