1、NFPA270 Standard Test Method for Measurement of Smoke Obscuration Using a Conical Radiant Source in a Single Closed Chamber 2013 Edition NFPA, 1 Batterymarch Park, Quincy, MA 02169-7471 An International Codes and Standards Organization IMPORTANT NOTICES AND DISCLAIMERS CONCERNING NFPADOCUMENTSNOTICE
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29、Association. All Rights Reserved.NFPA270Standard Test Method forMeasurement of Smoke Obscuration Using a Conical RadiantSource in a Single Closed Chamber2013 EditionThis edition of NFPA 270, Standard Test Method for Measurement of Smoke Obscuration Using aConical Radiant Source in a Single Closed Ch
30、amber, was prepared by the Technical Committee onFire Tests. It was issued by the Standards Council on November 27, 2012, with an effective dateof December 17, 2012, and supersedes all previous editions.This edition of NFPA 270 was approved as an American National Standard on Decem-ber 17, 2012.Orig
31、in and Development of NFPA 270The first edition of this standard, in 1998, was based on the 1997 edition of NFPA 258, StandardResearch Test Method for Determining Smoke Generation of Solid Materials, with minor revisions. Origi-nally, NFPA 258 was used for research and product development. NFPA 270
32、was developed so thatit could be used within the regulatory community for enforcement purposes. This document wasdeveloped under a different title and number designation so as not to confuse the end user, andto establish and clarify the intention and limitations that are now part of the standard.The
33、 2002 edition of this standard was updated to incorporate the Manual of Style for NFPATechnical Committee Documents requirements and editorial updates.The 2008 edition of this standard contained mainly editorial revisions and revised defini-tions for consistency with other standards.The 2013 edition
34、 of this standard is a reconfirmation of the previous edition with updatesto referenced standards.2701NFPA and National Fire Protection Association are registered trademarks of the National Fire Protection Association, Quincy, Massachusetts 02169.Technical Committee on Fire TestsBarry L. Badders, Jr
35、., ChairSouthwest Research Institute, TX RTFarid Alfawakhiri, American Iron and Steel Institute,IL MJesse J. Beitel, Hughes Associates, Inc., MD SERhonda P. Byrne, QAI Laboratories, CA RTGordon H. Damant, Inter-City Testing if the pilot flame is ab-sent, the test shall be deemed to be in the “nonfla
36、ming” mode.1.3.1.4 Light Transmissions.1.3.1.4.1 The test specimens shall be exposed to nonflamingor flaming conditions within a closed chamber.1.3.1.4.2 A photometric system with a vertical light path shallbe used to measure the varying light transmission as smokeaccumulates.1.3.1.4.3 The light tra
37、nsmittance measurements shall beused to calculate the specific optical density of the smoke gen-erated during the test.1.3.1.5 Exposure.1.3.1.5.1 The specimens shall be exposed to two conditionsout of the four standard exposure conditions, to be chosen bythe test requester.1.3.1.5.2 The four standar
38、d exposure conditions shall be asfollows:(1) Flaming at an irradiance of 25 kW/m2(2) Flaming at an irradiance of 50 kW/m2(3) Nonflaming at an irradiance of 25 kW/m2(4) Nonflaming at an irradiance of 50 kW/m22704 MEASUREMENT OF SMOKE OBSCURATION USING A CONICAL RADIANT SOURCE IN A SINGLE CLOSED CHAMB
39、ER2013 Edition1.3.1.5.3 The default conditions for testing, unless specifiedotherwise, shall be those in the flaming mode.1.3.1.5.4 Exposures to other irradiances shall also be permitted.1.3.1.6* Mass Optical Density. Mass optical density shall be anoptional fire-test-response characteristic obtaine
40、d from thistest method by using a load cell that continuously monitorsthe mass of the test specimen.1.3.2 Significance and Use.1.3.2.1* Specific Optical Density.1.3.2.1.1 This test method shall provide a means for deter-mining the specific optical density of the smoke generated byspecimens of materi
41、als, products, or assemblies under thespecified exposure conditions.1.3.2.1.2 Values determined by this test method shall be spe-cific to the specimen in the form and thickness tested andshall not be inherent fundamental properties of the material,product, or assembly.1.3.2.1.3 Closely repeatable or
42、 reproducible experimental re-sults shall not be expected from this test method when testsare conducted for a given material, product, or assembly whileintroducing variations in properties such as specimen thick-ness or density.1.3.2.2* Physiological Aspects. Physiological aspects associ-ated with v
43、ision shall not be measured by this test method.1.3.2.3* Smoke Obscuration. Predicting the smoke obscura-tion to be generated by the specimens upon exposure to heator flame under any fire conditions other than those specifiedshall not be permitted.1.3.3 Limitations.1.3.3.1 Behavior. Any of the follo
44、wing behaviors during a testshall render that test invalid:(1) Self-ignition in the nonflaming mode(2) A specimen being displaced from the zone of controlled ir-radiance so as to touch the pilot burner or the pilot flame(3) Extinction of the pilot flame (even for a short period oftime) in the flamin
45、g mode(4) Molten material overflowing the specimen holder1.3.3.2* Data Evaluation. Evaluation of the data obtained, to-gether with the individual masses, shall assist in assessing thereasons for any observed variation in measurements.1.3.3.3* Sample Thickness. The results of the test shall applyonly
46、 to the thickness of the sample being tested.1.3.3.4* Sensitivity. Sensitivity to variations shall require thatwhen changing to another sample to be tested, it shall first benecessary to clean and remove from the walls all accumulatedresidues to ensure that chemical or physical recombinationwith the
47、 effluents or residues produced as a result of the ther-mal irradiance does not affect the data obtained.1.3.3.5* Test Conditions. Specimens shall be subjected to oneor more specific sets of laboratory test conditions.1.3.3.5.1 The results shall be valid only for the fire-test-exposure conditions de
48、scribed in this test.1.3.3.5.2 This test method shall not be used to predictchanges in the fire-test-response characteristics where differ-ent test conditions are substituted or end-use conditions arechanged.1.3.3.6* Optical Density. Information relating the specific op-tical density measurement obt
49、ained by this test method to themass lost by the specimen during the test shall be obtainedonly by using the (optional) load cell to determine the massoptical density.1.3.3.7* Dynamic Measurements. This test method shall notuse dynamic measurements.1.3.3.8 Smoke Obscuration. Therefore, the smoke obscura-tion values obtained shall not represent conditions of openfires.1.4 Units and Formulas. The values stated in SI units shall beconsidered the required values of this standard.Chapter 2 Referenced Publications2.1 General. The documents or portions thereof listed in thischa
