Change for the Better? – Part 2
Written by John on September 30th, 2009
THE CHANGING FIREGROUND ENVIRONMENT
For a moment, let’s briefly consider three scenarios:
Scenario #1
The first arriving engine company to a reported structure fire finds a fire in a 2-story hotel. A quick size-up indicates a working fire in one of the apartments on the first floor has charged the apartment and first-floor hallway with heat and smoke, resulting in minimal visibility and heat conditions that are steadily increasing. Two firefighters quickly develop an attack line into the hallway. As it is 1960, the firefighters do not have the protection of SCBA and hoods. However, as they slowly and cautiously advance down the hallway toward the seat of the fire, they stay as low as possible and monitor the heat levels with their ears. Reaching the open door to the involved apartment, they stop to the side of the door and deftly direct a spray stream towards the upper portion of the apartment and quickly close the door. After a short period of time, the firefighters open the door and observe the fire has virtually been extinguished. Final extinguishment quickly follows.
Scenario #2
With the same conditions in scenario #1, the two firefighters quickly develop an attack line into the hallway. As it is 1980, the firefighters do not have the protection of hoods. However, as they cautiously advance down the hallway, their SCBA enhances their advance towards the seat of the fire while they also monitor the heat levels in the hallway environment with their ears. Approaching the open doorway to the involved apartment, the advancing firefighters notice that conditions in the hallway are rapidly deteriorating and several tongues of flame are starting to appear at the ceiling. Reaching the open doorway, the firefighters quickly direct a spray stream with a rotating movement into the involved apartment. Although the fire is knocked down, the disturbed thermal layer and expanding steam quickly envelop the firefighters, causing extreme discomfort and some steam burns.
Scenario #3
With the same conditions as in scenarios #1 & 2, the two firefighters quickly develop an attack line into the hallway. As it is 2009, the firefighters have state of the art protective clothing, including SCBA and hoods. As they cautiously advance the attack line down the hallway, their rate of deployment is enhanced by their protective equipment. However, in their desire to reach the seat of the fire in a timely manner, their protective equipment has masked the worsening conditions in the hallway. As the firefighters approach the open doorway to the involved apartment, the apartment and hallway suddenly flashover, enveloping the advancing firefighters.
Depending on your fire service seniority, do any or all of the preceding scenarios sound familiar? Interestingly, scenarios #1, 2, and 3 all share a common thread of commonalty and change with the fireground of yesterday and today. Let’s consider where we have been with the fireground of yesterday, and where we are potentially going.
Up to the mid 1960′s, firefighters generally attacked a structure fire within two basic parameters. First, building construction enhanced firefighting operations from the perspective of conventional construction (increased fireground time as compared to minimal fireground time with lightweight construction). Second, conventional materials utilized on the interior of structures were generally comprised of wood, paper, wool, and other similar materials. When these materials burned, they yielded smoke and fire gases that were slow to ignite and burn (as compared to today). Although flashover type conditions can develop when conditions are right at any fire, the number of flashovers and resultant firefighters killed or injured from this condition were low prior to 1960. This perspective could allow more leeway, time, and safety considerations to personnel engaged in interior attack operations.
During this same time period, and in the absence of SCBA and hoods, firefighters were taught to stay low, use the oxygen around the water that was being discharged from a spray nozzle, monitor the environment with the ears/back of hands, position the firefighter with a nozzle to the side of the entrance opening when applying water to the seat of a fire, and for some confined fires, use the principle of indirect firefighting. This meant directing a spray pattern at the upper portion of a room, closing the door, and allowing the expanding steam to extinguish (or partially extinguish) the fire. However, with the advent of progress, firefighters slowly began to advance more rapidly to the seat of a fire, and indirect firefighting was slowly replaced by improved attack tools and speed (after all, why did you join the fire service? Was it to become an expert in salvage and overhaul operations, or to put first water on the seat of a fire?).
During the 1970′s and early 1980′s, building construction increasingly used lightweight materials, and the use of synthetics (petro-chemical based compounds) had also increased to the point that these types of materials were common in residential and commercial type structures. Unfortunately, when these materials burned, they yielded heat, smoke, and fire gases that were significantly different from smoke and fire gases from conventional type materials. Remember that smoke and fire gases are flammable products that when heated to the correct temperature, will readily ignite. As an example, typical fire gases and smoke from synthetic materials can ignite at between 800-900 degrees, and when burned, wood products produce 7000 BTU’s, polyurethane products produce 12,000 BTU’s, and polystyrene products produce 18,000 BTU’s. Therefore, firefighters engaged in fire attack operations began to encounter environments that were capable of burning 2-3 times hotter and faster than environments prior to the 1970′s.
In addition to a changing environment, firefighters were also utilizing the benefits of improved protective equipment that allowed advancing attack personnel to withstand higher temperatures for a longer period of time, and the ability to quickly advance to the seat of a fire. Within this concept, the “old” method of indirect firefighting, positioning attack personnel away from openings that could exhaust expanding steam from attack operations, and not disrupting the thermal layer with an attack line began to be little more than a memory. Not surprisingly, the frequency of fireground flashovers and firefighter death-injuries began to increase.
