Laboratory flammability tests

Flammability of polymers is assessed primarily throngh ignitability, flame spread, and heat release. Depending on the application of the polymeric material, one or more of these flammability criteria should be measured in appropriate flammability tests. Numerous flanunability tests are known and are performed either on representative samples or on an assembled product. Tests can be small, intermediate, or fiiU scale. Although similar trends in the rating of materials can be found based on small- and large-scale tests, in general there is no direct correlation between these tests. 

International and national standards have been developed based on various flanunability tests, and they are reviewed elsewhere. Some relatively simple and inexpensive laboratory tests have found broad application. These tests are used primarily in industrial laboratories for screening of materials during product development or quality control, or in the academic community for studies of polymer flanunability. In this chapter we describe some of the commonly used laboratory test methods. 

Underwriters Laboratories UL-94 test is designed to assess the flammability of plastic materials for parts in devices and appliances. The test measures ignitability and flame spread of polymeric materials exposed to a small flame. It is accepted for standardization in many countries and also internationally. Five 

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One of the most useful laboratory flammability tests is the oxygen index (Of) test (ASTM D-2043 and ASTM D-2863). In this test, the polymer is burned by a candle in controlled... 

Flame Resistance. Traditionally, small-scale laboratory flammability tests have been used to initially characterize foams (38). However, these do not reflect the performance of such materials in bulk form. Fire characteristics of thermal insulations for building applications are generally reported in the form of qualitative or semiquantitative results from ASTM E84 or similar tunnel tests (39). Similar laiger scale tests are used for aircraft and marine applications. 

Laboratory Flammability Tests for Wire and Cable Materials.794... 

LABORATORY FLAMMABILITY TESTS FOR WIRE AND CABLE MATERIALS... 

Neville, J. A. G. Flame and fire testing of cables with particular reference to PVC. Symposium on Fire Protection of Cables. The Electrical Research Association, London 1972, p. 99 Woollerton, G. R. A small scale laboratory flammability test for electronic components. J. Fire and Flammability, 12, 89 (1980)... 

Underwriters Laboratories (UL) Test 94 can be used. The placement of the specimen, the size of the flame, and its position and location with respect to the specimen are described in detail in this important UL specifications. Depending on their nonburning to burning capabilities, results of tests are reported as being materials classed 94V-0, 94V-1, 94V-2, 94-5V, etc. (Chapter 2, HIGH TEMPERATURE, Flammability). 

Preparation of Samples for Flammability Testing. Samples of the phosphorus containing terepolymers and of the polymer blends were converted to film by compression molding on a Carver Laboratory Press with electrically heated platens. The films were prepared at 250°C and 20,000 lb. pressure, using a 10 mil thick frame mold. Samples (2" x 1/4") were cut from this film for flammability testing. 

Underwriter Laboratories, UL94 Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, Underwriters Laboratories, Inc., 333 Pfingsten Road, Northbrook, IL, 1.6th edition, 2000. 

Testing of materials is carried out on small specimens under laboratory conditions. Their results are characteristic only of the tested polymeric material without any reference to the location and mode of its application. In the interpretation of material tests, the stage of burning of the specimen to which the results are referred should always be indicated. Flammability tests of high-temperature plastics are discussed separately. A separate section is devoted to the explosion hazard of plastics powders. 

The early organization of flammability tests in the building industry has had some disadvantages. The individual countries standardized their own methods developed in their national research laboratories, so that the principles, the dimensions of test specimens, and the rating systems of these standards differ considerably from each other. 

DeMaio and Baushke [6] used flammability tests to select elastomeric materials, which meet industry flammability standards, with the emphasis on elastomeric materials for mass transit applications and electrical applications. The intricacies of the UL 94 VO listings are briefly considered, flammability ratings for cellular silicones are tabulated and regional fire testing services and UL laboratories in the USA and Canada are listed. 

Non-flammable - fla-m3-b9l (1915) adj. If combustible, burning without flame. Practically, whether or not a plastic material or part is flammable is a matter of its performance in a test - of which there are many - of flammability. Note that the word inflammable has been deprecated by fire-safety authorities because of the ambiguity of the prefix in- , and has long been superseded by flammable and non-flammable . Tests for comparative flammability of liquids, U1 340. Laboratories Incorporated Underwriters, New York, 1997. 

The primary consensus-based organizations in the United States developing and maintaining fire and flammability test standards are ASTM International (previously the American Society for Testing and Materials) and the National Fire Protection Association (NFPA). Committee EOS on Fire Tests is the primary committee in ASTM that develops fire and flammability test standards (25). Several material- or product-oriented Committees have subcommittees that develop fire and flammability test standards as well. For example. Committee D20 on Plastics has a subcommittee on thermal properties (D20.30) that develops and maintains some fire and flammability test standards for plastics. The Fire Test Committee is responsible for all fire and flammability test standards that are used by any of the fire safety codes and standards published by NFPA. A number of test laboratories in the United States, such as Underwriters Laboratories and FM Global, have established a consensus process that meets the requirements of the American National Standards Institute (ANSI) so that they now can publish American National Standards. 

Typical Example of a Flammability Test. The UL 94 standard provides procedures for bench-scale tests to determine the acceptability of plastic materials for use in appliances or other devices with respect to flammability imder controlled laboratory conditions. The standard inclndes several test methods that are employed depending npon the intended end nse of the material and its orientation in the device. The standard ontlines two horizontal burning tests, three vertical bnming tests, and a radiant panel flame spread test. The most commonly used method is summarized below as a typical example of a flammability test. 

An invention which provided an additive for polyethylene that produced polyethylene with self-extinguishing properties xmder an ASTM flammability test and flame-retarding properties according to an Underwriters Laboratories flame retardant test, was disclosed in U.S. Patent 2,480,298 issued to WB. Happoldt on August 30, 1948, and assigned to DuPont Company. The combination of antimony trioxide (20-35 wt%), at least... 

UL 94, developed by Underwriters Laboratories, is one of the most widely used and most frequently cited sets of flammability tests for plastic materials. These tests are for the flammability of plastic materials used for parts in devices and appliances. The results are intended to serve as a preliminary indication of the material s suitability with respect to flammability for a particular application. The UL... 

Most plastics will ignite on heating and will eontinue to bum once the source of heat is removed. The products of combustion may be toxic gases, like formaldehyde from phenolics corrosive, like hydrochloric acid from PVC or sooty, like polystyrene. Tests are available to measure the ease with which they ignite, if they continue to bum once the source of ignition is removed and the smokiness of the products of combustion. The topic of flammability is complex and there are many tests related to various plastics, plastic products and end-use scenarios. None of the laboratory scale tests are wholly acceptable, and must be backed by full scale simulated fire tests. 

Fire and Flammability Test Standards. Regardless of the application, it is important that fire and flammability test methods be free of systematic error (bias). It is also essential that consistent results can be obtained fix>m experiments repeated at different times within one laboratory (repeatability) and that there is reasonable agreement between the results for the same material, product, or assembly tested in different laboratories (reproducibility). These are the reasons why fire safety codes, regulations, and specifications refer to standardized fire and flammability test methods and why test data needed in support of fire engineering are obtained with standardized experimental protocols. 

Flammability. The results of small-scale laboratory tests of plastic foams have been recognized as not predictive of their tme behavior in other fire situations (205). Work aimed at developing tests to evaluate the performance of plastic foams in actual fire situations continues. All plastic foams are combustible, some burning more readily than others when exposed to fire. Some additives (131,135), when added in small quantities to the polymer, markedly improve the behavior of the foam in the presence of small fire sources. Plastic foams must be used properly following the manufacturers recommendations and any appHcable regulations. 

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