Flammability Tests -4.
Flammability Test Methods:
NFP 92 - 503 - Bržleur ƒlectrique
The French test known as the "Bržleur ƒlectrique" - electric burner - is the principal method used not only in France, but also in Belgium, Spain and Portugal. It results in a classification of M1 to M4, with M1 being the highest classification.
The sample is placed face down on the test rig at an angle of 30o above an electric radiator which gives out heat. A small butane gas pilot flame is applied directly to the fabric surface at 20 seconds into the test, held in position for 5 seconds then withdrawn. The flame is applied again at 45 seconds and subsequently every 30 seconds for the duration of the 5 minute test. If any flaming continues after 5 minutes, the test is continued until the specimen extinguishes completely.
The following aspects are noted during the test:-
- duration of flaming
- production of burning droplets
- length/width of the damaged specimen
Actual classification requirements are given below:-
|Duration of Combustion||s||<=5||>5||>5||>5|
NFP 92-504 - Rate of flame spread test
This complimentary test to the Electric Burner helps establish a classification on samples which behave unusually during the primary test - for example, melting rapidly or shrinking away to form a hole so that the pilot flame cannot come into contact with the sample at 20 seconds, or if samples were unable to achieve an M3 rating.
For materials which melt or shrink away from the heat source, after flame, non-propagation of flame and burning/non burning droplets are observed. Rate of flame spread is also measured if the material does not achieve M3.
The non-propagation of flame test involves a flame being held against the free end of a horizontal sample, 10 times for 5 seconds; the time of after flame is measured.
In the flame spread test, the time taken for flame to spread between two reference marks at 50mm and 300mm is established. The production of burning droplets is also noted.
Classification criteria are given below:-
|Classification||M1||M2||M3 a||M3 b||M4|
|Duration of Combustion||none||<5s||<5s||>5s||>5s|
|Droplets||None or non burning||None or non burning||Burning||None or non burning||Burning|
NFP 92-505 - Dripping test
Again complimentary to the electric burner, the dripping test is employed to investigate further into the potential hazard of burning droplets observed during the primary test.
A sample is placed on a grid 30mm below a radiator and a receptacle containing cotton wool is positioned 300mm below the grid. Heat is applied from the radiator for 10 minutes and the test is repeated 4 times. If the cotton wool sets alight, the fabric is classified M4. If it does not ignite, even if flaming or molten drips are produced from the sample, the original classification from the electric burner test is retained.