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VERTICAL VENTILATION
The modifications needed for vertical ventilation operations presented more of a change for me than those for horizontal ventilation. I was always taught to get to the roof and open the natural openings right away, burping the building. This, too, needs to be coordinated with the attack team. The study showed that when vertical ventilation was conducted, whether a skylight, scuttle, or a hole cut in the roof, if no water is being applied, the temperatures in the fire compartment spiked. The reason is that the size of the opening in the roof allows less heat to be released than the open door adds to the energy at the ground level and heat release rate. The air allowed into the fire area from the open door and other openings in the structure generates more energy than is released through the limited opening in the roof; as a result, the fire temperatures soar.
What this means is that we need to coordinate our vertical ventilation as well. This requires communication between the attack teams and the roof team and, above all, discipline. Another segment of the study showed that regarding vertical ventilation, it did not matter where you vented so long as water was being applied to the fire. The best case, of course, is to vent as directly over the fire as is safe, but there is a double-edged sword there. In the study, ventilation directly over the fire without water application, coupled with an open door at the ground level, created the worst heat conditions that could be produced and was the best way to accelerate the fire, producing the worst conditions in the shortest time.
Although these studies were conducted for fires in single-family dwellings of one and two stories, I feel this disciplined approach to coordinating ventilation can also be applied to multiple dwellings. We have been taught to get to the roof and open the bulkhead door, scuttle, or skylight on a flat-roof building. This was done regardless of whether water was on the fire or there was a closed apartment door in the stairwell. This is especially true in the case of an open apartment door. Opening at the top of the stairs with an open apartment door can pull fire into the stairwell, which is the main focus of protection. It stands to reason, based on limiting the ventilation opportunities to the fire until we have water ready, that it is best to hold off on vertical ventilation of natural openings until the door to the fire apartment has been confirmed to be closed (controlled). To reopen the apartment door, a charged line must be in place in the stairwell and ready to attack.
This is also true if a shaft fire exists. Think about a shaft fire, an open doorway at ground level, and an open doorway to the apartment. Venting over the stairs without water or compartmentation by virtue of a closed apartment door could pull fire right out of the shaft and into the apartment and stairwell, cutting off escape routes from the upper floors. In regard to timing, if you really think about it, with a vent team going to the roof and an attack team accessing the fire floor, the only time the vent team might beat the attack team to the respective operational areas is when the fire is on the top floor of a five- or six-story structure. Regardless, a little communication between the vent team on the roof and the attack team in the stairwell regarding fire conditions, water in the line, and a closed door to the fire apartment might save some unintended consequences later. “Communicate and coordinate” is always the best policy.
Case Study
In Fireground Strategies, I talk about a fire that occurred in a large multiple dwelling of ordinary construction in North Bergen, New Jersey. The fire was on the second floor and had extended to the third. There was a severe wind condition blowing from rear to front, creating all kinds of flow paths, most of them undesirable and unsympathetic to our attack plans. At that fire, I was doing recon as additional lines were being stretched to the fire area. I forced a door to one of the adjacent apartments on the floor below where the fire appeared to be. As soon as I opened the door, a large body of fire rolled around the corner of the apartment interior and headed for the door I had opened. I did not have a charged line, and it took all I had to get the door reclosed to keep the fire out of the hallway. Eventually, a line was placed and pushed the fire back, but in hindsight, it was not a smart move. There was a lot of fire in that apartment. By opening the door (with the ground-floor door open and the bulkhead at the roof open), I changed the flow path and created a more dangerous situation.
VOIDS
My department recently had another stubborn fire in a two-story, wood-frame dwelling with a moderately peaked roof (with snow on it) that started in a crawl space beneath the house. The fire had a good head start and was pushing heavy smoke from the extended porch roof above the first floor and in the floor and wall voids leading to the attic. A fire in the voids will follow its own flow path, influenced by these voids and the building’s construction until we open them up. Opening them without water ready to be applied can create some dangerous situations on the fireground. I made sure we had lines in place everywhere we were opening up, which required two lines on both the first and second floors. The building was braced frame, not balloon as we had expected from this type structure. This fire was in the pipe chases on the D side of the building, and opening up was complicated by the presence of tin ceilings and a considerable amount of occupant debris and furniture as well as renovations that created small rooms with low ceilings (more illegal renovations). We also had the ladder company on the roof ready to vent, but I did not allow them to cut right away until we definitely found fire in the walls on the second floor, as I did not want to influence the flow path into the attic until we could draw the fire out where we wanted it. For such a little building, a lot of hard work was necessary. Because of our efforts, we were able to confine the fire to the D side, partly because I feel we controlled the flow paths and did not open up without charged lines in place and ready to go (photo 4).
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| (4) Crews work at keeping this fire confined to the D side of the structure. To help accomplish this, no voids were opened without hoselines in place, and the roof was not opened until fire was showing in the flow path. It was a really cold night. |
Looking at these findings and how we must conduct our operations, I do not feel that we are drastically changing the way we do things (or are supposed to do things), for a coordinated attack has always been the only acceptable way of fighting fire from the interior (in fact, anything else is unacceptable). I also feel that although these findings were done in a laboratory and made to simulate as closely as possible actual fire conditions, the conditions created in the lab can no way effectively address all the variables that you will face out in the street in a real live uncontrolled fire. Those variables include, but are not limited to, humidity and wind conditions, voids, and their related environmental impact on the interior of the structure and windows and doors that might have been opened or broken prior to the fire department’s arrival and attack. That having been said, these studies certainly have provided enough evidence that requires us as a business to take careful notice and tighten up our operations and use discipline when timing our ventilation operations with attack.
The key to understanding these adjustments in our traditional fire attack is to understand how the modern fire environment has changed, namely the reduced time frame from ventilation to flashover. With only two minutes, as the study suggests, we don’t have a lot of time for mistakes. It is unwise to think otherwise, so heeding these findings and keeping them in mind in our fireground coordination will prevent the potential for the catastrophic results that uncoordinated and sloppy fire operations can bring.
As long as water is being applied and removing more energy from the fire than is being created, conditions will improve, and ventilation can be conducted as intended. In fact, in all cases, well-timed and properly placed ventilation operations in strict coordination with water on the fire resulted in atmospheric cooling, a reduction in the release of heat, increased visibility, and effective flow paths opposite the advancement of the charged hoseline. Further, if we treat every fire like a ventilation-limited fire until proven otherwise, we are less likely to get ourselves in trouble with flow path violation and flashover-induced ventilation. Remember that in all cases, water on the fire increases victim survivability and firefighter safety.
A last note here is in regard to victim survivability and our ability to get to the victim. In regard to the occupancy makeup of the modern home as compared to that of 40 years ago, not only has the flashover time after ventilation been rapidly reduced but so has the time for occupants to evacuate the structure once a fire has begun. In 1970, according to the National Institute of Standards and Technology, safe public evacuation time from the onset of a fire was 17 minutes. Today, with the thermoplastic environment in which we now live, that time has been reduced to three minutes! This is, I am sure, directly linked to the poisons in today’s smoke as compared to 40 years ago. I would think this also directly affects our ability to rescue anyone in the fire area when we arrive. This information suggests that it may already be too late. This is something to consider when assessing risk vs. gain.
Keep in mind, as the study stated, that for every answer found, there are many more questions to be asked. The fire environment is dynamic. When it changes, we must question; test; and, as necessary, change with it.
ANTHONY AVILLO, a 29-year veteran of the fire service, is a deputy chief in North Hudson (NJ) Regional Fire & Rescue, assigned as 1st Platoon regional tour commander. He has a BS degree in fire science from New Jersey City University. Avillo is an adjunct professor at NJCU, teaching fire science. He is also an instructor at the Monmouth County (NJ) Fire Academy. He is an FDIC instructor and a member of the FDIC advisory board and the editorial advisory board of Fire Engineering. He is the author of Fireground Strategies, 2nd edition (Fire Engineering, 2008) and Fireground Strategies Workbook Volumes I & II (Fire Engineering, 2002, 2010). He was a contributing author to Fire Engineering’s Handbook for Firefighter I and II (Fire Engineering, 2009) and is co-author of its Study Guide (Fire Engineering, 2010). Avillo was a collaborator in the Tactical Perspectives DVD series (Fire Engineering, 2011) and has had issued the DVD Forging a Culture of Safety (Fire Engineering, 2013). Avillo was the recipient of the 2012 Fire Engineering/ISFSI George D. Post Instructor of the Year Award.
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