Dicus, Christopher

Grant, Casey

Korman, Thomas

Lohr, Steve

Madrzykowski, Dan

Mowrer, Fred

Pascual, Chris

Turner, Dan

English

DigitalCommons@CalPoly

Compressed Air Foam and Structural Firefighting Research BY CHRISTOPHER A. DICUS, THOMAS KORMAN, CASEY GRANT, STEVE LOHR, DAN MADR:ZYKOWSKI, FRED MOWRER, CHRIS PASCUAL, AND DAN TURNER A NEW STIJDY, FUNDED BY THE DEPARTMEI\'T of Homeland Security's Assistance ro Firefighters Grants, is investigating d1e effectiveness, limitations, and potential safecy concerns of compressed air foam sys­tems (CAFS) for s tructural fuefighting. CAFS use a designated mixture of water, Class A foam , and compressed air dlat is applied through a hose and nozzle to control a fire (photo 1). CAFS were originally used for wildland firefighting in dle early 1970s and then later gained popularity for fighting structural fires because of dleir many purported benefits, which in­cluded faster knockdown time, rapid heat reduction, lowered potentiaJ for flare-ups, and reduced water use. Although used in various fire districts throughout dle world, CAFS technology and use have not evolved as fully as had been anticipated. Despite generally favorable reviews of the overall effectiveness of CAFS in extinguishing interior struc­rural fires, questions remain about dleir efficacy compared to water, which is of particular concern given that compt"essed air foam (CAF) is more expensive than water. Further, there are safe£)' concerns (based largely on Limited anecdotal evi­dence) associated with CAF, such as the potential for splash­back, which might subsequently obscure vision and increase slip hazards and h e ightened hose kinking and rupture. AJdlough some independent research by individual fire districts and organizations exists, comprehensive and peer­reviewed science is limited at present. Given the current interest in and concerns with CAP, a simultaneous, scientifi­cally sound investigation of its positive and negative aspects Table 1. 2011 CAFS \\'orkshop Participants Assistance to Firefighters Grant Program Office A-Foam Authority California Polytechnic State University CAFS Institute ;Cambria Commurrty Services District (CA) Fire Department ;tCentlal Valley (Belgrade, MT) Fire D1stnct ;Dallas Bay (TN) Volunteer Fire Department & Rescue Fire Protection Research Foundation tFort Worth (TX) Fire Department Grand Rapids (MI) Fire Department Hanover (VA) Fire & EMS tlntematJonal Assoc1atJon of Fire Ch1efs ;International Associat1on of Fire Fighters International City/County Management Association Insurance Services Office lntPmi'ltional Society of Fire Serv1ce Instructors Manchester {NH) Fire Department Los Angeles County (CA) Fire Department ;Montgomery County (MD) Fire & Rescue Montana F~re Services (MT) Training School Montreal (Quebec, Canada) Fire Department ;National Fire Protect1on Association National Institute of Standards and Technology National Research Council of Canada ;National Volunteer Fire Council tNorthwest (AZ) Fire/Rescue District Phoenix {AZ) Fire Depanment R1chmond (VA) Fire Department (1) When CAF is applied on a vertical surface, it can adhere to it for an extended time. (Photo by D. Madrzykowski.) t Member of the Project Technical Panel. www.FireEngineering.com FIRE ENGINEERING July 2013 65 e RESEARCH is needed, the results of which should be readily available to the public. To ameliorate the lack of empirical research, !his two-year study is comprehensively examining the capabilities and limitations ofCAF for interior strucrural firefighting to better understand its effectiveness and the s afety imp lications for fire service personnel. Researchers at california Po lytechnic State University-San Luis Obispo are leading this project in collaboration with the National Institute of Standards and Technology and the Fire Protection Research Foundation. Also involved are fire service partners from across the United States and Canada, with a Project Technical Panel of high -level fire service personnel experienced in CAF and the specific needs of firefighters to provide guidance to the researchers (Table 1). (2) A California Polytechnic State University fire protection engineering student conducts a test on nozzle forces that a firefighter would experience. (Photo by O.R. Turner.) (3) California Polytechnic State University fire protection engineering students conduct a test to measure hose kinking associated with CAFS. (Photo by O.R. Turner.) Table 2. Potentia l CAfS Advantages/ Disadvantages \ 'S . \X7ater-Only Systems Advantages/Claims Disadvantages/Concerns Tactical • Reduced water use • Increased nozzle reaction • Greater reach • Grciltor ~lipping hazard • Less extinguishment time • Greater hose kinking • Reduced firefighter fattgue Equipment • Greater maneuverability • Sp lashback and obscured vision • Separation of water and foam • Potential degradation of foam • Increased complexity of controls for engineer Envtronmental Training • Better surface adhesion • Better heat absorption • Reduced chance for flashover • Less property damage • Faster attack and knockdown • More efficient exposure protection • Fire investigation advantages •,Increased chance of line rupture • Reduced heat absorption • Reduced gas cooling • Greater environmental concerns • Health risks • Cold environment concerns • Cost and maintenance • Fire investigation disadvantages Topic Table 3. CAFS vs. \\later-Only Systems Tests 	 Preliminary Results Large-scale fire tests • Gascooltng • Little difference in gas cooling between CAFS and water • Knockdown time • Little difference tn knockdown/rekindlet: • Rekindle tlme Fireground evolution tests • Nozzle reaction forces • Generally htgher tn CAFS • Kinking potential 	 • CAFS kink more easily when static but are harder to kink when flowing • Stream throw and distribution • CAF has greater throw at same pressure and more compact distributton at distance • Flow separation • Time necessary for foam separation exceeds 5 minutes and is quickly restored on initiation of flow • Flooring friction • Slippage potential varies by agent and by flooring type :t: Indicates that researchers deem that lack ofdifferences may result from too small a fire event and thus have initiated subsequent tests that involve greater structure involvement. 66 J uly 2013 FIRE ENGINEERING 	 www.FireEngineering.com e RESEARCH (4) A facility used for gas-cooling ex­periments. Temperature changes were recorded during and following flow into a nonburning room connected to the burning room by an open door­way. (Photo by C.A. Dicus) (5) A knockdown/rekindle time test facility. To simulate probable firefight­ing tactics, flow was initiated down a hallway leading to a fully enveloped room (simulating attempts to cool a gas layer), halted for 15 seconds (simulating a firefighter moving down a hall), then was recommenced into the burning room. (Photo by C.A. Dicus.) This collaborative team is working on a comprehensive literarure review of previous scientific work germane to CAP use, including unpublished, in-house studies not readily available to the public. Additionally, it is con­ducting various large-scale enclosure fire tests that will investigate CAP ef­ficacy in controlling interior strucrur­al ftres compared to water. Further, scientific fireground evolution tests are underway to investigate various characteristics of CAF that influence firefighters' efficiency and safety, including the amount of force a fire­fighter experiences when nozzles are fully opened, the potential for hose kmking, and the potential for slip­ping on various flooring s urfaces. In December 2011 38 researchers, selected to provide a well-balanced representation varied in geography, experience, and support of CAP use, attended a two-day workshop at the Montgomery County (MD) Public Service Training Academy. Participants reviewed previous and ongoing CAF use and research, multiple case srudjes illustrating success stories and concerns, a hands-on CAF demonstration, and an overview of proposed experiments. In open discussions, they considered the potential advantages and disadvantages of CAP (Table 2). In general, it was agreed that all scientific tests should focus on specific aspects of CAF use that was most pertinent to firefighter safety, to keep attendees informed of research progress, and to solicit adrutional feedback as needed. A com­prehensjve report of the workshop is available at http://www. nfpa.org/assets/files/!Research%20Fouodation/RFSumrnary­CAFSWorkshop.pdf. Based o n input from the workshop, researchers subse­68 July 2013 FIRE ENGINEERJNG O quently adjusted their original test plans to better meet the needs of the fire service (Table 3). All tests adhered to the following standards, which the Project Tecfutical Panel deemed the most likely conditions under which firefighters wouJd use CAFS: • Nozzles: Fog (1~ inch and smooth bore ('A. and 1-l1. inch) • Hose: 1~ inch • Foam concentration: 0.3 percent • 	Flow: 120 gallons per minute (gpm)/6o cubic feet a min­ute (cfm) • Water/ air pressure: 100-120 pounds per square inch (ps i) Initial fireground evolution testing began in March 2011; various firefighter safety and efficiency concerns were ex­plored. For example, nozzle reaction tests (photo 2) examined how much fo rce a fuefighter would experience w hen using CAFS vs. water-only systems, which influences firefighter fatigue. Kink force testing (photo 3) evaluated differences in www.Fire Engineering-com hose kinking, which is of special concern when the hoseline goes around comers in a structure. Friction testing examined differences in slipping hazards that firefighters may experi­ence on a variety of flooring surfaces. Separation testing (horizontal and vertical) detemtined the time it takes for CAF to separate from water in a hose when no water is flowing, which could lead to an unsafe delay in foam flow o n open­ing a nozzle. Large-scale fire tests began in September 2012 at the Live Fire Training Building at the Delaware County (PA) Emer­gency Service Training Center. Researchers replicated identical conditions for each of the individual tests by fixing nozzles on mounts. Gas-cooling experiments tested how multiple agent/ nozzle combinations varied at reducing temperatures in a nonburning room connected to a burning room by an open doorway (photo 4). Knockdown experiments evaluated CAF effectiveness in extinguishing flames in a fully enveloped, confined room with limited ventilation and the time needed for any subsequent rekindle (photo 5). Some preliminary results are included inTable 3. Note that data analysis is on going and results presented here may vary after further statistical analysis. Final reports for all experi­ments will be publicly available by the e n d of 2013; articles in scientific journals will follow. Also, a comprehensive literature review to encapsulate all p revious work on CAFS is under­way; it contains experiments from the scientific literature and from in-house studies. On final completion of a ll stages of this RESEARCH e project, the researchers hope that dus will be the most com­prehensive and applicable research project ever conducted on CAF. e Asmall investment in locking FDC protection may save the structure and the firefighter/ s you send in . Enter 150 at fireeng.hotims.com 

Compressed Air Foam and Structural Firefighting Research

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Compressed Air Foam and Structural Firefighting Research

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