Workshop at Indian Institute of Science 9-13 August, 2010 Bangalore India Fire Safety Engineering & Structures in Fire Organisers:CS Manohar and Ananth Ramaswamy Indian Institute of Science Speakers:Jose Torero, Asif Usmani and Martin Gillie The University of Edinburgh Funding and Sponsorship: Fire Safety Engineering Methods Session JT9

Smoke Detection

Detection ♦Most obvious mechanism of early warning ♦Types of detectors: –Smoke Detectors (soot particles) –CO detectors –Temperature detectors –Multiple-inputs (artificial inteligence systems) –etc ♦We will discuss smoke detectors

Background (I) ♦For more than 40 years the fire literature has dedicated numerous studies to the understanding of “smoke” –Foster, W.W., “Attenuation of Light by Wood Smoke,” British Journal of Applied Physics, Vol. 10, pp , –Seader, J.D., and Einhorn, I.N., “Some Physical, Chemical, Toxicological, and Physiological Aspects of Fire Smokes,” 16 th Symposium (International) on Combustion, Proceedings, The Combustion Institute, pp – 1445, –Seader, J.D., and Ou, S.S., “Correlation of the Smoking Tendency of Materials,” Fire Research, Vol. 1, pp. 3-9, –Clark, F.R.S., “Assessment of Smoke Density with a Helium-Neon Laser,” Fire and Materials, Vol. 9, No. 1, pp , –Mulholland, G.W., “Smoke Production and Properties,” SFPE Handbook of Fire Protection Engineering, 2 nd ed., DiNenno, P.J., Ed., National Fire Protection Association, Quincy, MA, pp , –Dobbins, R.A., Mulholland, G.W., and Bryner, N.P., “Comparison of a Fractal Smoke Optics Model with Light Extinction Measurements,” Atmospheric Environment, Vol. 28, No. 5, pp , –Mulholland, G.W., and Croarkin, C., “Specific Extinction Coefficient of Flame Generated Smoke,” Fire and Materials, Vol. 24, pp , 2000.

Background (II) ♦For more than 20 years the fire community has tried to establish a coherent metric to assess the performance of smoke detectors. –Levine, R., “Detection and Smoke Properties,” U.S./Japan Cooperative Program on Natural Resources, Panel on Fire Research and Safety, Vol. 6, Oct , Tokyo, Japan, pp. 1 – 31, –Lee, T.G.K., and Mulholland, G. “Physical Properties of Smokes Pertinent to Smoke Detector Technology,” NBSIR , National Bureau of Standards, Gaithersburg, MD, pp.2, –Heskestad, G., “Generalized Characterization of Smoke Entry and Response for Products-of- Combustion Detectors,” Fire Protection for Life Safety Proceedings of a Symposium, March 31- April , National Academy of Sciences, Washington, D.C., pp , –Mulholland, G.W., and Liu, B.Y.H., “Response of Smoke Detectors to Monodisperse Aerosols,” Journal of Research of the National Bureau of Standards, Vol. 85, No. 3, pp. 223 – 237, –Mulholland, G.W., “How well are we measuring smoke?” Fire and Materials, Vol. 6, No. 2, pp , –Schifiliti, R.P. Meacham, B.J., and Custer, R.L.P., “Design of Detection Systems,” SFPE Handbook of Fire Protection Engineering, 2 nd ed., DiNenno, P.J., Ed., National Fire Protection Association, Quincy, MA, 1995, p –Grosshandler, W.L., “Progress Report on Fire Detection Research in the United States,” U.S./Japan Government Cooperative Program on Natural Resources (UJNR), 13 th Joint Panel Meeting, March 13 – 20, 1996, Giathersburg, MD, Vol. 2, Beall, K.A., Ed., pp , –Bukowski, R.W., and Reneke, P.A., “New Approaches to the Interpretation of Signals from Fire Sensors,” Sensors Expo, Proceedings, Baltimore, MD, Helmers Publishing, Inc., Peterborough, NH, pp , –Mulholland, G.W., Johnsson, E.L., Fernandez, M.G., and Shear, D.A., “Design and Testing of a New Smoke Concentration Meter,” Fire and Materials, Vol. 24, pp , 2000.

Background (III) ♦Multiple standards have been developed (i.e.) –Underwriters Laboratories Inc., “Standard for Safety 268: Single and Multiple Station Smoke Alarms,” 5th Ed., Underwriters Laboratories Inc., Northbrook, IL, –Underwriters Laboratories Inc., “UL Standard for Safety for Single and Multiple Station Smoke Alarms, UL 217,” 5 th Ed., Underwriters Laboratories Inc., Northbrook, IL, ♦Nevertheless, there is a common believe that no metric seems to provide a comprehensive assessment of detector performance ♦Our discussion will only deal with the principles of smoke detection

Background (IV) ♦Smoke characteristics are a function of many things: Fire size Fuel Ventilation Burning characteristics Agglomeration rates (flow conditions, acoustic fields)

Examples n-Heptane-45 cm pan Polyurethane Foam Smoldering newspaper

Background (V) From Mulholland, SFPE Handbook, 1995

Smoke Detectors IonizationPhotoelectric

Background (V) ♦Currently, light obscuration is used as the main parameter to define detector performance V + - Ionization Detectors IOIO ITIT ISIS IAIA Photoelectric Detectors Light Obscuration Measurement s I T =f(, d p, N) V=f(d p, N (strong)) I S =f(, d p (strong), N)

UL-217- “Smoke Box”

Obscuration I 0 – initial light intensity

Optical Density D e – optical density  – extinction coefficient C – particle mass concentration L - distance

Fuel

Background (VI)

Effect of Fire Size (II)

Effect of Fire Size (I) Mass Optical Density ♦Serves to scale the Optical density by the mass burning rate (i.e. Energy Release Rate) ♦Assumes that the specific extinction coefficient (  s ) and soot yield are not dependent with fuel size.

Effect of Fire Size (III)

Reference ♦Particulate Entry Lag in Spot-Type Smoke Detectors, Cleary, T. G.; Chernovsky, A.; Grosshandler, W. L.; Anderson, M. Fire Safety Science. Proceedings. Sixth (6th) International Symposium. International Association for Fire Safety Science (IAFSS). July 5-9, 1999, Poitiers, France, Intl. Assoc. for Fire Safety Science, Boston, MA, Curtat, M., Editor, pp, ♦ –Go to publications –Author –Cleary –You will find a list of his publications and a link to a pdf of the above paper