Assessment of the Fire Performance of School Bus Interior Components. Final Report.
Assessment of the Fire Performance of School Bus
Interior Components. Final Report.
Braun, E.; Davis, S.; Klote, J. H.; Levin, B. C.; Paabo,
NISTIR 4347; 177 p. July 1990.
Sponsor:Department of Transportation, Washington, DC
Available from: National Technical Information Service
Order number: PB90-265307
buses; cone calorimeters; seats; flame spread; furniture
calorimeters; combustion products; smoke; tenability
limits; toxicity; large scale fire tests; small scale
Since seat assemblies represent the single largest type
of combustible fuel in a school bus interior, this study
is limited to currently used and state-of-the-art
material assemblies. Six different seat assemblies
having a range of fire performance were examined.
Small-scale tests (Cone Caloimeter, LIFT, and NBS
Toxicity Protocol) were performed on these materials.
Large-scale tests (Furniture Calorimeter) were conducted
on single seat assemblies. Full-scale tests were
performed using a simulated bus enclosure measuring 2.44
m wide by 2.13 m high by 8.23 m long and three seat
assemblies. The impact of ignition source size was
determined by computer simulation. It was found that a
500 kW ignition source could produce untenable thermal
conditions in the simulated bus enclosure. Seat
assemblies were exposed to 50 kw and 100 kw ignition
sources in the large-scale tests and 100 kW ignition
source in the full-scale tests. It was found that the
small-scale tests were unable to provide a simple method
for material selection that was consistent with the
full-scale test results. At the present time,
small-scale fire tests of materials cannot be depended
upon to predict the fire behavior in the real world.
Therefore, based on the full-scale test results, a
generalized full-scale test protocol for seat assembly
evaluation was developed that combines full-scale
testing in an enclosure with an analysis protocol that
determines the time-to-untenable conditions. The
procedure defines the conditions under which toxicity
testing would be necessary. Full-scale test
instrumentation and material orientation are also