Small-scale-burning test

UN 3d small-scale-burning test (see Fig. 6.13) sawdust soaked in kerosene, not confined explosion or detonation... 

ASTM D5207 (1991). Standard practice for calibration of 20 and 125 mm test flames for small-scale burning tests on plastics materials. 

D5025-94 Standard Specification for a Laboratory Burner Used for Small-Scale Burning Tests on Plastics Materials D5045-96 Standard Test Methods for Plane-Strain Fracture Toughness and Strain Energy Release Rate of Plastic Materials... 

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. 

Test specimens for burning rate data were 1.27 x 15.24 x 0.318 cm. Descriptions of burning rate and other flammabiHty characteristics developed from small-scale laboratory testing do not reflect hazards presented by these or any other materials under actual fire conditions. 

In practice, types of burning equipment, rate of burning, temperature and thickness of the fire bed, distribution of ash-forming minerals in the coal, and viscosity of the molten ash may influence ash behavior more than do the laboratory-determined ash fusibility characteristics. The correlation of the laboratory test with the actual utilization of coal is only approximate, due to the relative homogeneity of the laboratory test sample compared to the heterogeneous mixture of ash that occurs when coal is burned. Conditions that exist during the combustion of coal are so complex that they are impossible to duplicate completely in a small-scale laboratory test. Therefore, the test should be considered only as an empirical one, and the data should be considered qualitative and should not be overinterpreted. 

This method describes a small-scale apparatus test procedure for comparing the relative rate of burning and the extent and time of burning of cellular polymeric materials. 

Preliminary small scale combustion tests carried out with the pyrolysis oil as produced (20% water content) showed that it burns readily in a furnace with a conventional pressure atomizing burner, providing the combustion box is preheated. If an air atomizing nozzle is used with a pilot flame, no pre-heating of the combustion chamber is necessary. Larger scale tests for extended periods have not yet been done, but preliminary work shows that the pyrolysis oil has potential as a substitute fuel oil. 

Laboratory experiments using rodents, or the use of gas analysis, tend to be confused by the dominant variable of fuel—air ratio as well as important effects of burning configuration, heat input, equipment design, and toxicity criteria used, ie, death vs incapacitation, time to death, lethal concentration, etc (154,155). Some comparisons of polyurethane foam combustion toxicity with and without phosphoms flame retardants show no consistent positive or negative effect. Moreover, data from small-scale tests have doubtful relevance to real fine ha2ards. 

Effects on Visible Smoke. Smoke is a main impediment to egress from a burning building. Although some examples are known where specific phosphoms flame retardants increased smoke in small-scale tests, other instances are reported where the presence of the retardant reduced smoke. The effect appears to be a complex function of burning conditions and of other ingredients in the formulation (153,156,157). In a carehil Japanese study, ammonium phosphate raised or lowered the smoke from wood depending on pyrolysis temperature (158). Where the phosphoms flame retardant functions by char enhancement, lower smoke levels are likely to be observed. 

Flammability. The fire hazard associated with plastics has always been difficult to assess and numerous tests have been devised which attempt to grade materials as regards flammability by standard small scale methods under controlled but necessarily artificial conditions. Descriptions of plastics as selfextinguishing, slow burning, fire retardant etc. have been employed to describe their behaviour under such standard test conditions, but could never be regarded as predictions of the performance of the material in real fire situations, the nature and scale of which can vary so much. 

The Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances (UL 94) has methods for determining whether a material will extinguish, or burn and propagate flame. The UL Standard for Polymeric Materials-ShortTerm Property Evaluations is a series of small-scale tests used as a basis for comparing the mechanical, electrical, thermal, and resistance-to-ignition characteristics of materials. 

Air Products, a manufacture of latex binders, has completed a comprehensive study of flame retardants for latex binder systems. This study evaluates the inherent flammability of the major polymer types used as nonwovens binders. In addition, 18 of the most common flame retardants from several classes of materials were evaluated on polyester and rayon substrates. Two of the most widely recognized and stringent small scale tests, the NFPA 701 vertical burn test and the MVSS-302 horizontal burn test, are employed to measure flame retardancy of a latex binder-flame retardant system. Quantitative results of the study indicate clear-cut choices of latex binders for flame retardant nonwoven substrates, as well as the most effective binder-flame retardant combinations available. 

During the 1970 s and early 1980 s a large number of test methods were developed to measure the toxic potency of the smoke produced from burning materials. The ones most widely used are in refs. 29-32. These tests differ in several respects the conditions under which the material is burnt, the characteristics of the air flow (i.e. static or dynamic), the type of method used to evaluate smoke toxicity (i.e. analytical or bioassay), the animal model used for bioassay tests, and the end point determined. As a consequence of all these differences the tests result in a tremendous variation of ranking for the smoke of various materials. A case in point was made in a study of the toxic potency of 14 materials by two methods [33]. It showed (Table I) that the material ranked most toxic by one of the protocols used was ranked least toxic by the other protocol Although neither of these protocols is in common use in the late 1980 s, it illustrates some of the shortcomings associated with small scale toxic potency of smoke tests. 

When samples are exposed vertically to a flame or another heat source, some materials melt and drip, and do not burn up completely. This will cause their smoke results to be artificially low [9]. Burning samples horizontally makes material performance comparisons in a small scale test more logical because the entire sample will be burnt in every case. This is very relevant when dealing with fire retarded materials which do not melt or drip, and will thus, yield similar smoke production results in the vertical and horizontal modes. 

For the specific extinction area correlation described in (a) those materials which did not burn completely in the full-scale were specifically excluded [12]. The small scale test always leads to complete consumption of the sample. Therefore, more smoke is being produced in the small scale test than in real fires for those materials usually associated with lower fire hazards. This is exactly the kind of issue that is being remedied by measurements of smoke parameter or smoke factor. 

The most important distinctions to make are between large scale and small scale tests and to clearly define which aspect of fire is being evaluated, for example ease of ignition, rate of burning, smoke production, etc. Large... 

The test method (ASTM D-720) is a small-scale test for obtaining information regarding the free-swelling properties of coal. The results may be used as an indication of the caking characteristic of the coal when burned as a fuel. This test is not recommended as a method for the determination of expansion of coals in coke ovens. 

Many tests have been devised to evaluate the fire and flame resistance of surface-treated acoustical fiberboard. The most widely accepted test, recognized by both the building industry and the building code agencies, is the fire-resistance test specified in federal specification (3). Other tests under consideration, but not universally adopted, are the tunnel test of the Underwriters Laboratories, Inc. (11), and the Factory Mutual room burn out test (2). A small scale test that is being employed for plant control and quick finish evaluation is the Class F fire test (12). 

Exposure to toxic fire effluents can lead to a combination of physiological and behavioral effects of which physical incapacitation, loss of motor coordination, disorientation are only a few. Furthermore, survivors of a fire may experience postexposure effects, complications, and burn injuries, leading to death or long-term impairment. The major effects, such as incapacitation or death, may be predicted using existing rat lethality data, as described in ISO 1334431 or more recently, based on the best available estimates of human toxicity thresholds as described in ISO 13571,5 by quantifying the fire effluents in different fire conditions in small-scale tests, using only chemical analysis, without animal exposure. 

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