Understanding reaction to fire
An important aspect in evaluating the fire safety of a facade is the understanding of the reaction to fire classification. In all national building regulations throughout Europe, this is a corner stone with respect to material selection.
The importance of fire tests
Reaction to fire of a product and a construction is a way to evaluate the contribution a material can have on fire growth and development, which is particularly important in the early stages of a fire. The reaction to fire classification of building materials is determined through a series of tests which measure performance against several key characteristics. In principle the better the reaction to fire classification of a product is, the better it will limit the possibility for the fire to spread further over the facade and the more time people will have to escape. The reaction to fire classification of materials is done in accordance with the BS EN 13501-1 standard. This standard determines the tests to be done for classification, the criteria and the reporting of the tests and classification. The classification system differentiates between products classified A1 or A2-s1, d0 are considered non-combustible and those classified B – F are considered combustible.
Reaction to fire tests
In order to classify the reaction to fire of a product the standard contains several tests, each covering an important part of the reaction to fire. Next to that, the standard contains for each test a set of criteria to determine the classification. There are three main aspects covered:
1. The first symbol (A1, A2, B, C, D, E or F) covers the class. A1 and A2 class are considered non-combustible were B – F are combustible.
2. The second symbol (s1, s2, s3) covers the smoke growth rate with s1 being the lowest and s3 the highest growth rate.
3. The third symbol (d0, d1, d2) covers the flaming droplets. With d0, there are no flaming droplets within the first 5 minutes, d1 means limited flaming droplets and d2 for anything else (worst score). For determining these three aspects, a series of tests are included in the standard. These tests represent an evaluation of the material in the different phases as identified in the figure below.
For determining these three aspects, a series of tests are included in the standard. These tests represent an evaluation of the material in the different phases as identified in the figure below.
Discover more about the tests: