Fire Propagation Index 2.56

[Tadees]

What does the 'score' of 2.56 mean please and how does it compare with other materials used in escape routes?  I saw this score given for composite cavity barrier.

[kurnal]

Hi Tadees
You will find much info on this if you google fire propagation index and in BS 476-6.  There is also useful information in BS9999 section 34 on what is permissible for cavity barriers and materials in concealed spaces. Hope this helps.

[Tom Sutton]

Check out http://www.firete.com/en/detail2_301.html and then in accordance with ADB escape routes should meet Class "O"

Appendix “A”

12   To restrict the use of materials which Ignite easily, which have a high rate of heat release and/ or which reduce the time to flashover, maximum acceptable 'fire propagation' Indices are specified, where the National test methods are being followed. These are determined by reference to the method specified in BS 476-6:1981 or 1989 Method of test for fire propagation of products. Index of performance (I) relates to the overall test performance, whereas sub-Index (i1) Is derived from the first three minutes of test.

13   The highest National product performance classification for Lining materials Is Class O. This Is achieved If a material or the surface of a composite product Is either:

a.   composed throughout of materials of limited combustibility; or
b.   a Class 1 material which has a fire propagation Index (I) of not more than 12 and sub-index (i1) of not more than 6.

Note: Class 0 Is not a classification identfled In any British Standard test.

As we used to say a Moreton Big I less then 12 little i less then 6 happy days.

[Fishy]

Meaningless on its own, I'd suggest, unless you know what test/classification this performance is claimed against. 

If it does refer to a BS 476:Part 6 test result of "I" = 2.56, it doesn't demonstrate Class '0' performance unless the material is Class 1 as well.