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| Most of the products in the UK used for Passive Fire Protection (PFP) are tested in accordance with BS476. This is required by Document B and it also gives the details of the two fire types, cellulosic and hydrocarbon. A third type of fire is coming into widespread use in the oil and gas industry, which is known as ‘jet-fire’. The differences’ rest in the rate of heat rise and temperature achieved during the test period. Testing laboratories can undertake two types of test: Full Test - to actually check the performance against a required standard. This test is what the manufacturer basis his claims on in the market place, and is done to determine performance against a standard, or to a pass or fail criteria. Indicative Test - to indicate to a client the likely performance of a product. Manufacturers use this type of test usually as part of a product development programme to check performance in an official furnace. A full report will be issued and will give the results, good and bad. Care must be taken to ensure that test data is appropriate and valid for the proposed use, the only way to do this is to contact the manufacturing Company for a copy of the completed full test report. The requirements of BS476 can be subdivided into two parts: The first part refers to the ‘Reaction to Fire’ of products or assemblies. This is the extent to which a product burns and contributes to the development of the fire. The second part refers to the ‘Resistance to Fire’ which is the ability of a product to prevent the spread of flame and/or smoke, and where relevant to maintain mechanical stability. The various parts of the standard can be put into these two categories as follows:- Reaction to Fire Tests Part 3 External fire exposure roof test Part 4 Non-combustibility test for materials Part 6 Method of the test for fire propagation for products (description of how the test should be done) Part 7 Surface spread of flame for materials Part 11 Method of assessing the heat emission from buildings All these tests show how a product reacts when exposed to flame or heat. They do not show that a product has any fire resistance. The tests listed are those most commonly used. One area giving considerable confusion is the term “Class O Surface Spread of Flame”. It should be noted that:- (i)Class O is not a classification in any British Standard (ii)Class O is a material/product performance classification for wall and ceiling linings. (iii)It should not be assumed that a material/product with a Class O classification is non-combustible. Class O does not imply non-combustibility or limited combustibility The most common way to demonstrate that a product is Class O rated is to show that it: (a)Gives a Class 1 result when tested in accordance with BS476 Part 7 and (b)Has a fire propagation index (I) of not greater than 12 and a sub index (Ii) of not greater than 6 when tested in accordance with BS476 Part 6 FIRE RESISTANCE TESTS Part 20 Method for determination of the fire resistance of elements of construction (description of how the test should be performed) Part 21 Method for determination of the fire resistance of loadbearing elements of construction This is the test used for steel framing sections, load bearing walls (stability), and space separating elements + integrity and insulation Part 22 Method of determination of the fire resistance of non-loadbearing elements of construction. Used to test partitions, fully or partially insulated door sets, shutters, glazed elements, ceiling membranes etc. Part 23 Method of determination of the contribution of components to the fire resistance of a structure. Suspended ceilings are tested under this section when slung from steel beams. Also intumescent seals to timber doors. Part 24 Method of determination of the fire resistance of ventilation ducts. Tests look at 3 catergories: Loadbearing the time during which the component being tested supports a given load Integrity the tested components must not allow the passage of smoke or flames Insulation measured as the rise in temperature on the non-exposed side. A rise of an average of 140ºC with a maximum of 180ºC is permitted When a product has been subjected to these tests it is properly described as “tested to BS476” and not “approved to” or “generally in accordance with”. The test shows how the product performed in the particular test on that day. If used in identical circumstances it is likely to do the same. Copies of the DETR Approved Document B (Fire Safety) are available from: Department of the Environment, Transport and the Regions Tel: 0870 1226236 |
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info@tbafirefly.co.uk |
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