Fire research abstracts and reviews: Volume 14, 1972 (1972)

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ABSTRACTS AND R E V I E W S 233 Holmes, C . A. (Forest Service Products, USDA, Madison, Wisconsin) "Methods of Evaluating Fire-Retardant Treatments for Wood Shingles," Forest Products Journal 32 y 45 (1972) Sections: A, H Subjects: Fire retardance. Shingles, Wood, Test methods, Weathering, Fu-e per- formance, Schlyter test, Burmng brand test (Class C ) , Tunnel furnace test Author's Abstract Fire-retardant treatments for western redcedar shmgles were evaluated for fire performance and leach resistance The evaluation methods for fire performance included the use of the 8-foot tunnel furnace, the modified Schlyter test, and a modified Class C burning brand test Leach resistance of the treatments were deterimned by accelerated outdoor exposure and by severe leaching and ultra- violet exposure in a weathering apparatus The evaluation methods were shown to be adequately severe by comparing results obtained with Underwriters' Labora- tones Class C-labeled slungles as a reference Four impregnation treatment systems showed most promise of fire-retardant effectiveness and durabihty

T A B L E I Results of fire tests on western redcedar shingles after 1,000 hours' accelerated weathering Results of burning brand tests Results of Schlyter tests Chemical Coating Burning Chemical Coating Type Average Codt ! Treating process retention - brands retention - of flame No (dry) Spread D r y (failures/ (dry) Spread D r y test spread rate' weight' applied) rate' weight* P c f P c f I n Factory treated 36 Factory treated, U L Class C labeled —> 0 0 0/8 —' 0 0 Mild 2 do —> 0 0 0/8 0 0 Severe 13 Untreated controls 1 Untreated 0 0 0 7/7 0 0 0 Mild 38 do 0 0 0 7/7 0 0 0 Severe 46 Fire-retardant coatmgs 1,1 Coating of F - R epoxy paint 0 90 36 3 0/8 0 133 24 8 Mild 4 do 0 132 21 2 0/8 0 133 26 4 Severe 36 Vacuum-pressure impregnations 18 Impiegiiated, sodium tetraborate- monoammonium phosphate 6 4 0 0 4/8 6 4 0 0 Mild 16 do 6 4 0 0 8/8 6 4 0 0 do 15 22 Impregnated, double-salt sodium tetraborate and zmc chloride' 7 0 0 0 7/8 7 0 0 0 do do 7 0 0 0 6/7 7 0 0 0 Severe '15 Vacuum-pressure impregnations with sealer coatmgs 23 Impregnated, sodium tetraborate- monoammonium phosphate, coat- ing of preservative sealer 5 9 31 15 0 7/8 5 9 34 13 7 Mild '15 do 5 9 32 14 5 8/8 5 9 33 14 4 do «10 i I n

24 Impregnated, A W P A type D , coating of nreservafcive .seal(>r with tri- cresyl phosphate 6 3 42 25 0 0/7 6 3 41 25 9 do 3 do 6 3 41 26 0 0/6 6 3 41 25 6 Severe 23 Vacuum-pressure impregnations and additional reactions 25 Impregnated, A P O 6 3 0 0 0/6 6 3 0 0 Mi ld 3 do 6 3 0 0 0/7 6 3 0 0 Severe 14 26 do 3 8 0 0 0/8 3 8 0 0 Mi ld 3 do 3 8 0 0 0/8 3 8 0 0 Severe 20 28 Impregnated, T H P C 2 7 0 0 1/8 2 7 0 0 Mi ld 27 do 2 7 0 0 1/7 2 7 0 0 do 27 20 do 4 8 0 0 0 8 4 8 0 0 do 20 do 4 8 0 0 0/8 4 8 0 0 do 15 31 Impiegnated, dicyandiamide- phosphoric acid-foi maldehj de 5 0 0 0 3 /8 5 0 0 0 do i do 5 0 0 0 3 /8 3 0 0 0 Severe 26 ^2 do 8 3 0 0 2 /8 8 3 0 0 Mi ld 3 do 8 3 0 0 1/8 8 3 0 0 Severe 16 33 Impiegnated, dicyandiamide- phosphoric acid 7 3 0 0 2 /8 7 3 0 0 Mi ld 4 do 7 3 0 0 0/8 7 3 0 0 Severe 25 34 do 9 3 0 0 1/8 9 3 0 0 Mi ld 4 do 9 3 0 0 1/7 9 3 0 0 Severe 20 35 Impregnated, zinc sulfate-zinc sihcofluoride-urea 12 9 0 0 5/6 12 9 0 0 Mi ld 7 do 12 9 0 0 4/7 12 9 0 0 Severe 32 ' I n square feet per gallon of coating ' Grams of dry coating per square foot of surface ' D r y chemical retention not known * D r y chemical retentions are calculated as zinc borate ' Panels had a light glow on butt edges for about 11 min ' Heavy afterglowmg Extinguished with water after 10 mm ' Afterglow along several of the butt edges Extinguished with water after 27 min Glowing may have continued until the plywood backing ignited « Afterglow along butt edge at one place Self-extinguished at 24 7 min I I a to a to CO