Extinguishment of Combustible Porous Solids by Water Droplets. Annual Progress Report.
Extinguishment of Combustible Porous Solids by Water
Droplets. Annual Progress Report.
(2195 K)
Atreya, A.
NIST GCR 93-621; Annual Progress Report; 28 p. April
1993.
Sponsor:
National Institute of Standards and Technology,
Gaithersburg, MD
Available from:
National Technical Information Service
Order number: PB93-198893
Keywords:
porous solids; extinguishment; diffusion flames; fire
extinguishing; fire suppression; flame spread; droplets;
water; infrared photography; polymethyl methacrylate
Abstract:
This report presents a brief summary of the previous
research on fire suppression with the objective to
provide guidance for the present work. Reasons for the
adopted methodology are summarized and the apparatus
developed for the study is described. Finally, some
results for PMMA are presented along with conclusions
and future work. Two experimental configurations are
chosen for this study: (1) Stagnation-point flow
apparatus: which allows studying both the gas-phase and
the condensed-phase suppression actions and enables
transient chemical measurements in the exhaust gas.
These measurements are used to study the suppression
mechanisms and quantify the suppression effectiveness.
(2) Counterflow diffusion flame apparatus: which allows
detailed flame structure measurements but is limited to
studying gas-phase suppression mechanisms (chemical
and/or physical). Initally, the work is done using the
stagnation-point flow apparatus with water as the
extinguishing agent and PMMA as the burning solid to
establish a standard for comparison of suppression
effectiveness of various agents. Our experimental
results for PMMA show that there are two simultaneous
effects as a result of water application: (1) chemical
enhancement of the burning rate (which is important only
when the flames are sooty; Note: most fires are sooty),
and (2) physical cooling of the solid via water
evaporation. The chemical effect has not been
previously noted because water is usually applied in
much greater quantities than needed and in this domain
the physical cooling effect dominates. Thus, future
work is directed toward better understanding the
suppression mechanisms.
