BS 476

[jakespop]

What are main differences between Part 6 and Part 7? I can see one deals with surface spread of flame and the other with propagation but I do not have any other information to hand. I need to advise if "Altro Whiterock" board is suitable for small area of escape route. It seems the answer may be No as it is only Class 1 surface spread. Any comments appreciated.

[Auntie LIn]

Can't be a lot of help here, but as far as I remember from dealings with such tests in the dim and distant past, the Part 7 surface spread of flame test consists of a strip of the material under test probably about 1m long by about 200mm deep held vertically in a frame.   A burner is applied at one end of the specimen and the face of the sample is measured along the length and you report how far the face of the flaming travels over a given period of time.   This then allows you to determine whether it's Class 1, 2, or 3.   If it's Class 3 there is a limited range of things you can use the material for.
If it's class 2, you might just as well have a Class 3 material because I haven't found much call for Class 2.   If it's Class 1 you can use it more widely.

The Part 6 Fire Propagation test is a box - I think about 300mm cube, where the specimen under test forms one side.   From here on in I'm really hazy, but I think heat is applied within the box and a measurement is made of temperature rise within the compartment.

I know nothing of the material you're enquiring about.   Sorry!

[John Webb]

According to "Aspects of Fire Precautions in Buildings" by Read and Morris, (BRE 137, ISBN 0 85125 361, published 1988) Part 6 is a test in which a sample 225 by 225mm and up to 50mm thick is placed on one vertical side of a box interior which contains gas jets and electric heaters. A thermocouple in the vent from the top of the apparatus monitors the temperature of the gases from the box. This temperature is a measure of the contribution of the sample by comparison with asbestos specimans. 'Cone Calorimetry' was being developed in the 1990s to give a more accurate measure of the contribution of materials to a fire and may now form another part of BS476.

Part 7 has a speciman strip 925mm long and 280mm wide exposed to a 900mm square radient panel at one end of the speciman. A pilot flame is applied during the first minute of the test to the end nearest the radient panel.

Hope this helps! And may not be up to date, I have to add!

[Tom Sutton]

Check out http://www.altrowhiterockdirect.co.uk/whiterock.html.

It says Altro PVC sheeting, for instance, conforms to BS476 Part 7 1971 Class 1 Fire regulations and meets Class 0 Building Regulations where installed to a non-combustible substrate.

If you have any doubts contact the company.