Fire test methods products/materials

Fire test methods attempt to provide correct information on the fire contribution of a product by exposing a small sample to conditions expected in a fire scenario. Methods can be viewed in two ways the first entails the strategy of the fire test, ignition resistance or low flammabiUty once ignited the second addresses the test specimen, a sample representative of the product or a sample of a material that might be used in the product. Fire science has progressed markedly since the older test methods were developed and it is known that the basis for many of these tests is doubthil. Results from older tests must be used with great care. 

Fire tests on building materials and structures. Part 12 Method of test for igmtability of products by direct flame impingement. Replaced BS 476 Part 5 1979 AMD 1 Fire tests on building matenals and structures. Part 20 Method for determination of the fire resistance of elements of constiaiction (general principles) (AMD 6487) dated 30 April 1990. Replaced BS 476 Part 8 1972... 

There are no ISO, ASTM or British fire test method standards specifically for solid mbbers and there is no active fire test work being pursued in TC 45. There are, however, a number of published international test methods for cellular materials and plastics, the majority of which could be applied to rubbers. A comprehensive account of fire testing of plastics has been given by Paul in the Handbook of Polymer Testing81. There may be fire resistance requirements for particular rubber products and some examples were given by Schultz110. 

As discussed earlier, a number of organizations and technical committees develop fire-test methods or specifications that are specific to some particular material or product. It is not possible to cover all of them in this work and they are usually publicly available from the responsible organization via their website. 

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

The severity of the exposure and the time a specimen is exposed to the ignition source are the main differences between the tunnel test methods. The 25-ft tunnel test is the most severe exposure and the specimen is usually exposed for 10 min. An extended test of 30 min is performed on fire-retardant treated products. Materials that pass the extended test (have flame spread less than 25 with no evidence of glowing) qualify for a special FR-S rating. Because the 25-ft tunnel test is the most severe exposure it is used as the standard for building materials. The 2-ft tunnel test 17, 18) is the least severe. Because of the small specimen size required with this test, it is a valuable tool for development work on fire retardants. The 8-ft tunnel falls between the 2- and 25-ft tunnels in severity. It can be a valuable... 

The assessment of the contribution of a product to the fire severity and the resulting hazard to people and property combines appropriate product flammabihty data, descriptions of the building and occupants, and computer software that includes the dynamics and chemistry of fires. This type of assessment offers benefits not available from stand-alone test methods quantitative appraisal of the incremental impact on fire safety of changes in a product appraisal of the use of a given material in a number of products and appraisal of the differing impacts of a product in different buildings and occupancies. One method, HAZARD I (11), has been used to determine that several commonly used fire-retardant—polymer systems reduced the overall fire hazard compared to similar nonfire retarded formulations (12). 

It is the general consensus within the worldwide fire community that the only proper way to evaluate the fire safety of products is to conduct full-scale tests or complete fire-risk assessments. Most of these tests were extracted from procedures developed by the American Society for Testing and Materials (ASTM) and the International Electrotechnical Commission (IEC). Because they are time tested, they are generally accepted methods to evaluate a given property. Where there were no universally accepted methods the UL developed its own. 

There is no standardized test method for determining the combustion products given off from wood or other materials during a real fire situation. The gases and products obtained and their estimated hazard to life will depend on the experimental conditions of any test method selected. Most studies on the toxicity of combustion products show that the dominant hazardous gas from burning wood is carbon monoxide followed by carbon dioxide and the resulting oxygen depletion (46-50). 

In some cases, it is not possible to evaluate a material or product (combination of materials) in a bench-scale test in a manner that is representative of its end-use. For example, it is difficult to use a bench-scale test method to evaluate the effect of joints on the fire performance of a thick sandwich panel that consists of a plastic foam core and metal skins. In this case, a room test is used to assess the reaction to fire of the materials. It is also very difficult to assess the fire performance of complex objects such as upholstered furniture based on the reaction-to-hre characteristics of the object s components. Large-scale reaction-to-hre tests have been developed to evaluate these complex objects. 

Static smoke chamber methods have major limitations in terms of being indicative of the fire hazard due to smoke toxicity of products and materials in actual fires. As combustion products accumulate in the chamber during a test, the burning behavior of the test specimen may have a significant effect on the level of vitiation (oxygen concentration) and temperature rise in the chamber. 

ASTM E 1623 Test Method for Determination of Fire and Thermal Parameters of Materials, Products, and Systems Using an Intermediate Scale Calorimeter (ICAL). ASTM International, West Conshohocken, PA. 

The range of toxicity test methods is bound to produce different fire conditions, and hence different toxic product yields. Four test methods (NBS Smoke Chamber, NF X 70-100, Fire Propagation Apparatus [FPA], and SSTF) have been compared, primarily from published data64 66 using the carbon monoxide yields and hydrocarbon yields (not recorded in the NFX tests), which are both fairly good indicators of fire condition, for four materials (LDPE, PS, PVC, and Nylon 6.6), at two fire conditions, well-ventilated and under-ventilated. The CO and hydrocarbon yields are shown in Figures 17.9 and 17.10. 

Within ASTM, technical committees associated with plastics, electrical materials, textiles, protective clothing, thermal insulation, consumer products, detention and correctional facilities, and ships have developed tests that are often application tests that are of specific interest to the products involved. One fire test has spawned more application standards than any other, primarily because of its vast use in the United States ASTM E 84 (Steiner tunnel). Thus, NFPA 262, UL 1820, UL 1887, ASTM E 2231, ASTM E 2404, ASTM E 2573, ASTM E 2579, and ASTM E 2599 are all test methods and practices based on the Steiner tunnel test. In some cases, the base apparatus is being modified (although usually it is permissible to conduct the ASTM E 84 test in the apparatus of the other test, but it is often not permissible to conduct the other test in any apparatus complying with the ASTM E 84 apparatus). The other test method that has resulted in many application standards is the cone calorimeter the standards are ASTM D 5485, ASTM D 6113, ASTM E 1474, ASTM E 1740, and ASTM F 1550. 

ASTM E 814 Standard Test Method for Fire Tests of Through-Penetration Fire Stops ASTM E 906 Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products... 

ASTM C373-88. (2006) Standard Test Method for Water Absorption, Bulk Density, Apparent Porosity, and Apparent Specific Gravity of Fired Whiteware Products, American Society for Testing Materials. 

Although the Factory Mutual Apparatus [101] has never been proposed as a standard test method, it is briefly mentioned here since it has been used for basic research work by several organizations and contains a number of novel features. A 100 mm. square specimen is mounted in a vertical chimney and heated (up to 65 kW m") by banks of quartz lamps mounted outside the chimney. Preheated air or oxygen nitrogen mixtures are pa.ssed up the column at a constant rate. The apparatus has been mainly used to determine the fundamental fire properties of materials, although products such as cables have also been tested. 

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