Reduced Risk of Fire Spread

Objective:

To develop a suite of effective strategies for cost-effectively reducing the nation’s fire losses (both human and financial) based on approaches for limiting fire growth and spread. The strategies will focus on: materials flammability (new fire and material behavior models, innovative flame retardant approaches for foams and fabrics, multi-scale foam flammability tests), fire detection and suppression (economic residential sprinkler model, fire extinguisher metrics), and methods for the evaluation of hydrogen flammability hazards. These efforts contribute directly to the BFRL Goal of Innovative Fire Protection Technologies.

Problem:

What is the problem and why is it hard? Despite progress, fire losses in terms of human lives, injuries, and property damage in the United States remain high in comparison to other industrialized countries. Statistics from 2004 indicate that there were 3900 fire deaths, 17 785 fire injuries, and $12 billion in direct fire losses in the US. The actual financial cost of fire to the US economy is many times higher than the direct losses due to such associated costs as fire protection, fire insurance, fire departments, and business interruption. When these costs are considered the total is over $40 billion.

The majority of fire losses result from fires in residences, which means that a significant reduction in losses for this category offers the greatest opportunity for a significant reduction in the total cost of fire. Over the last few decades most of the residential fire losses in the US occurred in single- or two-family housing during isolated fire incidents. Analysis of fire statistics suggests that a majority of these fire death and property losses are associated with the occurrence of flashover. Flashover is the dramatic and sudden transition from a relatively small, slowly developing fire spreading systematically across adjacent fuel surfaces within a room to a much larger and dangerous fire in which all flammable surfaces within the enclosure are involved. Flashover is generally accompanied by a significant increase in the heat release rate, extension of flames out of open doors and windows (with a corresponding increase in the likelihood of fire spread to adjacent rooms), and a dramatic increase in the production of toxic fire products. Clearly, reducing the risk of flashover in isolated residential fires provides an opportunity to significantly reduce the high human and property costs of fire to the Nation.

Means exist today to prevent flashover; e.g., by installing sprinklers or by limiting the contents of the room. The problem is that these means of prevention lack general public acceptance for various reasons. As examples, installation of sprinklers in 100 % of US residences is estimated to cost about $35 M for each life saved; specialty fabrics used to limit flammability come at a premium price and may have less desirable physical properties, degrade with age, or raise environmental concerns; and false alarms outnumber fires by over an order of magnitude, rendering impractical attempts to tie alarms directly to the fire department. Models for fire growth on realistic objects do not yet exist, and standard test methods are generally not applicable to new technologies such as those associated with wide spread use of hydrogen fuels in residential and commercial settings. The lack of effective fire spread and growth models is recognized as a major obstacle to the implementation of performance-based codes.

Approach:

What is the new technical idea and why can we succeed now? Reducing the risk of flashover can be equated with reducing fire spread, fire growth, and the maximum value of the heat release rate. There are two general approaches for accomplishing these goals. The first is to limit the availability of fuel (e.g., though the use of non-combustible or fire-retarded materials) such that a fire cannot become sufficiently intense to induce flashover. The second is to provide physical intervention (e.g., through automatic suppression systems, or by a fire brigade following early detection) to reduce the fire size before it can grow to a dangerous level. The innovative applications of all of these fire protection technologies (fire retardant materials, fire detection, and fire suppression systems) are important and are included in this program.

A major impediment to efforts to reduce the risk of flashover is our insufficient understanding of fire growth and spread on room contents. Such an understanding is required for predicting the effectiveness of improving the flammability behaviors of materials in reducing the risk of flashover and for providing tools to develop more fire safe products based on an understanding of these behaviors. The unavailability of appropriate fire growth and spread models is also recognized as a serious roadblock to the implementation of performance-based fire codes. Several projects are addressing aspects of fire growth and spread on solid fuels. Related work on solid fuel response is on-going in the Advanced Measurements and Predictive Methods Program.

Recent Results:

Detection

• A series of experiments
  designed to characterize fire signatures were completed at the FM Global fire
  research laboratory as part of a joint effort withFM Global Research.


• Cleary, T.G, and Davis W., “The Response
  of Residential Smoke Alarms at Low Flow Velocities,” Proceedings of the 2006
  Fire Suppression & Detection Research Symposium, Orlando, FL, 25-27 January,
  2006.

Suppression

• 
  

  D. Madrzykowski, A. Hamins, S. Mehta, Residential Fire Suppression
  Research Needs: Workshop Proceedings, NIST SP 1066, 2007



• 
  

  W. Grosshandler, editor, "The Use of Portable Fire Extinguishers
  in Nightclubs:  Workshop Summary," NIST IR 7419, December, 2006.

  
  

 Polymer Flammability

• 
  

  J. W. Gilman,
  “Flame Retardant Mechanism of Polymer-Clay Nanocomposites” in Flame Retardant
  Polymer Nanocomposites, eds.: A. B. Morgan, C. A. Wilkie, Wiley, Hoboken,
  NJ, 2007.



• 
  

  Added 2 new members to the Fire Retardant Foam Consortium
  (Dow, Sasol, Barrier Dynamics, Bayer Material Science, Southern Clay Products,
  Foamex, Multina, Boeing).



• 
  

  T. Kashiwagi "Progress in Flammability Studies of Nanocomposites
  with New Types of Nanoparticles" in Flame Retardant Polymer Nanocomposits,
  edited by Morgan, AB and Wilkie, CA, Wiley-Interscience, Chapter 10, 2007.

  
  


• 
  

  Kashiwagi T,  Fagan J, Douglas J,
  Yamamoto K, Heckert
  AH,  Leigh SD, Obrzut J,  Du F, Lin-Gibson S, Mu M, Winey KI, Haggenmueller R,
  "Relationship Between Dispersion Metric and Properties of PMMA/SWNT
  Nanocomposites" submitted to Polymer.

Fire Spread and Growth Modeling

• K. Butler and T. Ohlemiller, "Some Difficult Problems in the
  Modeling of Fire Spread,"  presentation to the Seventh World Congress on
  Computational Mechanics, Los Angeles, Calif., July 2006


• 
  

  K. Butler, E. Onate, and R. Rossi, "Modeling Polymer Melt Flow
  Using the Particle Finite Element Method," accepted for
  presentation/publication, Interflam 2007, London, England, September, 2007

  
  


• 
  

  
  Prasad, K., "A Multi-block Technique for Simulating Fires in
  Complex Geometries, Proceedings of the Combustion Institute, 5th U.S. National
  Combustion Meeting, March 25-28, 2007, San Diego, CA.

Related Projects

- Sprinkler Decision Tool for Communities

- Performance Metrics for Portable Fire Extinguishers in Fast Growing Nightclub Fires

- Fire Growth and Spread on Real Objects

- Development of software based on AMR technique for simulating fire growth and spread.

- Nanoadditive Flame Retardants for Polyurethane Foam

- Modeling Melt Flow using Particle Methods

- High performance barrier materials for mattresses and furniture

- Modeling the Dispersion and Agglomeration of Carbon Nanotubes in Polymers

- Fire Retarded Polyurethane Foam Flammability

- Hydrogen Flammability, Detection, and Fire Safety

- Smoke Alarm Performance Standards