Fire Tests of Wood- and Metal-Framed Partitions.
Fire Tests of Wood- and Metal-Framed Partitions.
(6603 K)
Ingberg, S. H.; Mitchell, N. D.
BMS 071; 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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899