Date: November 21, 2013
Ten Reasons Why You Should Use CAFS
While compressed-air foam systems have their roots in wildland fire operations, the technology has proved to be a revolutionary breakthrough in structural firefighting. What follows is a thumbnail sketch of the advantages found in deploying CAFS for the structure fire attack.
Improved initial-attack capability. Using CAFS, the fire-stopping effectiveness of first-arriving fire scene resources — equipment, personnel and water supply — increases up to five times. In some fire situations, this allows crews to turn a defensive operation into an offensive attack. The use of CAFS has reinvented the limits of what a given total water supply and/or water delivery rate can do. Rather then protecting exposures and letting a fire burn unhindered, CAFS often is successful in darkening the main body of a large fire.
Reduced fire-scene cycle time. Fire-scene cycle time (when the apparatus arrives on scene at a working fire to when the units return, available for the next fire) is more than an important statistic. For personnel who directly engage in fire combat, exposure to heat and toxic products of combustion is reduced, thereby lessening stress and risk of injury.
Reduced time that tankers/tenders operate on roadways. Since much less total water supply is required to extinguish a fire when applying compressed-air foam, tankers/tenders shuttling water from static supply sources in rural areas to the fire scene spend less time on the road. This reduces the risk of roadway apparatus accidents and injuries.
Reduced water use. Applying compressed air foam, the total water supply (total gallons) required to extinguish a fire is reduced to as little as one-third compared with applying water alone. This also carries through to exposure protection. Compressed-air foam clings well to vertical fire exposures, which means less water is wasted from runoff during exposure-protection operations. In rural areas where water supplies are scarce, if exposure-protection applications are needed, more water remains available for offensive fire attack.
Increased reach equals increased safety. CAF streams have greater reach than water or nozzle-aspirated foam fire streams. This provides greater standoff distances from fire hazards and greater stream penetration into structures, which translates into increased crew safety. In addition, hose lines filled with compressed-air foam are filled with about 30% air by volume. This makes them lighter and easier to advance through a structure during an interior attack, reducing stress on the attack team.
Less chance of “fire at your back.” During aggressive interior attacks of pre-flashover fires, applying compressed-air foam absorbs more heat than water, lessening the chance of potentially deadly fire compartment flashover. As attack teams advance through dwelling interiors and move past rooms where flames have been knocked-down, the wetting and penetrating action of a foam blanket applied on room furnishings reduces the chance of a rekindle and “fire at their backs.”
Superior moisture penetration equals less overhaul. During interior structure fire attack, compressed-air-foam streams cling well to horizontal and vertical room furnishings. Moisture draining from the foam blanket starts to penetrate deep-seated fire and hot spots. This results in less “dig and pull” overhaul of an interior fuel load.
Reduced smoke and steam. During aggressive interior structure fire attacks, the application of compressed-air foam preserves the thermal balance and leaves minimal smoke and steam in the atmosphere. Interior visibility is excellent and the attack team never loses sight inside the room. Firefighters are not driven to the floor by the moisture cloud penetrating their turnout gear, which they typically experience during conventional water application through a fog nozzle.
Effective structure protection. When severe wildland fires burn into populated areas, firefighters using CAFS can pre-treat the exterior of homes with a foam blanket prior to the arrival of the approaching fire. Applied on buildings with wood exteriors, the foam application raises the fuel’s moisture content. An effective exposure-protection and fire-prevention tactic, this allows time for the fire crew to egress from the area. This takes firefighters out of harm’s way before exposure to the flames and smoke normally found when using a conventional “defend-in-place” tactic.
Visible application reduces waste. During wildland/urban-interface fire incidents, the application of compressed-air foam on trees, brush, and building exposures is highly visible. This prevents over-application of agent and water wastage. The foam blanket acts as a short-term thermal barrier. Once the foam blanket evaporates, the need for reapplication is evident to fire crews.
Saving Lives and Property
Compressed-air foam is another useful tool in the toolbox to increase firefighter safety and reduce property damage. Consider the following issues.
Firefighter fatality rates, when compared to the number of fires, have remained virtually unchanged over time, even with the advent of better PPE, SCBA and PASS, as well as new consensus standards such as NFPA 1500, Fire Department Occupational Health and Safety.
Today, fewer firefighters are protecting a much larger population and more residential properties compared with 20 years ago. Despite the economic downturn, properties today still are worth more than they were two decades ago, and new homes have higher average square footage than older models. Moreover, the contents of these new larger homes pose more challenges. According to NFPA 921, Guide to Fire and Explosive Investigations, an old cotton-padded upholstered chair will produce a heat-release rate of 290 to 370 kilowatts (kW), while a newer polyurethane chair will produce a heat-release rate of 1,350 to 1,990 kW. Current construction techniques (e.g., wood-truss roof assemblies) make new homes more hazardous due to their poor resistance to fire and vulnerability to early structural collapse.
According to NFPA, there has been a decrease in the incidence of structure fire over the past four decades throughout the U.S. As a result, firefighters today have less experience than their predecessors had a generation ago. As experienced firefighters and officers retire, they are replaced by young officers with less experience. These young officers may be unable to recognize and react quickly to flashover and building collapse, which could result in injuries and fatalities.
While building codes and construction standards have risen to higher levels in some parts of the country, the adoption and installation of residential fire sprinklers for new homes, and the retrofit of existing dwellings, has been a slow mover. Residential sprinklers have been proved to increase occupant fire survivability and reduce the possibility of flashover and extension of a single room fire beyond the compartment of origin. In many cases, the sprinkler system extinguishes the fire before the fire department arrives. Too little attention has been placed on the benefits that residential sprinkler technology has to offer. While not a “cure-all” for fire protection, residential sprinklers, if widely implemented, could reduce property damage and firefighter injury and fatality.
CAFS used with Class A foam will deliver large quantities of agent with existing manpower to attack structural fires that previously required massive tactical operations. The technology associated with CAFS and Class A foam is new and different to most of the structural fire service, and history tells us that the fire service will be slow to adopt it.
The first step in evaluating whether CAFS and Class A foam are the right tools for your department is to obtain training and education. Classroom instruction, followed by hands-on demonstrations, is the key to learning the advantages and limitations of what this technology can do. The importance of obtaining qualified instruction cannot be overemphasized.