Bringing Science to the Street: UL and Firefighter Safety Research

Issue 65: Bringing Science to the Street: UL and Firefighter Safety Research

By Stephen Kerber, P.E.

During the period from 2001 through 2011, 1160 firefighters died as a result of injuries sustained in the line of duty. Although the annual number of total firefighter deaths has declined in recent years, firefighter deaths that occur inside of structures are occurring at higher rates than those reported in the 1970s and 1980s, despite a decrease in the overall number of fires.¹ In addition, ongoing changes in construction methods, building materials, home designs and products used in home furnishings present new potential safety challenges under fire conditions. Ongoing research into the characteristics of modern residential fires is therefore essential to reduce safety risks and to protect the lives of firefighters and occupants alike.

UL has long been in forefront of fire safety research to support efforts that reduce the likelihood of fire-related deaths. Much of this research has been directed toward developing a better understanding of the characteristics of modern residential fires and providing members of the fire service with the information and knowledge needed to modify firefighting tactics. While firefighting will never be without risk, UL research represents a vital contribution to overall efforts to reduce risks and to save lives.

Here is a summary of some of UL’s recent and current fire safety research projects, and their implications for firefighter safety.

Structural Stability of Engineered Lumber in Fire Conditions ²
Lightweight wood trusses and engineered lumber are increasingly replacing conventional solid joist construction in roof and floor designs in residential structures. But, fire performance data on lightweight construction materials has been insufficient to assess whether the use of these materials pose an increased risk to firefighters. In collaboration with the Chicago Fire Department, Michigan State University and the International Association of Fire Chiefs, UL researchers compared the fire performance of conventional solid joist lumber with that of lightweight lumber. The study results demonstrated that, under controlled conditions, fire containment performance of an assembly supported by solid joist construction was significantly better than an assembly supported by an engineered I-joist.

Firefighter Exposure to Smoke Particulates ³
In this study, UL partnered with the Chicago Fire Department and the University of Cincinnati College of Medicine to collect data on the smoke and gas effluents to which firefighters are exposed during routine firefighting operations and from contact with contaminated personal protective equipment. The project included investigations on three fire scales: 1) fires in the Chicago metropolitan area; 2) residential room content and automobile fires; and 3) material-level fire tests. The study determined that the combustion of materials in a fire generates asphyxiants, irritants and airborne carcinogenic byproducts that can be debilitating to firefighters. These byproducts are also found in smoke during the suppression and overhaul phases of firefighting, and carcinogenic materials can be inhaled from the air or absorbed through the skin through contact with contaminated equipment.

Firefighter Safety and Photovoltaic Systems ⁴
Photovoltaic (PV) array systems used to generate solar energy pose unique electrical and fire hazards, but there has been limited data available about the risks to firefighters dealing with fires involving these systems. UL conducted testing on functional PV array fixtures to quantify the potential hazards associated with fire scenarios involving PV installations. Among other findings, this testing identified the hazards associated with the application of water to a PV array during firefighting suppression efforts, as well as effective PV array de-energizing practices. UL’s research has also provided a basis for the development of updated firefighting operational practices in dealing with energized PV arrays.

Basement Fires and the Integrity of Engineered Floor Systems ⁵
The objective of this UL study was to increase knowledge on the response of residential flooring systems to fires originating in a basement area. Today’s flooring system components and floor covering materials are designed to limit the flow of thermal energy. As a result, materials on the underside (i.e., basement side) of a floor can be on fire while exhibiting only modest temperature increases on the top side. Standard integrity assessments, such as sounding the floor, floor sag, gas temperatures on the floor above and thermal imaging, are imperfect indicators of the actual integrity of a floor over a burning fire. The study results identified a number of tactical issues for firefighters to consider when making a determination about dealing with residential basement fires.

Impact of Horizontal Ventilation ⁶
In this study, UL researchers examined fire service ventilation practices and the impact on ventilation due to changes in modern house designs. A total of 15 experiments were conducted on two houses constructed expressly for this study, in which the ventilation locations and the number of ventilation openings were altered. One of the most important findings of this study is the critical importance of coordinating increased ventilation with the application of water or another type of fire suppressant in achieving a successful firefighting outcome. The study also affirmed that the simple act of closing a door between a firefighter and a fire can provide tenable temperature and oxygen concentrations behind the closed door, increasing the chances of survival.

Impact of Vertical Ventilation (ongoing)
Building on its horizontal ventilation research, UL is also currently examining the impact of vertical ventilation (i.e., through the roof) on the growth behavior of fires in residential structures. This two-year research project will develop empirical data on multiple vertical ventilation scenarios commonly used as firefighting tactics, including the location of the hole in relation to the fire and the impact of hole size. The data will be used to define and develop firefighting ventilation practices that can reduce firefighter death and injury. The study will also examine various suppression techniques and their impact on occupant survivability, as well as alarm response associated with different smoke alarm technologies. A comprehensive technical report detailing the findings of the research is expected in early 2013.

Stephen Kerber is with Underwriters Laboratories

1. Fahy, R., LeBlanc, P. & Molis, J. "Firefighter Fatalities in the United States—2011,” National Fire Protection Association, Quincy, MA, September, 2012.
2. Izydorek, M., Zeeveld, P., Samuels, M & Smyser, J., "Report on Structural Stability of Engineered Lumber in Fire Conditions," Underwriters Laboratories, Inc., Northbrook, IL, 2008.
3. Fabian, T., et al. "Firefighter Exposure to Smoke Particulates," Underwriters Laboratories, Inc., Northbrook, IL, 2010.
4. Backstrom, R. & Dini, D. "Firefighter Safety and Photovoltaic Installations Research Project," Underwriters Laboratories, Inc., Northbrook, IL, 2011.
5. Kerber, S., et al. "Improving Fire Safety by Understanding the Fire Performance of Engineered Floor Systems and Providing the Fire Service with Information for Tactical Decision Making," Underwriters Laboratories, Inc., Northbrook, IL, 2012.
6. Kerber, S. "Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction," Underwriters Laboratories, Inc., Northbrook, IL, 2010.

4th Quarter 2012 - A Roundtable Discussion on Fire Research - William E. Koffel, P.E., FSFPE
Highlights from a roundtable, held in mid-2012, where researchers revisited the recommendations and comments made during a 1999 SFPE workshop and the "Next 25 Years Conference,” which was held in 2008. The goal? To identify how fire protection engineers can benefit from and provide benefit to fire protection research efforts. The panelists were William E. Koffel, P.E., FSFPE (session moderator); Greg Baker, Branz, New Zealand; Louis Gritzo, Ph.D., Factory Mutual, USA; Andre Marshall, Ph.D., University of Maryland, USA; Russ Thomas, Ph.D., NRC, Canada; and Ulf Wickström, Ph.D., SP Fire Technology, Sweden. READ MORE

3rd Quarter 2012 - Facing the Future: Alternative Energy and Fire Protection Engineering - Casey C. Grant, P.E., FSFPE
The increased demand for alternative energy sources and technologies is introducing new challenges for fire protection professionals, including the reevaluation of existing codes and standards. Casey Grant explores the impact that alternative energy sources—both traditional and newer forms, such as fuel cells, Smart Grid, and concentrated solar power—will have on fire protection design as engineers work to mitigate any potential hazards that incorporating these new forms of energy might present. READ MORE

2nd Quarter 2010 - Fire Protection Engineering and Sustainable Design - Simon Dent
For the fire protection engineer, integrating sustainable building design aspirations presents the challenge of needing to resolve the conflicts between architectural vision and the code expectations for fire safety. Simon Dent discusses the challenges that FPEs must overcome to support sustainable building design, suggesting that the use of performance-based design can both liberate the design team from code restraints and address the more holistic aspects of true sustainability. READ MORE