With the debate regarding the benefits of exterior streams and ventilation control having been settled in favor of at least adopting the option to perform these potentially faster, safer, and more effective approaches for controlling fires in structures, many fire service leaders and instructors are asking: “How can our department implement these valuable practices?” Fortunately, the most significant efforts toward making these changes have already been expended by the LODD investigators whose analyses uncovered repeated examples of gaps in our understanding of fire dynamics, and the resulting flaws in our approaches; researchers who took this new knowledge of fire behavior and painstakingly documented the effects of various tactics, both conventional and non-conventional, thereby providing detailed information regarding their performances in a multitude of settings; and innovative fire departments that have integrated these “new” practices into their operations, proving their value as they hone their execution. The rest of us need only to do a little study and practice in order to reap the benefits of these tactical enlightenments.
(This post is a follow-up to “Half Ready – Limiting our options”, available at: https://community.fireengineering.com/profiles/blog/show?xg_source=…)
In general, the Modern Fire Attack (MFA) tactics that I think should be added to our standard menu involve applying water as early as possible, from whatever direction is most expedient; and limiting air flow as long as possible, using passive (don’t open) or active (close what’s already open) means. They are actually easy to perform, mostly require no special equipment, and can be implemented after just a little education and practice. The most important ingredient required for the successful utilization of these new “tools”, though, is leadership. Giving permission, direction, and, sometimes, even a command to include these measures are the first steps in ensuring their adoption. With the minimum investments of a brief update on fire dynamics and water application methods, some tweaking of department SOP/SOGs regarding standard assignments, and maybe the purchase of a smoke curtain or two, your crews will be that much more versatile and effective.
Once the option to use external streams is on the table, which is probably the most difficult step in implementing MFA tactics, the practical training involves proper nozzle technique. This includes ensuring the stream is straight or solid, positioning the nozzle as close as possible to the building so that flow can be directed upward into the window to strike the ceiling, and avoiding rapid nozzle movement (Solid/Straight, Steep, Still – SSS). This is an exceedingly easy, but unnatural, maneuver, requiring instruction and practice, however brief, to master. One of the common mistakes when operating an external stream is to move it about the target, a logical action to maximize coverage that, unfortunately, also serves to block the outflow of products of combustion/extinguishment, as even a straight/solid stream entrains a large amount of air. Keeping the nozzle relatively immobile will still cool most of the hottest gases and surfaces on the ceiling of the target room, and any movement to cover more surfaces should be slow and steady, instead of rapid and “whipping”.
Integrating this new tactic into a department’s standard operations is more complex, though, as it would be with any new tool or process. Such variabilities as crew size, apparatus configuration, and local building patterns must be factored into the various evolutions that will most efficiently place a nozzle at the appropriate spot(s). Optimizing the benefits of external streams requires minimizing the time for their deployment as well as that of still-necessary interior streams. The ideal approach at a fire that is most quickly accessible from the outside is to assign the first available crew to start water from the exterior, and the next crew to stretch the interior hoseline. Of course, this assumes sufficient personnel for near simultaneous actions. When staffing is more limited, effective evolutions might include having one firefighter first stretch and operate an exterior line, and the next firefighter stretch another hoseline to the entry point (usually a door), with both joining and advancing the interior line after the external line has been flowed to provide fire knockdown; having the MPO (aka “driver”) stretch and flow the exterior line while the remaining firefighters preparing for entry with a second line; or stretching only one line, and repositioning it from the exterior portal to the interior entryway. Realistically, though, once the decision is made to include exterior streams to the options for water flow directions, each department’s officers and firefighters are the “in-house experts” who can then determine how best to implement this tactic in their “shop”.
In circumstances where exterior hose streams are not feasible, extending the “applying water as early as possible” mantra to interior operations leads to the practice of gas cooling, which can be considered the now-acceptable act of “putting water on smoke”, and which requires even less in the way of hands-on training, but maybe more education and encouragement. The key concept that must be grasped is that the combustible gases that might be passing overhead as we stretch hoselines toward a burning compartment can exceed their ignition temperature, and remain non-burning only because they are also oxygen deficient. Delaying water application until the seat of the fire can be reached and cools bets against the often-unplanned occurrence of sudden window failure, or an inopportune breeze, that might suddenly reverse the smoke’s over-rich concentration and allow the ignition of that fuel, producing even higher temperatures over interior crews. That assumes, of course, that the smoke is not already so hot, and/or the distance to the seat of the fire not so far, that the interior crew’s PPE will provide sufficient protection. Instead of these unnecessary gambles, immediately initiating cooling of that same smoke will often not only reduce its temperature enough to allow firefighters to make their way to the ultimate target, but also prevent it from igniting overhead while en route.
The actual technique of gas cooling can be rather detailed and nuanced, ranging from simply flowing water into the overhead smoke and observing the effect, to the use of specialty fog nozzles that can produce brief bursts if ultra-fine droplets to cool and contract the smoke as crews advance. In between in complexity are such nozzle maneuvers as “shutdown and move”, where water is flowed for a period of time, the line is shut down and advanced, and then water is flowed again, repeating this sequence until the seat of the fire can be reached with the hose stream; and “flow and move”, which describes continuously flowing water in the direction of the fire as the line is advanced. (It should be noted that the latest UL research debunked the previously suggested practice of spraying water overhead and watching for the return of water, or not, to the floor, determining it to be an inaccurate gauge of overhead temperatures, as even very hot gases might not vaporize all of the water inserted.) Each of the nozzle evolutions has their advantages and disadvantages, with all but the high velocity fog technique easily accomplished with hose, nozzles, and pressures commonly utilized by the North American fire service, and I would direct those who are searching for their ideal method to review the research (https://ulfirefightersafety.org/docs/DHS2013_Part_III_Full_Scale.pdf) and some expert discussion of this topic (http://www.cfbt-be.com/images/artikelen/artikel_14_ENG.pdf).
Limiting the air flow to and from a burning compartment is complementary to rapid water capability, effectively controlling the rate of combustion until extinguishment can begin. Again, leadership and education are the primary ingredients for developing this proficiency. This requires not only acquiring an awareness of the significant increase in heat production that follows the increase of ventilation to a fire, and the opposite effect when air flow is decreased, but also acting on that knowledge. In particular, this involves suppression of the long-taught imperative to accomplish ventilation quickly, a reversal of priorities that can be difficult to implement. (Indeed, if the volume of responses to my posts on ventilation-related topics is any gauge, this may be the most controversial recommendation, and it is being opposed by a tenacious constituency who still ascribes to the “early and often” school of tactical ventilation.) Delaying ventilation until after the fire is no longer ventilation limited – essentially, after the burning contents have been cooled sufficiently that free burning ceases – ultimately results in the performance of all of the same tasks that firefighters have been doing for generations, only with adjustments to their timing relative to other tasks, specifically water application.
Besides not performing horizontal or vertical ventilation maneuvers before sufficient cooling has been accomplished, the actual techniques for minimizing ventilation include door control, so that merely entering the building does not result in worsening of conditions before water flow can begin; and halting air flow that is already occurring to and from the fire. The first uses a readily available resource – the entry door – but in a manner that had not previously been considered as important. A fire in a structure that has progressed beyond the incipient stage is likely to be ventilation limited, so that, when an initial attack is via the interior, the very act of initiating entry can increase its intensity by creating a new flow path. Opening the door only after hoselines are charged and crews are ready, and then closing it as much as possible after entry, will delay and or limit the worsening of conditions. The early initiation of water flow, as discussed above, will further blunt the ill effects of any increased air flow from the entryway.
Decreasing the amount of ventilation that is already present upon the arrival of firefighters requires more in the way of preparation and special equipment. While removing interior doors from unaffected rooms/apartments to cover those that have burnt through in order to slow a fire’s progress is a proven Truck technique, finding an appropriate replacement for an exterior door that has failed, much less a window, had not previously been considered necessary or even feasible. Smoke curtains, made of fire-resistant fabric and fitted with integrated, adjustable hangers, are now available, and can be quickly placed over failed windows or open doorways, and even within corridors, to limit the inflow of air and outflow of smoke and heat. (Tempest Technology’s PathMaster is one brand, and I have seen the smaller version – capable of covering an opening from 28 to 46 inches wide – listed by various vendors at a cost of anywhere from $539.99 to $842.95.) When used to block doors, they still allow for unobstructed passage of crews and hoselines, and can also be used within a structure to further compartmentalize a fire and limit the spread of products of combustion.
The practices of applying water from whatever route and direction can be most quickly initiated, and delaying ventilation until after this has been accomplished, are the twin capabilities that modern firefighters must have in their tactical “toolbox”. As with any new methods, once taught, practiced, and applied to different settings, variations and enhancements will naturally evolve as crews develop comfort and experience. Leadership and training are necessary for initiating these tactical enhancements, but permission and encouragement are probably the more important ingredients for starting this evolution.
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