EN ISO 11925-2:2010, also known as the single-flame source test or ignitability test, is a small-scale reaction to fire
test . It is designed to determine the ignitability of a product by directly exposing a vertically oriented sample to a small-flame. It is one of the tests used as part of the Euroclass system
How does the single-flame source test work?
The test is conducted within a stainless-steel walled combustion chamber which is 50 mm in height and has an open square area of 25 mm x 25 mm. The chamber has heat resistant glass doors on its front and at least one side for access and observation. To allow free ventilation, the chamber sits on 40 mm high supports which provide an air gap on the lateral side.
A flat test specimen measuring 250 mm x 90 mm and no greater than 60 mm thick is clamped in a vertical U-shaped holder. Samples can either be tested for surface exposure, edge exposure (this includes single-layer or multilayer), or both. For every test orientation, a minimum of six specimens shall be tested.
A propane gas burner is mounted at a 45° angle so that its flame application is:
• 40 mm above the bottom edge of the sample (surface exposure);
• at the mid-point on the bottom of the sample (edge exposure on samples ≤ 3 mm thick);
• 1.5 mm behind the surface (edge exposure on samples > 3 mm thick); or
• at the bottom edge of the centreline of the underside of each different layer with the test specimen turned at 90° round its vertical axis (edge exposure on multilayer samples > 10 mm thick).
Filter paper is placed below the sample to collect flaming droplets/particles.
For every test orientation, a minimum of six specimens shall be tested. Typically, 6 – 18 samples are tested individually.
It is recommended that a minimum of six specimens are tested against each ignition source and for each ignition time: three for surface ignition; and three for bottom ignition.
The burner is lit with a flame height of 20 mm and the test begins as soon as this makes contact with the sample. The flame can either be applied for:
• 15 seconds (with the sample observed for a further 5 seconds); or
• 30 seconds (with the sample observed for a further 30 seconds).
During the test, the flame height is measured as is occurrence and duration of any flaming particles.
The result is given as the maximum flame height from the required amount of specimens within that test.
How is the single-flame source test used to classify products within the Euroclass system?
The single-flame source test is used within the Euroclass system for product classes B – F.
Products are tested for surface exposure alone if they will be used in applications where direct flame impingement on the edge of the product cannot occur (such as flooring). If edges can be exposed, then both surface and edge flame arrangements are used.
The criteria used according to BS EN 13501-1:2018 depend on the level of classification:
Euroclass B – D: 30 second exposure with flame height not exceeding 150 mm within 60 seconds (To attain these classifications the products must also meet certain performance criteria when assessed under the Single Burning Item (SBI) test – EN 13823.
Euroclass E: 15 second exposure with flame height not exceeding 150 mm within 20 seconds.
Euroclass F: If any specimen fails to obtain class E.
You can download the full testing standard from your local National Standards Body.