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ASTM E1995-2008 在单个闭室中利用带水平试样的锥形辐射源测量烟雾昏暗度的标准试验方法

ASTM E1995-2008 在单个闭室中利用带水平试样的锥形辐射源测量烟雾昏暗度的标准试验方法

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【英文标准名称】: Standard Test Method for Measurement of Smoke Obscuration Using a Conical Radiant Source in a Single Closed Chamber, With the Test Specimen Oriented Horizontally
【原文标准名称】: 在单个闭室中利用带水平试样的锥形辐射源测量烟雾昏暗度的标准试验方法
【标准号】: ASTM E1995-2008
【标准状态】: 现行
【国别】: 美国
【发布日期】: 2008
【实施或试行日期】:
【发布单位】: 美国材料与试验协会(US-ASTM)
【起草单位】: E05.21
【标准类型】: (Test Method)
【标准水平】: ()
【中文主题词】:
【英文主题词】: cone heater; fire; fire-test-response characteristic; optical density; smoke; smoke obscuration; Calibration--air/atmospheric analysis instruments; Calibration--temperature analysis instrumentation; Closed chamber testing; Conical radiant heater; Fir
【摘要】: This test method provides a means for determining the specific optical density of the smoke generated by specimens of materials, products, or assemblies under the specified exposure conditions. Values determined by this test are specific to the specimen in the form and thickness tested and are not inherent fundamental properties of the material, product, or assembly tested. This test method uses a photometric scale to measure smoke obscuration, which is similar to the optical density scale for human vision. The test method does not measure physiological aspects associated with vision. At the present time no basis exists for predicting the smoke obscuration to be generated by the specimens upon exposure to heat or flame under any fire conditions other than those specified. Moreover, as with many smoke obscuration test methods, the correlation with measurements by other test methods has not been established. The current smoke density chamber test, Test Method E 662, is used by specifiers of floor coverings and in the rail transportation industries. The measurement of smoke obscuration is important to the researcher and the product development scientist. This test method, which incorporates improvements over Test Method E 662, also will increase the usefulness of smoke obscuration measurements to the specifier and to product manufacturers. The following are improvements offered by this test method over Test Method E 662: the horizontal specimen orientation solves the problem of melting and flaming drips from vertically oriented specimens; the conical heat source provides a more uniform heat input; the heat input can be varied over a range of up to 50 kW/m2, rather than having a fixed value of 25 kW/m2; and, the (optional) load cell permits calculations to be made of mass optical density, which associates the smoke obscuration fire-test-response characteristic measured with the mass loss. Limitations : The following behavior during a test renders that test invalid: a specimen being displaced from the zone of controlled irradiance so as to touch the pilot burner or the pilot flame; extinction of the pilot flame (even for a short period of time) in the flaming mode; molten material overflowing the specimen holder; or, self-ignition in the nonflaming mode. As is usual in small-scale test methods, results obtained from this test method have proven to be affected by variations in specimen geometry, surface orientation, thickness (either overall or individual layer), mass, and composition. The results of the test apply only to the thickness of the specimen as tested. No simple mathematical formula exists to calculate the specific optical density of a specimen at a specimen thickness different from the thickness at which it was tested. The literature contains some information on a relationship between optical density and specimen thickness [1]. Results obtained from this test method are affected by variations in the position of the specimen and radiometer relative to the radiant heat source, since the relative positioning affects the radiant heat flux (see also Appendix X2). The test results have proven sensitive to excessive accumulations of residue in the chamber, which serve as additional insulators, tending to reduce normally expected condensation of the aerosol, thereby raising the measured specific optical density (see 5.5.8.3 and 11.1.2). The measurements obtained have also proven sensitive to differences in conditioning (see Section 10). Many materials, products, or assemblies, such as some carpeting, wood, plastics, or textiles, require long periods to attain equilibrium (constant weight) even in a forced-draft conditioning chamber. This sensitivity reflects the inherent natu......
【中国标准分类号】: C80
【国际标准分类号】: 13_220_40
【页数】: 24P.;A4
【正文语种】: 英语

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