Flame spread classification

If the pyrolysis-combustion process becomes exothermic, the flaming on the specimen becomes self-propagating, A flame-spread classification or rating number is calculated from the time-distance progress of the flame along the length of the specimen surface. 

The flame spread distance was observed and recorded every 15 seconds or every 2 feet of progression. The peak distance was noted at the time of occurrence. The flame spread distance was plotted over time. The total area under the flame spread distance-time curve was determined. The flame spread was then calculated as a function of the area under the curve relative to the standard red oak curve area. The value for flame spread classification was compared with that of inorganic reinforced cement board and select-grade red oak flooring. 

Turmel testing provides data on burning rate or combustion rate, burning extent or distance of flame travel, flame spread factor and flame height. It is a mandatory test for flooring materials and many others. Materials are rated on flame spread classification with red oak as 100 ... 

Furthermore, it has been shown that the time period until ignition occurs, in the Cone calorimeter, is proportional to the inverse of the flame spread rate [16]. The Cone calorimeter can also be used to provide the mass loss rate information required for the simplified classification into categories of toxic hazard [1] quick toxic hazard assessment. Thus, the NBS Cone calorimeter is a very useful tool to overcome some of the disadvantages associated with measuring a single property at a time. 

Test samples are preconditioned in a specified atmosphere before exposure, and the test flame exposure is continued for 10 minutes unless the sample is completely consumed before that time. Observations of the spread of flame are made at 15-second intervals during the test. If the flame spread reaches only part of the distance between the end of the test flame and the end of the sample, the percentage of the distance traveled establishes the classification. If the flame spread reaches the end of the tunnel, the percentage of the time required against the time for the red oak... 

Wood well treated with current commercial fire-retardant impregnation treatments will have flame-spread ratings of 25 or less. Many treated wood products have obtained a special marking or designation "FR-S" from UL (36) for having a flame-spread, fuel-contributed, and smoke-developed classification of not over 25 and no evidence of significant progressive combustion in an extended 30-minute ASTM E84 (34) test procedure. The fuel-contributed and smoke-developed classifications are also calculated relative to performance of red oak and asbestos-cement board. 

Some of the test methods of flame spread rate are devoted to the classification of plastics into various flammability groups. 

The flame spread index (h) has traditionally indicated a material s surface flammability. The Is terminology is, however, currently in the process of being changed to the Radiant Panel Index. The I, number of classification indicates a comparative measure derived from observations made as the flame front moves across the sample surface under defined test conditions. 

Fire testing and classification of building and other materials are based on certain flammability characteristics such as flame spread, ignition temperature, smoke development, non-combustibility, fire resistance, rate of heat release, oxygen index, etc. Some of them are briefly discussed in the following paragraphs [124-126]. 

NF P 92-503 - electric burner test. Specified in France as one of the tests for classification of building materials. A 600 x 180 mm specimen is mounted at 30° and subjected to heat from an electric burner, with a pilot flame impinging on the lower edge. The highest classification is given when the specimen flames for no more than five seconds and there is no flame spread. 

BS 476 Part 7 1987 details the method for classification of the surface spread of flame of products (and its predecessor BS 476 Part 7 1971). The test is a classification system based on the rate and extent of flame spread and classifies products 1,2, 3 or 4 with Class 1 being the highest classification. 

All important factor in assessing tlie causes and effects of fires is tlie beluivior of a fire s flmne. Knowledge of a flame s spreading rate and heat intensity can reduce fire liazard potentials and fire damage. The classifications of flame behavior are ... 

A description is given of the initiatives carried out within the European Community for the harmonization of fire testing. The technical and economic reasons are explained for such initiatives, which are taken in order to remove barriers to trade from the European internal market. Of the various fire aspects, only fire reaction testing is taken into consideration here, because it appears as a major technical obstacle to the free circulation of construction materials. All possible approaches are considered for the attainment of such a harmonization and one, the so called interim solution, is fully described. The proposed interim solution, is based on the adoption of three fundamental test methods, i.e. the British "Surface Spread of Flame", the French "Epiradiateur" and the German "Brandschacht", and on the use of a rather complicated "transposition document", which should allow to derive most of the national classifications from the three test package. 

The number of small scale test methods, used for classification purposes, should be limited and based on ISO tests, presumably the Cone Calorimeter /10/ (see Fig. 8) and possibly the ISO Surface Spread of Flame test /11/. 

BS 476 Part 7 1987 Fire tests on building materials and structures Method for classification of the surface spread of flame of products. 

There may be cases where FR additives will be required in order to pass severe fire specifications, like the Ml classification of ihe French Building Standard using the Epiradiateur Radiation Test. Also, under the EU Building Products Directive there is now a move to harmonise national fire legislation and testing. The new spread of flame test or SBI test may require some increase in the fire retardancy of current rigid PVC formulations. 

Few unsaturated polyester resin-based laminates can achieve better than the F2 level with most only able to reach F3. However, in recent years, developments in resin technology have resulted in Ml (the best surface spread of flame requirement in the French test, which is equivalent to BS476 Part Class 1), and FO classifications with some filled resins (Seott Bader Crystic 343A). The major limitation is a maximum fibre eontent, by weight, of just 20%, which limits applications to semi- or non-struetural components only. Henee, sueh materials can be used for many decorative internal eomponents and cladding panels supporting their own weight. 

Dicyclopentadiene (DCPD) with or without a saturated polyester as a low smoke low profile additive can pass various building fire tests such as the German Chimney test or the British and French spread of flame tests at the highest or next but one classifications. Likewise an unsaturated polyester blended with methyl methacrylate can achieve such levels with either 120 phr of APP, 225 phr ATH and 25 phr APP, or with 300 phr of ATH. Similar formulations also pass German and US railway tests with 100 phr of ATH and 10 phr APP. Not only are these formulations highly flame retardant but they also fulfil smoke density and toxicity requirements as severe as those demanded by the aircraft industry. 

Scandinavia Nordtest NT Fire 004. The test is designed to measure the ability of floor covering to resist fire spread and smoke development, a flaming wood crib is placed on a 1000x400 mm specimen. After 15 seconds the blower and suction fans are switched on to give a specified airflow. Highest classification... 

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