Image courtesy of Joe Spych
The discovery of fire was very important, because it allowed cavemen to barbecue hot dogs and make s’mores. But sometimes fires can spread where they shouldn’t, especially if no one planned them. Luckily, there are people like Joe Spych, who fight this kind of fire. Joe is the Deputy Fire Chief for the Bryn Mawr Fire Department. Happily, he kept things cool when he sat down to talk to us about the math involved in his job.
BTM: So, Joe, why do you like being a firefighter?
Joe: Well, it’s great to help people. I’ve wanted to be a firefighter since the 1st grade, when my school took a field trip to a local station. I went home that day and told my Dad I was going to be a firefighter.
BTM: And what does a Deputy Fire Chief do?
Joe: I’m responsible for training all of our firefighters, and I also fulfill the command role at any incident. That means I do a “size-up” where I decide how we’re going to fight a fire or rescue a person.
BTM: Could you explain how your company responds to a fire? What happens once you get a call?
Joe: All the firefighters have a pager that will alert them that there’s a fire, and there’s always someone at the firehouse to answer the call. Typically, within 2 minutes of getting the call, a truck will go out. Once we’re on site, I’ll look at the thickness and color of the smoke to determine the location, size, and stage of the fire. Then I do some quick calculations to know how much water we’re going to need, and where.
BTM: How do you set up the water lines – and how do you use numbers to do that?
Joe: First we connect a supply line to a fire hydrant. There are different-sized hydrants, but in my area, a hydrant has an 8-inch diameter, which means it can put out around 1,200 to 1,500 gallons of water in a minute. That supply line feeds into our truck, where the water is distributed to “attack lines,” the hoses that firefighters carry. Those attack lines pump out 300 gallons a minute, so I need to think about how many attack lines we’ll need and how many supply lines to support them. At the biggest fire I ever fought, we were spraying 3,000 gallons of water per minute, at which point you need to think about how much water weight you’re putting on a building.
BTM: Because a gallon of water weighs 8 pounds?
Joe: Right, so we’re piling on a whole lot of weight to an already-burning structure. Lots of times we need to fight fires “defensively,” which means we don’t have any firefighters inside the structure, and just try to contain the flames.
BTM: So if a kid wants to grow up to be a firefighter, what kind of math should they be learning?
Joe: They would need to have a strong grasp on multiplication and division, as well as measurement. We use something called the Fire Flow Formula to determine how much water we will need to suppress a fire. Basically, you take the area of a building by multiplying its length times its width, and then divide that floor area by 3. That will tell you how many gallons of water per minute you need, and from there, you need to determine the number and placement of attack hoses. Obviously there’s no time to pull out a pencil and paper, so I would recommend practicing some mental math. And it never hurts to be able to estimate measurements, or know how close to a building a 60-foot ladder will have to be to reach the top of a wall that’s 40 feet high. Things happen so quickly at a fire scene that I use math without even thinking twice about it, so kids should get very comfortable with numbers if they want to be a firefighter.