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Fame Spread Index for Wnnrl Produafc <br /> Fire Safety of Wood Products <br /> USDA, Forest Service <br /> Forest Products Laboratory <br /> One Gifford Pinchot Drive <br /> Madison,WI 53705-2398 <br /> Numerous flame-spread tests are used, but the most common one cited by building codes is <br /> ASTM E 84,the 25-foot tunnel test.This test method involves the use of a 20-inch by 25-foot <br /> specimen exposed horizontally to a furnace operating under forced draft conditions. The two <br /> results of this test are the flame spread index and smoke developed index. <br /> In the past, select grade red oak flooring was used as a standard and was given a flame spread <br /> index of 100.Today, red oak flooring still has anindex around 100 but is no longer used in the <br /> calculation of the flame spread index.The smoke developed index is still based on red oak <br /> flooring having a value of 100.The indexes are alai based on inorganic reinforced cement board <br /> having a value of zero. <br /> For regulatory purposes,interior finish materials are classified according to their flame spread. <br /> The classes are 0-25 for Class A or I,26-75 for Class B or II,and 76-200 for Class C or III. For <br /> regulatory purposes,the requirement for smoke developed index is usually 450 or less. <br /> This list of ASTM F 84 flame spread indexes and smoke developed indexes for untreated wood <br /> products was prepared from the literature.The Forest Products Laboratory(FPL)does not have <br /> an ASTM E 84 test furnace. Results from the 8-foot tunnel(ASTM E 286)of the FPL are not <br /> comparable or equivalent to ASTM E 84 test results.A list of commercial testing laboratories with <br /> the 25-foot tunnel is available from the Fire Safety of Wood Products Research Work Unit(608- <br /> 264 5669)_ <br /> The flame spread index may depend on density,thickness,chemical composition, and surface <br /> characteristics. Finishes on the wood may affect the flame spread index depending on the <br /> thickness and composition of the finish. Changes in the procedures for calculating the flame <br /> spread index have also affected the numbers. Species identification on this list are the names <br /> given in the references. Exact identification of the species may not have been possible. <br /> Fire-retardant treatments can be used to reduce the flame spread index of wood to 25 or less. <br /> Lists of the fire-retardant coatings and pressure testers are also available from the Fire Safety of <br /> Wood Products Research Work Unit. <br /> Building code officials may require building materials to be stamped with the flame spread <br /> classification of an approved testing agency. Users should consult the manufacturer as to the <br /> availability of their product with an approved stamp. <br />