NFPA 270-1998 Standard Test Method for Measurement of Smoke Obscuration Using a Conical Radiant Source in a Single Closed Chamber

NFPA 270-1998 Standard Test Method for Measurement of Smoke Obscuration Using a Conical Radiant Source in a Single Closed Chamber. 1-1.11 This standard does not purport to address all of the safety problems, if any, associated with its use. It shall be the responsibility of the user of this standard to establish appropri- ate safety and health practices and determine the applicability of regulatory limitations prior to use. 1-2 Definitions. For definitions of terms used in this test method, refer to the terminology contained in ASTM E 176, Terminology of Fire Standards, and ISO 3261, Fire Tests — Vocabulary. Assembly. A unit or structure composed of a combination of materials or products, or both. Composite. A combination of materials that are generally recognized as distinct entities — for example, coated or lami- nated materials. Continuous (as related to data acquisition). Conducted at data collection intervals of 5 seconds or less. Exposed Surface. That surface of the specimen subjected to the incident heat. Ignition. The initiation of combustion evidenced by glow, flame, detonation, or explosion, either sustained or transient. Mass Optical Density (MOD). The ratio of the optical den- sity of smoke and the mass loss of the test specimen, multiplied by the volume of the test chamber and divided by the length of the light path. Sample. An amount of the material, product, or assembly to be tested that is representative of the item as a whole. Smoke Obscuration. Reduction in visibility due to smoke. Specimen. The actual section of material, product, or assembly to be placed in the test apparatus. Shall. Indicates a mandatory requirement. Time to Ignition. Time between the start of the test and the presence of a flame on or over most of the specimen surface for a period of at least 4 seconds. 1-4 Significance and Use. 1-4.1* This test method shall provide a means for determin- ing the specific optical density of the smoke generated by spec- imens of materials, products, or assemblies under the specified exposure conditions. Values determined by this test shall be specific to the specimen in the form and thickness tested and shall not be inherent fundamental properties of the material, product, or assembly tested. Therefore, closely repeatable or reproducible experimental results shall not be expected from this test method when tests are conducted for a given material, product, or assembly, while introducing vari- ations in properties such as specimen...