Structure Fires: The People and Science that Puts Them Out

Beep! Beep! Beep! Your properly maintained smoke detector pierces through the silent night. You smell smoke. You gather your wife and children and you all go outside to your meeting place. The fire department arrives on scene, they hook the fire truck up to a fire hydrant, a fire officer walks up to you and asks if everyone is out of the house, and then he walks around your house surveying the scene as the firefighters stretch a fire hose to the door. The firefighters enter your house advancing the hose until they find the fire and vent the smoke out of your house as a coordinated attack, and then they extinguish the fire. They cover your valuables with tarps to eliminate water damage and search to ensure the fire hasn’t spread into unburned areas of your house. They conduct a cause and origin investigation and determine an electrical wire behind your refrigerator had malfunctioned causing your fire.

How many fire trucks are needed to put out your fire? We use a mathematical formula to calculate what we call “fire flow”. Science tells us that fires are sustained chemical reactions that consist of three elements: oxygen, heat, and fuel. There are multiple different ways to extinguish a fire, however the most common extinguishing agent is water. In order for any extinguishing agent to work it must stop the chemical reaction usually by removing one or more of the three elements. Water works to extinguish fire by removing the heat element. The heat released by a fire is measured in units called British Thermal Units or BTUs. The object is to use enough water to overcome the BTUs being released by the fire (heat release rate). The average room fire releases 5,000 to 15,000 BTUs per second. One gallon of water will absorb about 9,000 BTUs per second. Fire flow calculations take all of this information into account to tell us what volume of water, measured in gallons per minute (gpm), is needed based on the dimensions of your structure. There are two formulas to calculate fire flow, the Iowa Formula and the National Fire Academy Formula. Using the Iowa Formula, in a home that is 30 feet x 50 feet (1500 square foot home) that is 10 feet tall (one story) requires a fire flow of 150 gallons per minute (30 x 50 x 10= 15000 /100= 150gpm). The same house using the National Fire Academy Formula responding to a house that appears to be 30ft x 50ft and 25% of it is on fire our formula would be [(30 x 50) /3] x .25= 125 gallons per minute of fire flow is needed in order to extinguish this fire. A single fire hose from a single fire engine with the appropriate nozzle and water pressure can achieve that. In Streator that fire hose (1 ¾” @ 150ft) weighs approximately 156lbs with water. The nozzle is a smoothbore nozzle with a 15/16” tip pumped at 50psi at the nozzle. The firefighter using that nozzle will feel 69lbs of force the entire time they are using that nozzle. The National Fire Protection Association (NFPA) publishes codes & standards for the fire service. While not mandatory they are widely recognized as the industry best practices within and outside of the fire service. That single fire engine should have four firefighters on it according to the National Fire Protection Association’s (NFPA) study on Engine Company Staffing Research (NFPA 1710). This four firefighter crew should include one company officer that must enter the structure with the crew, one firefighter to connect the fire hydrant to the fire truck, one to staff the pump at the fire truck, and two firefighters to enter the structure. In Streator firefighters respond with four individuals in two fire engines. One firefighter will hook up the hydrant, one firefighter will man the pump panel, the Captain and last firefighter will enter the building. Those two will move the 156lb hose line into position and the firefighter will manage the 69lb nozzle reaction. All of these actions will be performed with approximately 100lbs of personal protective equipment on.

What if you were not outside your home? What if you were trapped inside or not home? The firefighters would have searched for you and upon finding you would have removed you from the building. The average adult male weighs 195lbs. After removing you from the building it is likely that the firefighters will continue to help provide medical aid to you. The last time an individual was pulled from a fire by our department the firefighters who pulled him from the fire also initiated CPR, with one firefighter continuing CPR all the way until the individual arrived at the hospital. Traditionally in the fire service the engine company is primarily tasked with extinguishing the fire and a truck (ladder) company is tasked supporting the engine company with forcible entry, ventilation, and search and rescue. NFPA 1710 further continues that a company tasked with search and rescue should similarly be staffed by four firefighters. In Streator the truck (ladder) company is the third vehicle to leave the station (situation may be modified by the Captain dependent on circumstances of the emergency) staffed with call back personnel. That doesn’t mean that if you are trapped in a fire that you will need to wait for this truck company to arrive. The four firefighters arriving on scene prioritize life safety above all other actions on the fire ground. They will take all necessary actions to effect search and rescue while still advancing the hose line to extinguish the fire. “The prompt control and extinguishment of a serious fire is the single most effective lifesaving action a fire department can perform” (1996, Andrew Fredericks). In short if you put the fire out, things get better and advancing the hose line should always be a priority. Regardless you should never doubt at any time that if you are trapped inside a fire, firefighters are coming to get you out.

Finally the Federal Emergency Management Agency Incident Command System requires that all incidents have an incident commander. This incident commander is typically a chief officer who arrives in a car or sports utility vehicle. In Streator our Fire Chief is always on call he responds to all structure fires day and night and assumes the role of Incident Commander. On the rare occasion that he does take a vacation another Captain on our department steps into the acting Chief role.

Furthermore we must have responders staged and ready in the event that a firefighter becomes hurt or otherwise finds themselves in an emergency situation. The Occupational Safety and Health Administration (OSHA) requires fire departments comply with the two in two out rule. If two firefighters go inside a burning building (or other environment immediately dangerous to life and health or IDLH) two firefighters must be outside ready to assist in the event of an emergency. We call these firefighters who are tasked with saving other firefighters the Rapid Intervention Team or RIT. Firefighters on a Rescue Squad fire apparatus or another fire engine can be assigned to this task. Remembering that the average male weighs 195lbs and firefighters wear approximately 100lbs of gear that means that a down firefighter will most likely weigh 295lbs or more. Studies indicate that on average it takes 12 firefighters to remove a downed firefighter from a hazardous environment. The Streator Fire Department currently has 14 firefighters which is short one from our normal staffing of 15.

In order to perform all of the jobs required to adequately work at a 1500 square foot house fire scene requires 4 pieces of fire apparatus and 11 firefighters (NFPA recommends no less than 15 firefighters for a structure fire). We have two shifts of 5 firefighters, one shift of 4 firefighters, and a Fire Chief. Our mandatory minimum manning is 4 firefighters per shift per day because that is the lowest we can have and still comply with OSHA two in two out. When we are dispatched for a house fire four firefighters respond in two fire engines and the Fire Chief responds in his buggy. All of the off duty firefighters have a pager that goes off when there is a fire and we respond to the station and then to the fire. Those first 4-6 firefighters are on their own until the off duty firefighters get dressed, get to the fire station, put on their gear, and then they drive to the fire.

We are regularly asked, how we manage such a heavy workload with so few firefighters? The answer is that we are incredibly efficient, we work very hard, and we are very well trained. We pride ourselves on giving the citizens of Streator the very best, most efficient service for their tax dollar. Streator Fire Department’s Engine Company 2 doesn’t have four firefighters, it has one firefighter that establishes the water supply and mans the panel a task referred to by a veteran FDNY firefighter as the “two minutes of terror”. Engine Company 3 doesn’t have four firefighters, it has three. Engine 3’s responsibility isn’t just to extinguish the fire. They search, ventilate, extinguish, overhaul, and salvage. We have a Fire Chief who is constantly on call, he always monitors some type of radio so that he is ready if we have a call. We are aggressive, we attack the source of the fire and strive to attain rapid extinguishment keeping the fire to the room of origin. Would we be safer if we had more staffing? Absolutely, firefighters from Chicago to Normal, Springfield to Rockford have all remarked about how our low staffing contributes to an increased risk; but we are also committed to working with our citizens to provide the highest quality cost effective fire protection.

This article was originally published on 9/22/2017 as “How many people are on that fire truck?” and has been revisited and published again.