A2 Euroclass vs B Euroclass. Which requires less flame spread?

In the post that I present to you today, I am going to tell you a situation that happened to me during a course that I gave last November.

When I was explaining the European classification system of reaction to fire (Euroclasses) and at the end of answering a question from one of the students, a colleague told me that he was going to require the products an A2 euroclass because the flame spread always it would be less than for a product with B euroclass.

This statement may sound logical for someone who does not know the classification criteria of Euroclasses but when this system is known in depth the reality is very different. To deal with this issue, it is essential to know the tests required to obtain A2 and B Euroclasses, as well as their classification criteria. Below it is shown a comparison of the current requirements for getting these euroclasses

As you can be seen, the flame spread for a A2 euroclass is evaluated through the SBI test. The flame spread must not reach the edge of the specimen of the long wing, i.e. a length of 1000 mm (This corresponds with the lateral flame spread criterion identified in the classification standard as LFS). But this requirement is exactly the same as for a B Euroclass. In fact, in the EN 13501-1 classification standard, it is explicitly stated that the criteria applicable to the SBI standard to get a B Euroclass would be the same as for a A2 Euroclass. That is, there would be no difference between the two classes in terms of flame spread requirements.

Therefore, before requiring an Euroclass, it is necessary to know the classification parameters and the criteria that it takes into account. Only in this way, it can fit the Euroclass to the required needs. Finally, the student understood that his initial idea about the flame spread was not correct.

Bibliography

EN 13501-1. Fire classification of construction products and building elements – Part 1: Classification using data from reaction to fire tests.

Diseño de Instalaciones de Protección contra Incendios (PCI)