Responding to fires in different types of occupancies allows you to encounter many different types of hazards. Fires in commercial buildings, called taxpayers in NYC, always present different challenges for a variety of reasons.
Due to burglaries and vandalism, roll down security gates are the norm rather than the exception. Many different types of locks and security devices will also be encountered. Once you’ve overcome these, horizontal ventilation is needed to allow the engine to move in and extinguish the fire.
But, after either working your way through a series of locks or gaining forcible entry through roll down gates, one final challenge could delay your ventilation — Lexan windows.
What is Lexan? It is a polycarbonate glazing manufactured by the General Electric Corporation. It is used as a replacement for glass where the need for strength is needed, such as security for a commercial occupancy. It is also used in a variety of other places such as racing car windshields, guitar picks and Apple products such as the iPod and the computer iBook . In NYC subway cars, all windows are made of Lexan to prevent vandalism.
First encounter
My first encounter with Lexan was many years ago at a commercial fire in a one story 75' x 100' appliance store. After using the saw with an aluminum oxide blade to cut the locks from the gate, I came across this new material covering the windows. I opened the entrance door and heavy black rolling smoke started to vent from the door opening. The engine received their water and started their attack into the occupancy.
I attempted to vent the windows with my 6' hook and the hook just bounced off — none of the glass shattered. The engine officer was giving instructions to vent the windows and told him I was trying. Undeterred, I then picked up my halligan tool and using the hook end took a major league swing at the glass; it recoiled so fast it just missed my head by inches. But I knew I still had to provide ventilation for the engine so that they could aggressively move in and extinguish the fire. So, I started to remove the framing of the glass with the halligan and I could see that I was making progress.
I removed the whole frame of the window opening, an opening approximately 6' x 6', and pushed the glass forward into the store. This provided enough ventilation to allow the engine to commence attack. I then assisted a couple of other truck members with forcing the remaining three windows that were still intact.
At first I was puzzled and a little upset at not being able to force the windows the conventional way, but being mission orientated I was able to overcome this new obstacle I had never previously encountered and got the job done. Getting back to the firehouse, we discussed what we had encountered and how we were able to overcome and perform the task at hand. Doing a little research, we discovered what this product Lexan was and how we could attack it more efficiently next time. This was 20 years ago.
New materials
Many hazards such as the one I just described have been encountered since then, especially with the new types of lightweight construction materials available today. I wanted to write about Lexan because it will still be encountered today, but not discussed as much as the newer types of materials now available. Many different techniques of removing the Lexan and different types of tools have been tried over the past few years, some with success and other less so.
Lexan has 250 times greater impact resistance than safety glass. It does not shatter and it is basically bullet proof. It is lighter than glass, about half the weight, and also has one-third the conductivity of glass and is self extinguishing. You will find Lexan in high-vandalism areas such as schools and housing projects in lobby areas.
Lexan cannot be broken with conventional forcible entry tools such as the ax and halligan, and even a pike ax is ineffective. The air chisel and the torch also will not work in this situation, while a chainsaw is unsafe since it tends to shatter and throws chips similar to shrapnel.
However, it can be cut easily with a portable power saw equipped with a carbide tip blade. Also effective is the sawzall, with a coarse tooth wood blade, but it is slower than the portable power saw. Forcing subway car windows is easiest done by using a carpet knife to remove the rubber gasket holding the window in place. After cutting and removing the rubber gasket, remove the window by hand — you now have access and egress.
I hope that I have stirred up some ideas in your heads about other ways to effectively force these types of windows. If you should encounter this now semi-ancient product that is prevalent throughout the country, I hope you’ll remember some of the thoughts shared here.
| Discuss this article at FireRescue1 Forums |