Suppression of Fires Exposed to an External Radiant Flux.
Suppression of Fires Exposed to an External Radiant
Flux.
(23893 K)
Donnelly, M. K.; Grosshandler, W. L.
NISTIR 6827; 29 p. December 2001.
Order number: PB2002-103179
Keywords:
fire suppression; radiant flux profile; cup burner;
cleaning agents
Abstract:
When materials are burning in the presence of a
continuous, external energy source, they are often more
difficult to extinguish and may require an increase in
suppression agent concentration to extinguish the fire.
This situation could exist for class C fires involving
electrically energized wires that cannot be
de-energized. There is a need for data to determine what
increase in extinguishing agent concentration is
necessary when the external energy source cannot be
powered off. In response to this, a Radiant Enhanced
Extinguishing Device (REED) was developed to examine the
amount of agent necessary to suppress the fire as a
function of the flux from an external energy source. The
design for the REED is based on the design of the
standard cup burner apparatus identified in the NFPA
2001 Standard on Clean Agent Fire Extinguishing Systems
(NFPA, 2000). While the cup burner is designed for use
with liquid or gaseous fuels, the REED tests solid
fuels. Five fuel materials were tested: poly methyl
methacrylate (PMMA), polypropylene, acrylonitrile
butadiene styrene (ABS), polyvinyl chloride (PVC), and
ethylene propylene diene monomer (EPDM). Nitrogen was
used as the suppression agent for all of the materials
tested. The results showed that the amount of agent
needed to suppress the fire increased as the radiant
flux on the fuel increased. In some cases, the amount of
suppressant needed reached a plateau for the flux levels
tested. For the materials evaluated, the amount of
nitrogen needed to extinguish the sample at the higher
heat fluxes was greater than the heptane cup burner
value for nitrogen. The results demonstrate the impact
extra radiant energy can have on extinguishing a fire,
and the need for data to predict how much extra agent to
use in these situations. The REED apparatus provides a
method for collecting suppression data for fire exposed
to an external flux.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899