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Fire Tests of Wood- and Metal-Framed Partitions.


pdf icon Fire Tests of Wood- and Metal-Framed Partitions. (6603 K)
Ingberg, S. H.; Mitchell, N. D.

BMS 71; 53 p. May 12, 1941.

Keywords:

partitions; wood; metals; fire tests; fire endurance tests; fiber insulating boards

Abstract:

This report describes in some detail the test partitions and gives the results of 147 fire-endurance or fire and hose-stream tests conducted at the National Bureau of Standards. Seventy-eight of the partitions were of wood or framed with wood studs and faced with wood, wood fiber, or gypsum boards, or with plasters applied on wood, gypsum, expanded-metal, or wire laths. The others were of hollow or solid incombustible nonbearing types, most of which were framed with steel channels and had body or facings of gypsum or portland cement plaster on metal laths. Most of the wood-study partitions were of the load-bearing type, and 38 of them were tested under a constant working load while exposed to fire. Their fire-resistance limits, depending on the facings, ranged from 10 min with 1/2-in. wood-fiber insulating boards applied on each side to 2 hr with 1-in.-thick facings of neat wood-fibered gypsum plaster. Filling the spaces between studs with mineral wool increased the fire resistance appreciably. The fire-resistance limit was considered reached when (a) failure under load or passage of flame occurred, (b) the limiting temperature rise (250 degrees F average or 325 degrees F maximum) was reached on the unexposed side, or (c) cotton waste in contact therewith became ignited. The protection given the wood studs by the fire-exposed facing, as based on the limiting temperature rise on the edges facing the furnace, ranged from one-sixth to one-third of the fire-resistance limit of the partition construction as such. The results with metal-framed hollow partitions differed little from those with wood-stud partitions having the same facings, insofar as the rise of temperature on the unexposed surface was concerned, but the former remained longer as barriers to the spread of fire after such technical end points had been reached. For the solid plaster partitions, 2 to 2 1/2 in. thick, the range in fire resistance was from 20 min with portland cement sanded plaster or mortar to 2 1/2 hr with unsanded fibered gypsum plaster. Sanded gypsum plasters gave intermediate results. For incombustible materials not subject to decided cracking or spalling when exposed to the furnace test. It was found that the fire resistance, as limited by the temperature rise on the side not exposed to fire, varied approximately with the 1.7 power of the thickness of solid partitions or combined thickness of facings for those of hollow type. This is in fair agreement with relations derived from the theory of heat conduction.