On May 15, 2009, Chicago Fire Department (CFD) Engine 101 and Truck 41 responded to a fire alarm. Once on the scene, they encountered a two-story, ordinary construction, multi-occupancy (residential over commercial) structure with smoke showing from the second story. After forcing entry, crews...
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On May 15, 2009, Chicago Fire Department (CFD) Engine 101 and Truck 41 responded to a fire alarm. Once on the scene, they encountered a two-story, ordinary construction, multi-occupancy (residential over commercial) structure with smoke showing from the second story. After forcing entry, crews were met by heavy smoke conditions. Using their thermal imager, the crews quickly located the stairway to the residential second floor, scanned the stairwell with their thermal imager and seeing nothing out of the ordinary, proceeded up the stairs with a fully charged handline.
As the crews approached the second-floor landing, the nozzleman came upon a small fire on the carpeting of the stairs and after extinguishing it, noticed a small opening in the stairway. After he announced the hazard to the other members, they proceeded up the staircase. Just before reaching the second floor, the stairs became spongy and suddenly collapsed, sending both the Engine 101 and Truck 41 officers plummeting nearly two full floors before landing in the basement below.
True to his training, the truck officer managed to retain possession of the handline during the fall. He quickly issued a Mayday and used the handline to extinguish the fire, which was seated in the basement area where the officers fell. Meanwhile, a quick-thinking firefighter from Engine 101 placed a 10-foot folding ladder down to the officers, who both managed to escape the basement without serious injury.
Many valuable lessons can be learned from this incident. Since this column is dedicated to thermal imaging, we will focus on those lessons. In fact, it was the role the thermal imager played that caused the CFD to contact me for help.
The first lesson is simple — take the thermal imager with you. Too many times, fire companies leave the thermal imager on the apparatus thinking they will come back for it "if they need it." In this case, the CFD members took the imager with them from the time they stepped off the apparatus and it served multiple roles in the ensuing incident. Owning a thermal imager is not valuable. Using a thermal imager is valuable.
The second lesson has to do with insulators. When the companies located the stairwell to the second floor, they used the thermal imager to scan for any visible thermal signatures and seeing none, proceeded up the stairs. Why did they not see any indication of the danger that lurked below? The written report of the incident indicated carpeted stairs and photos of the incident show that the carpet was padded. These act as great insulators. This makes thermal signatures below the carpeting difficult, if not impossible to detect.
The same thing happens with bedding. A fire victim wrapped up in sheets, blankets and comforters can be difficult to detect with a thermal imager. The very fact that your bedding keeps you warm is a testament to its insulative quality and if it is good at keeping heat in, then it must be poor at letting heat out. This is why all beds should be searched by a gloved hand regardless of what the thermal imager indicates. Anything that may act as an insulator can block thermal information from reaching the thermal imager. The fire was obviously there when the firefighters scanned the stairwell, but hidden by the carpeting. The presence of heat signatures can be very telling; however, the absence of heat signatures actually tells you nothing. When navigating a building, the absence of heat signatures is not the same as an "all clear."
The third lesson has to do with thermal contrast. The firefighters report that the image they saw on the imager while scanning the stairwell was somewhat bland and poor in contrast. There are numerous potential causes for this that are far too technical to discuss in this column, but there is a way to address it. In this case, the crews were equipped with 150 gallons per minute of liquid contrast. A quick O-pattern with a straight stream will dramatically change the thermal contrast within the stairwell or anywhere else you may want to look.