A couple weeks ago I talked about calling a mayday, and how to use it should you find yourself trapped, stuck, or lost. This week I wanted to go along the same lines and talk about something that I have been properly trained to use and keep in my turnouts at all times: a bail out bag.
It is what it says it is, a bag with equipment that I can rescue myself should I become seperated and cut off by fire, and the only way out is through a window or down something that would otherwise call for me to descend a floor or two. I'm going to go through it step by step, and show several videos I found on the subject on YouTube for comparison.
This is a general video about personal escape rope I found, just a general overview of what it is.
There are many types of bags out there, in an effort to provide a level of safety without breaking the bank, I opted for a simple kit that includes 50 ft of 8 mm rope, a section of webbing to guard the rope at chaffing points, a bag to keep the rope in, and two carabiners, one that will come back onto the rope to form a loop and another at the end to keep you from falling or letting you attach it to an anchor point.
The next steps are important, but I must tell you that BEFORE you purchase one of these systems to use, you should find some training on it first and become familiar with the action so you don't fall. However, if you do buy one without training and end up using it and survive then it was a worthwhile investment.
The first step is to admit to yourself that you are trapped/cut off/seperated. The first step to solving any crisis is admitting that you are in trouble.
The next step is to find a window. If you took shelter in a room but the fire is advancing in on you, you will need to do this quickly. Break the window and removed the frame, you will need all the space. If you are fortunate enough to have found a window with a ladder close by or posted at the window by a good truck company then you can use the ladder bail techniques that are taught in any self rescue course.
Now that you have found a window, and have no ladder, you should begin getting ready to bail out. 50 ft of rope is probably enough to get you down 2 or 3 floors. If you are above that you should communicate with the IC via radio and a mayday call that you need a truck to get a ladder up to you. The preparation includes that mayday call and announcing your intention to attempt self rescue.
Using the bag is where the training comes in handy. You will need a hand tool or something sturdy like some piping or if you have the time you can punch out a section of the wall under the window and use the structure itself as an anchor point. Be creative. If you are using a hand tool, create a triangle using the bottom and side of the window frame making the tool the long side of that triangle. Tie the end of the rope into a bowline knot (don't forget your safety knot) and slip over one end of the tool and into the middle of the tool, pulling it tight. I tie the knot in advance to save time.
Now, pull enough line out of the bag and wrap it around yourself. The EVAC system has a section of webbing you can loop between your air pack shoulder straps and create a harness and it uses a figure 8 descender. This simplifies the process, but I learned it the hard way. This being you have to take the rope around you and the pack and grasp where the rope meets itself, creating a bight. You want the rope to be centered about mid-bottle on your pack, this will allow the rope a surface to glide against giving you control and a smooth decent that won't give your gear rope burn.
Get ready to lean out of the window, straddling the window frame. You want to keep tension on the tool, maintaining that triangle with the rope. Stay low to the bottom of the frame and grasp the rope with both hands, one pointing up and one pointing down, so that your thumbs meet. Do not clasp your hands together.
Now you simply roll out of the window, keeping your grip on the rope tight until you are straight up and down.
Now you can loosen your grip on the rope to start your descent. Do it slowly, trying to to get hung up. If you do get snagged, you should be able to giggle a little bit and get the snag free. If not, hang there until someone can get a ladder under you. It is far better to be hanging by a rope than burning up in the fire, and someone should notice a firefighter dangling outside of the building.
This is meant to be done quickly in an emergency, and I found a video of recruits doing this drill, just be aware that in real life, you won't have a belay line.
28 July 2011
19 July 2011
Mayday! Mayday! Mayday!
Crawling down a dark hallway during a fire can be scary enough, but when you get stuck, and it can be a no holds barred fight for life. Put a new firefighter in a wire box and watch them fight and fight and fight to get free and forget the basics of what to do in a self preservation problem. Even many seasoned veterans will let their pride get in the way and will disregard the option. Many others simply don't ever think it could be them.
These mindsets are dangerous. Dangerous for you to have and dangerous to pass on, as the fire environment has changed so much in the past 5 years with the emergence of high density foams, lightweight building construction, and even home ductwork with wire or open runs of telephone wire, there are plenty of ways to become trapped by fire, stuck in a collapse, and tangled in a ton of wire.
These are just a few examples of the threat posed to the firefighter in the fire environment, and not all inclusive. Buildings today are built "on the cheap" with little consideration for the survivability of the structure and usually only with minimum fire safety standards. Ever seen a McDonald's under construction? They are lightweight, top-loaded buildings and are designed to be disposable. Burn one up and guaranteed it will be torn down a few days later, and three months after that another one will be up in the same place.
So what can you do to avoid being trapped in a building fire? Well, you must maintain situational awareness at all times. Be cognizant of your surroundings. Listen to the building, if you hear groans and creaks and if it sounds like the building is going to come down, you should bring that up to your officer. On the outside looks for sagging roofs, cracks in the concrete or mortar, walls bending in directions they shouldn't. Any situation that looks overly dangerous should be reported to your officer, and if you're the officer, tell the IC.
So now the big part, what should you do when you get trapped? Your first steps are the ones that will save your bacon. The first is to calm down, wait, let me repeat that:
CALM DOWN!!!!!!!!!
If you get to fighting and struggling against something you can't see, you are going to both waste your air, tire yourself, and delay getting help to you. Ever seen the video of the Captain that got lost in that high rise in Houston? He called the mayday, but was panicking as well. Your radio transmission will be understood better if you are calm. On a side note, talking in a normal tone into your radio mic will reduce the amount of interference heard on the other end.
Your next step is to call a LUNAR report. LUNAR means:
Location - where you think you are or your last known position
Unit - who you are with, and it may not be who you are normally assigned to
Name - who you are so they can figure it out on the personnel board
Assignment - what you are supposed to be doing AT THE FIRE, not what company you are assigned to
Resources - what you need to get free. Tangled in wires, trapped under something? Wire cutters and power tools will set you free!
Now that you've called for help, and it is coming to you, you can try and free yourself. If you can't after a few minutes, conserve your air until help arrives.
Maybe in the future we'll talk about self rescue techniques, but they are better shown and done in person than explained. Search out the training in our area and get that self rescue training. Learn how to use a bail out bag, then go out and buy one with some flashlights. They are investments in your life, and nothing is worth more...
These mindsets are dangerous. Dangerous for you to have and dangerous to pass on, as the fire environment has changed so much in the past 5 years with the emergence of high density foams, lightweight building construction, and even home ductwork with wire or open runs of telephone wire, there are plenty of ways to become trapped by fire, stuck in a collapse, and tangled in a ton of wire.
These are just a few examples of the threat posed to the firefighter in the fire environment, and not all inclusive. Buildings today are built "on the cheap" with little consideration for the survivability of the structure and usually only with minimum fire safety standards. Ever seen a McDonald's under construction? They are lightweight, top-loaded buildings and are designed to be disposable. Burn one up and guaranteed it will be torn down a few days later, and three months after that another one will be up in the same place.
So what can you do to avoid being trapped in a building fire? Well, you must maintain situational awareness at all times. Be cognizant of your surroundings. Listen to the building, if you hear groans and creaks and if it sounds like the building is going to come down, you should bring that up to your officer. On the outside looks for sagging roofs, cracks in the concrete or mortar, walls bending in directions they shouldn't. Any situation that looks overly dangerous should be reported to your officer, and if you're the officer, tell the IC.
So now the big part, what should you do when you get trapped? Your first steps are the ones that will save your bacon. The first is to calm down, wait, let me repeat that:
CALM DOWN!!!!!!!!!
If you get to fighting and struggling against something you can't see, you are going to both waste your air, tire yourself, and delay getting help to you. Ever seen the video of the Captain that got lost in that high rise in Houston? He called the mayday, but was panicking as well. Your radio transmission will be understood better if you are calm. On a side note, talking in a normal tone into your radio mic will reduce the amount of interference heard on the other end.
Your next step is to call a LUNAR report. LUNAR means:
Location - where you think you are or your last known position
Unit - who you are with, and it may not be who you are normally assigned to
Name - who you are so they can figure it out on the personnel board
Assignment - what you are supposed to be doing AT THE FIRE, not what company you are assigned to
Resources - what you need to get free. Tangled in wires, trapped under something? Wire cutters and power tools will set you free!
Now that you've called for help, and it is coming to you, you can try and free yourself. If you can't after a few minutes, conserve your air until help arrives.
Maybe in the future we'll talk about self rescue techniques, but they are better shown and done in person than explained. Search out the training in our area and get that self rescue training. Learn how to use a bail out bag, then go out and buy one with some flashlights. They are investments in your life, and nothing is worth more...
14 July 2011
For A Fallen Public Servant
Some may not have been paying attention to the night I was updating about an officer being shot in downtown Memphis.
The story was that earlier in the evening, several men were at a family reunion on Beale Street when things turned violent, a man was assaulting his wife, and her ex-husband stepped in to intervene. The assaulter, went back to his hotel room and retrieved a pistol and shot the man dead when he returned to the hotel later that evening. The 911 call went out, and Officer Timothy Warren responded. As he made his way up the stairs, he was ambushed by the suspect, sustaining a later fatal gunshot wound to the head.
Officer Warren left behind a wife and two young girls.
We often ask how can we help in these times, or what can we do. Someone provided an answer.
My friend Angie and her daughters were so impressed by the life of Officer Warren that they started a way to raise a little money for the Warren family in their time of need, and I felt hat it needed to be spread across the internet.
Officer Warren was a man living in two worlds. The toughness of being a police officer and the kind heartedness of ministry. MotorCop blogged on this already so I'll spare you a repeat, but it is important that we do something, we would want someone to do the same for us.
So I invite you to make a small donation to Girls in Pink Supporting Boys in Blue. They are selling T-shirts with proceeds to go to the Warren family.
Here are the details:
They have sold nearly 500 so far and are starting a second batch soon, so get yours on this next order and send a few dollars to a needy family. We could all use the good karma these days.
The story was that earlier in the evening, several men were at a family reunion on Beale Street when things turned violent, a man was assaulting his wife, and her ex-husband stepped in to intervene. The assaulter, went back to his hotel room and retrieved a pistol and shot the man dead when he returned to the hotel later that evening. The 911 call went out, and Officer Timothy Warren responded. As he made his way up the stairs, he was ambushed by the suspect, sustaining a later fatal gunshot wound to the head.
Officer Warren left behind a wife and two young girls.
We often ask how can we help in these times, or what can we do. Someone provided an answer.
My friend Angie and her daughters were so impressed by the life of Officer Warren that they started a way to raise a little money for the Warren family in their time of need, and I felt hat it needed to be spread across the internet.
Officer Warren was a man living in two worlds. The toughness of being a police officer and the kind heartedness of ministry. MotorCop blogged on this already so I'll spare you a repeat, but it is important that we do something, we would want someone to do the same for us.
So I invite you to make a small donation to Girls in Pink Supporting Boys in Blue. They are selling T-shirts with proceeds to go to the Warren family.
 |
| Front |
 |
| Back |
- Go to Paypal.com
- Log in, or send money without logging in
- Enter in the PayPal ID: GIPSBIN@yahoo.com
- Enter your:
- Name
- Home Address
- Phone Number
- Shirt sizes and color (pink or black)
They have sold nearly 500 so far and are starting a second batch soon, so get yours on this next order and send a few dollars to a needy family. We could all use the good karma these days.
12 July 2011
Water Anyone?
@Darthtater_911 (a Metro Louisville firefighter) shot this picture of a water main break in Louisville. I would say that might cause a bit of a supply problem.
Which makes me wonder, when you're at the panel, what's your static pressure? Your residual? Do you remember? When is it safe and not safe to flow another line?
You get good enough pressure at the plug to not need a nurse pumper? Do you "take your own plugs?"
Take this moment to review your water supply procedures.
Fire Attack Operations
There is often much contention between firefighters about who is the most important, the truckies or the pipemen? Although I like spraying water as much as the next guy, I've always been a truckie at heart. That being said, the engine company is one of the most vital parts of the strategy, because you need to spray water to put out the fire. True that it will eventually burn itself out, but one of the main fire service tenants is to conserve property, and letting it burn doesn't match up with that priority.
The idea behind fire attack has always been to put water on the fire, and that idea has changed much over the years. The fire service used to be dominated by straight tipped nozzles that sprayed out a solid stream of water. In the 1950's Lloyd Laymen, former Chief of the US Coast Guard Fire Training Center, devised a new form of fire attack using a fog nozzle. This was an idea imported from the naval services, since they used fog nozzles to control shipboard fires quickly. The new concept was adopted by the mainstream fire service quickly, but there was a catch...
Laymen never actually intended for the fog nozzle to be used in an interior attack mode. That's right, not go to an interior attack. This misunderstanding was quickly applied and often with disastrous results. It was continued up until the 1980's, when smooth nozzles started to become common place again, but even today they are far less common than prior to the advent of the fog nozzle. Smooth nozzles require a lot more skill to use and are far easier to handle because of low nozzle reaction. Remember Newton's First Law? Every action has an equal and opposite reaction? The more pressure you pump to a nozzle the higher the reaction force at the point of discharge will be, so if you are pumping 100 psi to a nozzle, you will be getting an equal amount of reaction force at the nozzle.
So the attack REALLY starts before you even make it to the fire. You should familiarize yourself with what you have available, and what your hose lines can do. This is only achievable through study and training. Waiting until you are at the fire to become familiar with your gear is not the right moment. Often individual shifts or in the case of volunteer services, individuals themselves, will prefer a different set up based on their chief or company officer's beliefs. If you are not part of that shift, you need to pay attention what nozzle or hand tools have been misplaced or moved and either move them back or remember where they are.
Often hose will be removed at a fire and may not be replaced. You should keep note of how many sections of hose you have pre-connected or in the beds so you will not "lay out short" and need to stretch additional hose to make up the difference.
As a company officer, the size of the initial line makes a difference in how quickly you get a stop on a fire. The heat release curve states that the maximum heat release is achieved during a free burning period just after flashover, but is not maintained for very long, and eventually burns down into a smoldering state. With this in mind, remember that using a small handline (1.75 inch, usually) while the fire is post-flashover and into a free burning state will not do much. The application of water is directly proportional to the heat release curve, meaning that if you do not apply enough water to combat the heat release of burning materials, you will be getting nowhere on the fire, and it may even advance on you. Lines in excess of 2 inches are preferred. They are not easy to manage when charged and require extra muscle to position, but you will not be fighting fire for very long.
This is where the discussion on nozzles comes in. If you are pumping 150 psi to a fog nozzle on the end of a large handline there will be a HUGE difference in reaction force opposed to 50 or 75 psi, with better flow from the smooth nozzle because there is less in the nozzle itself to impede flow.
Something that is very rarely considered is the air flow into the fire area, which can rapidly change the conditions. A fog nozzle even at a 30 degree fog pattern will entrain over 1000 ft3 of air into the air. This when combined with water hitting superheated materials and converting to steam will produce a steam flow along the path of least resistance (which is usually the path the hose team traveled) and push superheated gas back onto the hose team. This is disrupting the thermal layer, and without ventilation to create that path of least resistance.
Once you have worked your line into position and it's charged, you can now spray water. There is no hard and fast rule, but there are some things to keep in mind. If you spray water directly on what's burning, you will scatter it all over. I prefer an indirect spray pattern regardless of what nozzle you are using. The circular pattern is the easiest to remember and easiest to do, and doesn't involve sharp movements of the nozzle. You should spray water so that it hits both walls, the ceiling, and the floor.
Why the floor? This allows you to use the water stream to sweep the floor of debris that falls in your path as well as cooling the area where you will soon be crawling or walking.
Once you have extinguished the fire, you will be moving immediately into the overhaul phase, but that's another article...
The idea behind fire attack has always been to put water on the fire, and that idea has changed much over the years. The fire service used to be dominated by straight tipped nozzles that sprayed out a solid stream of water. In the 1950's Lloyd Laymen, former Chief of the US Coast Guard Fire Training Center, devised a new form of fire attack using a fog nozzle. This was an idea imported from the naval services, since they used fog nozzles to control shipboard fires quickly. The new concept was adopted by the mainstream fire service quickly, but there was a catch...
Laymen never actually intended for the fog nozzle to be used in an interior attack mode. That's right, not go to an interior attack. This misunderstanding was quickly applied and often with disastrous results. It was continued up until the 1980's, when smooth nozzles started to become common place again, but even today they are far less common than prior to the advent of the fog nozzle. Smooth nozzles require a lot more skill to use and are far easier to handle because of low nozzle reaction. Remember Newton's First Law? Every action has an equal and opposite reaction? The more pressure you pump to a nozzle the higher the reaction force at the point of discharge will be, so if you are pumping 100 psi to a nozzle, you will be getting an equal amount of reaction force at the nozzle.
So the attack REALLY starts before you even make it to the fire. You should familiarize yourself with what you have available, and what your hose lines can do. This is only achievable through study and training. Waiting until you are at the fire to become familiar with your gear is not the right moment. Often individual shifts or in the case of volunteer services, individuals themselves, will prefer a different set up based on their chief or company officer's beliefs. If you are not part of that shift, you need to pay attention what nozzle or hand tools have been misplaced or moved and either move them back or remember where they are.
Often hose will be removed at a fire and may not be replaced. You should keep note of how many sections of hose you have pre-connected or in the beds so you will not "lay out short" and need to stretch additional hose to make up the difference.
As a company officer, the size of the initial line makes a difference in how quickly you get a stop on a fire. The heat release curve states that the maximum heat release is achieved during a free burning period just after flashover, but is not maintained for very long, and eventually burns down into a smoldering state. With this in mind, remember that using a small handline (1.75 inch, usually) while the fire is post-flashover and into a free burning state will not do much. The application of water is directly proportional to the heat release curve, meaning that if you do not apply enough water to combat the heat release of burning materials, you will be getting nowhere on the fire, and it may even advance on you. Lines in excess of 2 inches are preferred. They are not easy to manage when charged and require extra muscle to position, but you will not be fighting fire for very long.
This is where the discussion on nozzles comes in. If you are pumping 150 psi to a fog nozzle on the end of a large handline there will be a HUGE difference in reaction force opposed to 50 or 75 psi, with better flow from the smooth nozzle because there is less in the nozzle itself to impede flow.
Something that is very rarely considered is the air flow into the fire area, which can rapidly change the conditions. A fog nozzle even at a 30 degree fog pattern will entrain over 1000 ft3 of air into the air. This when combined with water hitting superheated materials and converting to steam will produce a steam flow along the path of least resistance (which is usually the path the hose team traveled) and push superheated gas back onto the hose team. This is disrupting the thermal layer, and without ventilation to create that path of least resistance.
Once you have worked your line into position and it's charged, you can now spray water. There is no hard and fast rule, but there are some things to keep in mind. If you spray water directly on what's burning, you will scatter it all over. I prefer an indirect spray pattern regardless of what nozzle you are using. The circular pattern is the easiest to remember and easiest to do, and doesn't involve sharp movements of the nozzle. You should spray water so that it hits both walls, the ceiling, and the floor.
Why the floor? This allows you to use the water stream to sweep the floor of debris that falls in your path as well as cooling the area where you will soon be crawling or walking.
Once you have extinguished the fire, you will be moving immediately into the overhaul phase, but that's another article...
08 July 2011
Wildland Firefighting for the Structural Firefighter Part II
Continuation
Firefighting in the wildland environment is tough for the structural firefighter, so what can you use that you already have?
As we discussed earlier, we don't have the specialized equipment or gear in order to fight a wildfire like the Forest Service, but we can successfully control the incident using basic tactics and the benefit of high water flows. For instance, take the following scenario.
Situation
You are dispatched to a reported brush fire in a river bottom, which under normal circumstances is dry but filled with soft dirt and thick vegetation. It is often used by indigent people to set up tent cities due to it being secluded and away from the public view. Most often the cause of these fires is unattended camp fires. As you leave the station, you see a large plume of smoke and a helicopter circling around it.
You arrive to find a police officer pointing you back to an area at the end of a long path. The path appears to be soft dirt, but is narrow and stable enough to be able to move the large engine back into the bottoms. The fire is over a large area and is spreading rapidly in dry grass and light winds out of the south west. The driver puts the engine into pump gear and charges the booster reel, a 1" rubber jacketed line about 300' in length.
You grab a pike pole while the other firefighter takes the nozzle and begins knocking the fire away from the road and extinguishes the materials you pull apart with your pike pole.
The nozzle man advances into the burned area in an attempt to keep the fire from spreading (direct attack) while you use the pike pole to pull burning materials away from the fire in and into the burned area. The nozzle man fogs his stream out to suppress a large area. The next engine company establishes a water supply using 5" hose, and connects to a third arriving pumper for a relay operation. The booster lines are ordered to back out and the deck guns on two pumpers pinch the fire between the master streams and cut off it's advance, then the booster reels move in to mop up.
The incident takes longer than anticipated, the ground has been used to dump tree stumps, and several are now hiding the fire within their stacks. A track hoe is called in to bury the stumps and clear the land.
Lessons Learned and Things to Remember
Weather patterns played a major role in fire spread, and coupled with late detection, allowed the fire to spread unchecked. Had the fire not been detected, it could possibly have taken over the whole area.
Knowing what the fire is doing and it's direction of spread played a factor in the placement of equipment and eventually how it was contained. The deployment of master streams allowed the firefighting effort to extend past the reach of booster reels and used enough water to suppress the fire at a distance, reducing crew fatigue.
Radios allowed coordination of the master streams using spotters to guide them in, communication was key in the effort and a lot of information regarding fire spread and extinguishment progress was communicated back to incident commander.
This incident came to a successful conclusion because of communications and teamwork as well as the adaptability of the firefighters to use what was available to contain what could have become a large wildfire.
Firefighting in the wildland environment is tough for the structural firefighter, so what can you use that you already have?
As we discussed earlier, we don't have the specialized equipment or gear in order to fight a wildfire like the Forest Service, but we can successfully control the incident using basic tactics and the benefit of high water flows. For instance, take the following scenario.
Situation
You are dispatched to a reported brush fire in a river bottom, which under normal circumstances is dry but filled with soft dirt and thick vegetation. It is often used by indigent people to set up tent cities due to it being secluded and away from the public view. Most often the cause of these fires is unattended camp fires. As you leave the station, you see a large plume of smoke and a helicopter circling around it.
You arrive to find a police officer pointing you back to an area at the end of a long path. The path appears to be soft dirt, but is narrow and stable enough to be able to move the large engine back into the bottoms. The fire is over a large area and is spreading rapidly in dry grass and light winds out of the south west. The driver puts the engine into pump gear and charges the booster reel, a 1" rubber jacketed line about 300' in length.
You grab a pike pole while the other firefighter takes the nozzle and begins knocking the fire away from the road and extinguishes the materials you pull apart with your pike pole.
The nozzle man advances into the burned area in an attempt to keep the fire from spreading (direct attack) while you use the pike pole to pull burning materials away from the fire in and into the burned area. The nozzle man fogs his stream out to suppress a large area. The next engine company establishes a water supply using 5" hose, and connects to a third arriving pumper for a relay operation. The booster lines are ordered to back out and the deck guns on two pumpers pinch the fire between the master streams and cut off it's advance, then the booster reels move in to mop up.
The incident takes longer than anticipated, the ground has been used to dump tree stumps, and several are now hiding the fire within their stacks. A track hoe is called in to bury the stumps and clear the land.
Lessons Learned and Things to Remember
Weather patterns played a major role in fire spread, and coupled with late detection, allowed the fire to spread unchecked. Had the fire not been detected, it could possibly have taken over the whole area.
Knowing what the fire is doing and it's direction of spread played a factor in the placement of equipment and eventually how it was contained. The deployment of master streams allowed the firefighting effort to extend past the reach of booster reels and used enough water to suppress the fire at a distance, reducing crew fatigue.
Radios allowed coordination of the master streams using spotters to guide them in, communication was key in the effort and a lot of information regarding fire spread and extinguishment progress was communicated back to incident commander.
This incident came to a successful conclusion because of communications and teamwork as well as the adaptability of the firefighters to use what was available to contain what could have become a large wildfire.
07 July 2011
"Cheat Sheets" and "the Culture of Extinguishment"
I've been in the business for about 10 years now, and I learned a lot of things the hard ways first, especially operating fire pumps. I learned all the mental calculations and solutions to fireground water supply problems and then having those concepts drilled into me until I could recall them instantly.It was old fashioned learning taught in an old fashioned way and it was quite effective.
I was thinking the other day about things that we all could do better, and thinking on the idea of checklists, I realized that despise the idea of cheat sheets. Checklist, ok, that follows a logical form that acts as a memory aid. A cheat sheet by my definition is a memory aid that gives you the answers as opposed to making sure you followed the steps correctly. I have seen them in a lot of places, and none more so on the topic of pump operations at a fire scene.
Maybe it comes back to my background and style of training. We were trained and educated that fireground objectives and the processes by which tactics are achieved (water supply, attack, search, etc) be initiated quickly and without time to consult a cheat sheet on how to achieve draft or what to set the discharge pressure at the pump at. All of this should be pre-recorded in the operator's mind or anyone that may be called upon to drive. I have seen some operators simply set the pump to a low engine pressure dictated by policy and go about doing other things. Meanwhile, the nozzle (a fog nozzle working to create a stream) creates a pretty stream with no reach or power and calls for more pressure go unheeded, or not heard. That, in my mind, is how people get burned. We must think about supplying adequate water to the attack team, or the attack will fail. I will be dedicating more time to basic firefighting skills and more fire science in the near future.
Some have started to see the success of a firefighting operation as "no one got hurt." I disagree, that is only one of the measures of a successful operation. Looking at only one dimension is not doing the citizens that called us for help a service, other than saving them some tax money paying for OJI benefits because someone got hurt or killed. When people all the fire department they expect that someone is going to show up and extinguish the fire, not letting the building go to the ground unless it was absolutely necessary.
Ray McCormack said it best that we need a culture of extinguishment and not safety. I agree and disagree, we should have a culture of extinguishment while doing it safely, but taking risks when we must. Risk a lot to save a lot, risk little to save little.
Try that on a cheat sheet.
I was thinking the other day about things that we all could do better, and thinking on the idea of checklists, I realized that despise the idea of cheat sheets. Checklist, ok, that follows a logical form that acts as a memory aid. A cheat sheet by my definition is a memory aid that gives you the answers as opposed to making sure you followed the steps correctly. I have seen them in a lot of places, and none more so on the topic of pump operations at a fire scene.
Maybe it comes back to my background and style of training. We were trained and educated that fireground objectives and the processes by which tactics are achieved (water supply, attack, search, etc) be initiated quickly and without time to consult a cheat sheet on how to achieve draft or what to set the discharge pressure at the pump at. All of this should be pre-recorded in the operator's mind or anyone that may be called upon to drive. I have seen some operators simply set the pump to a low engine pressure dictated by policy and go about doing other things. Meanwhile, the nozzle (a fog nozzle working to create a stream) creates a pretty stream with no reach or power and calls for more pressure go unheeded, or not heard. That, in my mind, is how people get burned. We must think about supplying adequate water to the attack team, or the attack will fail. I will be dedicating more time to basic firefighting skills and more fire science in the near future.
Some have started to see the success of a firefighting operation as "no one got hurt." I disagree, that is only one of the measures of a successful operation. Looking at only one dimension is not doing the citizens that called us for help a service, other than saving them some tax money paying for OJI benefits because someone got hurt or killed. When people all the fire department they expect that someone is going to show up and extinguish the fire, not letting the building go to the ground unless it was absolutely necessary.
Ray McCormack said it best that we need a culture of extinguishment and not safety. I agree and disagree, we should have a culture of extinguishment while doing it safely, but taking risks when we must. Risk a lot to save a lot, risk little to save little.
Try that on a cheat sheet.
05 July 2011
Wildland Firefighting for the Structural Firefighter Part I
Another re-post
It is not uncommon for a structural firefighter to make a grass fire once or twice a year, but what is supposed to happen when the situation becomes larger? Structural firefighters are faced with a challenge that does not occur that often, and are often ill prepared for. I will attempt to break down some basic wildland concepts so that you will be prepared for your next wildland fire.
There are several immediate differences between structural and wildland firefighters. Standing side by side, the type of protective equipment we use is heavier and more bulky, meant to protect us from high heat inside an enclosed space. If you have fought a wildland fire in structural gear, you know that it reduces your mobility and makes handling lines and doing work that much more difficult. Conversely, the protective equipment worn by wildland firefighters is light and made of lightweight, breathable, all natural materials such as cotton and leather. This is meant for mobility and protection as natural materials have a higher heat resistance than some synthetics. It allows for the wildland firefighter to fight fire on the move, being able to pack up and move quickly to redeploy elsewhere.
Our increased weight does not allow us to be deployed for an extended period of time. The wildland firefighter is equipped for work for days in the forest, carrying all the necessities of life with him in addition to firefighting equipment. Wildland firefighters often carry different tools. A pulaski axe, for example, is both and axe and an adze on a single head, used for both digging and chopping. Smaller hose sizes allow for the wildland firefighter to be able to operate a single line without help, decreasing fatigue.
So what does the structural firefighter need to know in order to safely and effectively handle wildland fires?
The answer is multifaceted.
The US Forest Service has the 10 Standard Firefighting Orders, which are a good basis to start on
It is not uncommon for a structural firefighter to make a grass fire once or twice a year, but what is supposed to happen when the situation becomes larger? Structural firefighters are faced with a challenge that does not occur that often, and are often ill prepared for. I will attempt to break down some basic wildland concepts so that you will be prepared for your next wildland fire.
There are several immediate differences between structural and wildland firefighters. Standing side by side, the type of protective equipment we use is heavier and more bulky, meant to protect us from high heat inside an enclosed space. If you have fought a wildland fire in structural gear, you know that it reduces your mobility and makes handling lines and doing work that much more difficult. Conversely, the protective equipment worn by wildland firefighters is light and made of lightweight, breathable, all natural materials such as cotton and leather. This is meant for mobility and protection as natural materials have a higher heat resistance than some synthetics. It allows for the wildland firefighter to fight fire on the move, being able to pack up and move quickly to redeploy elsewhere.
Our increased weight does not allow us to be deployed for an extended period of time. The wildland firefighter is equipped for work for days in the forest, carrying all the necessities of life with him in addition to firefighting equipment. Wildland firefighters often carry different tools. A pulaski axe, for example, is both and axe and an adze on a single head, used for both digging and chopping. Smaller hose sizes allow for the wildland firefighter to be able to operate a single line without help, decreasing fatigue.
So what does the structural firefighter need to know in order to safely and effectively handle wildland fires?
The answer is multifaceted.
The US Forest Service has the 10 Standard Firefighting Orders, which are a good basis to start on
- Keep informed on fire weather conditions and forecasts.
- Know what your fire is doing at all times.
- Base all actions on current and expected behavior of the fire.
- Identify escape routes and safety zones and make them known.
- Post lookouts when there is possible danger.
- Be alert. Keep calm. Think clearly. Act decisively.
- Maintain prompt communications with your forces, your supervisor, and adjoining forces.
- Give clear instructions and insure they are understood.
- Maintain control of your forces at all times.
- Fight fire aggressively, having provided for safety first.
They expanded on these later, creating the 18 Watchout Situations:
- Fire not scouted and sized up.
- In country not seen in daylight.
- Safety zones and escape routes not identified.
- Unfamiliar with weather and local factors influencing fire behavior.
- Uninformed on strategy, tactics, and hazards.
- Instructions and assignments not clear.
- No communication link with crewmembers/supervisors.
- Constructing line without safe anchor point.
- Building fireline downhill with fire below.
- Attempting frontal assault on fire.
- Unburned fuel between you and the fire.
- Cannot see main fire, not in contact with anyone who can.
- On a hillside where rolling material can ignite fuel below.
- Weather is getting hotter and drier.
- Wind increases and/or changes direction.
- Getting frequent spot fires across line.
- Terrain and fuels make escape to safety zones difficult.
- Taking a nap near the fire line.
So how can structural firefighters safely handle wildland fires, even though we are placed at a disadvantage?
Remember what we know about fire already and how to attack it, we will most often be fighting the fire from behind and directly extinguishing burning fuels themselves in a "direct attack." Because of the potential for fire spread, it is not recommended that a direct attack be made form in front of the fire (see #10 of the 18 warning signs) because you could become overwhelmed by the fire front.
However there will be occasions where the fire has grown outside of ability to control it directly. While this is rare, it is an option that needs to be considered. An "indirect attack" involves the cutting of fire breaks and lighting a backfire, or creation of spot fires that are then extinguished in the fire's path. Either method allows the fire to burn itself out by consuming all the fuels between the fire break and main fire. In the urban interface this is a last option as it involves equipment we do not readily have on hand such as bulldozers and if a Forest Service or wildland resource management (many states have these in state parks) crew is available they should be contacted for assistance, since this tactic requires specialists as the potential for the backfire to spread is great.
Now that he have discussed a little strategy, in the next installment we will discuss what structural firefighters can do to control the spread of a wildland fire using the equipment they already have available.
Now that he have discussed a little strategy, in the next installment we will discuss what structural firefighters can do to control the spread of a wildland fire using the equipment they already have available.
03 July 2011
Bread and Butter House Fire
Scenario
You are assigned to an engine company in a mid to low income area of your city. Your engine is staffed with four personnel, a dedicated driver, an officer, and another firefighter in addition to yourself. Around midnight, you are dispatched to a house on fire. The address isn't specific. Typically, nonspecific address calls mean either the caller was passing by wasn't sure what they saw or are false calls (calls that originate but the occupants or neighbors didn't call). However, the CAD printer rolls a 2nd time dispatching your station's ambulance to the call (when this happens before the first engine arrives it means that multiple calls have been received. Multiple calls lend more legitimacy).
You don't notice a smoke plume, but it is dark outside and the passing street lights don't offer much illumination. As you come down the street, the ambulance (which was out of the house) arrives first and informs your officer that there is fire showing in the rear of the farthest window from the street they are positioned on. As you arrive a few seconds later the fire is visible, shooting from the window. The structure is a single story apartment building with four separate units, wood framed with brick veneer. From the exterior it is estimated that the structure is 10% involved
You pull a 150' 1-3/4" attack line from the bed and advance the line to the door closest the street. A member of another company forces the door while you put on your SCBA facepiece. They inform you and your officer that the door is blocked and go around the other side of the structure. You see the smoke coming out of the door and push the door in, then shove a table from behind the door out of the way. As you look in, you are informed that another entrance on the side is open and clear (the arrow in the exterior diagram). You reposition and wait for your line to charge before advancing. Another firefighter is ahead of you searching as he advances.
You locate the fire in the the rear of the structure in the bedroom, the approximate location of the window you observed when you turned on to the street. A window A/C unit is involved in fire and the flames have worked up over the room into the attic space. You extinguish this fire and the fire extending to the eves over the bedroom. The truck company on the exterior has placed a PPV fan at the first entrance and powers the smoke and heat out of the room. You can see that the bed has been burned up and a power cable to the A/C unit is partially burned. The truck company pulls ceiling around the point of origin and locates additional fire burning up the roof joists. This is extinguished and the fire is placed under control.
Discussion
This is a classic example of common household fires. They do not usually get big enough to destroy a house when they are detected quickly but between ignition and suppression they generate a lot of smoke and heat. The initial report from the ambulance crew gave us a quick summary of what we would be facing, and from the exterior it appeared that there would be a lot of fire to deal with. The decision was made to attack with a 200 gpm nozzle due to the potential for structural involvement, and during overhaul it was discovered that the structure was minimally involved. This is a textbook operation as well as the standard procedure when the structure is involved. It is procedure to under pressurize the attack line at 90 psi until a water source can be established. Due to the proximity of a water source to the attack engine the line was brought to the full pressure of 100 psi while a connection using soft sleeve 5" hose was made.
Forcible entry was required due the security doors and bars on access points. This area is considered a high crime area, so it is not uncommon for additional hard security features to be installed. This can delay access to both the fire and trapped occupants, and as the fire grows the environment becomes more and more untenable for occupants who may be trapped inside. Visual examination of the wood around the point of ignition and other contents in the room suggest that the fire was never able to reach flashover (approx 1000 degrees F) but was hot enough to ignite the window frame, the eves of the roof directly over the window, and burn the roof rafters and roof sheeting. No insulation was present in the roof structure.
Lessons Learned and Conclusion
Be wary of exterior doors, especially when there are multiple entrance points. Occupants will block them to use the space (in this case, a kitchen table. The fire may appear larger on the exterior than the interior, but it is always a good idea to use a larger handline if it is believed that the structural components are involved. In this case, no rescue was necessary as the occupants were not at home, but it would have been difficult to access them if there were due to the security doors and bars. PPV proceeded quickly due to the point of origin being a window itself, no hole was cut in the roof as the fire was controlled rapidly.
\The point of origin was determined to be the window A/C unit. No investigator was needed and the fire was ruled accidental.
You are assigned to an engine company in a mid to low income area of your city. Your engine is staffed with four personnel, a dedicated driver, an officer, and another firefighter in addition to yourself. Around midnight, you are dispatched to a house on fire. The address isn't specific. Typically, nonspecific address calls mean either the caller was passing by wasn't sure what they saw or are false calls (calls that originate but the occupants or neighbors didn't call). However, the CAD printer rolls a 2nd time dispatching your station's ambulance to the call (when this happens before the first engine arrives it means that multiple calls have been received. Multiple calls lend more legitimacy).
You don't notice a smoke plume, but it is dark outside and the passing street lights don't offer much illumination. As you come down the street, the ambulance (which was out of the house) arrives first and informs your officer that there is fire showing in the rear of the farthest window from the street they are positioned on. As you arrive a few seconds later the fire is visible, shooting from the window. The structure is a single story apartment building with four separate units, wood framed with brick veneer. From the exterior it is estimated that the structure is 10% involved
You pull a 150' 1-3/4" attack line from the bed and advance the line to the door closest the street. A member of another company forces the door while you put on your SCBA facepiece. They inform you and your officer that the door is blocked and go around the other side of the structure. You see the smoke coming out of the door and push the door in, then shove a table from behind the door out of the way. As you look in, you are informed that another entrance on the side is open and clear (the arrow in the exterior diagram). You reposition and wait for your line to charge before advancing. Another firefighter is ahead of you searching as he advances.
You locate the fire in the the rear of the structure in the bedroom, the approximate location of the window you observed when you turned on to the street. A window A/C unit is involved in fire and the flames have worked up over the room into the attic space. You extinguish this fire and the fire extending to the eves over the bedroom. The truck company on the exterior has placed a PPV fan at the first entrance and powers the smoke and heat out of the room. You can see that the bed has been burned up and a power cable to the A/C unit is partially burned. The truck company pulls ceiling around the point of origin and locates additional fire burning up the roof joists. This is extinguished and the fire is placed under control.
Discussion
This is a classic example of common household fires. They do not usually get big enough to destroy a house when they are detected quickly but between ignition and suppression they generate a lot of smoke and heat. The initial report from the ambulance crew gave us a quick summary of what we would be facing, and from the exterior it appeared that there would be a lot of fire to deal with. The decision was made to attack with a 200 gpm nozzle due to the potential for structural involvement, and during overhaul it was discovered that the structure was minimally involved. This is a textbook operation as well as the standard procedure when the structure is involved. It is procedure to under pressurize the attack line at 90 psi until a water source can be established. Due to the proximity of a water source to the attack engine the line was brought to the full pressure of 100 psi while a connection using soft sleeve 5" hose was made.
Forcible entry was required due the security doors and bars on access points. This area is considered a high crime area, so it is not uncommon for additional hard security features to be installed. This can delay access to both the fire and trapped occupants, and as the fire grows the environment becomes more and more untenable for occupants who may be trapped inside. Visual examination of the wood around the point of ignition and other contents in the room suggest that the fire was never able to reach flashover (approx 1000 degrees F) but was hot enough to ignite the window frame, the eves of the roof directly over the window, and burn the roof rafters and roof sheeting. No insulation was present in the roof structure.
Lessons Learned and Conclusion
Be wary of exterior doors, especially when there are multiple entrance points. Occupants will block them to use the space (in this case, a kitchen table. The fire may appear larger on the exterior than the interior, but it is always a good idea to use a larger handline if it is believed that the structural components are involved. In this case, no rescue was necessary as the occupants were not at home, but it would have been difficult to access them if there were due to the security doors and bars. PPV proceeded quickly due to the point of origin being a window itself, no hole was cut in the roof as the fire was controlled rapidly.
\The point of origin was determined to be the window A/C unit. No investigator was needed and the fire was ruled accidental.
01 July 2011
Fire Behavior
This is a re-post of one of my previous posts on my older blog
Kind of got a request via Twitter, and in answering this request I had to break out my old fire behavior books from college.
I'm a big "back to basics" guy, as I think sometimes we focus too much on the advanced stuff rather than mastering the basics. This seems to be true in most aspects of where I work. We want to play with the big toys, which are the most fun, without mastering the reason why we have those fun toys. I remember taking Firefighter II at Sinclair Community College in Dayton, OH, and spending most of my physical strength and a good couple hours wailing away at cars with hand tools. It was a good exercise, it reinforced the reason WHY we have hydraulic tools, but also WHAT to do if those tools should fail. The same is true in EMS, we want to get that intubation, but forget that an OPA or NPA is almost just as effective in most cases.
In keeping with the back to basics theme, I've done ventilation already, but neglected to tell you WHY we do ventilation in the first place. Such a concept is not easily grasped without a firm understanding of how fire behaves. This will be a two part episode, as the concepts are complex but easy to understand when presented correctly. Without all the background in an IFSTA manual, I will define and explain fire behavior in a manner that should be easily understandable. You should refer to Essentials of Firefighting 5th Edition for a brisk review should you need one.
So what is fire? Simply, fire is the result of a chemical reaction involving fuel and an oxidizer which on Earth is typically oxygen, although some other oxidizers exist. This process is called cumbustion. In order for it to be called fire, light and heat must be produced, although the creation of a flame is not always present. Typically a fire will involve hydrocarbon fuels.Remembering the Law of Conservation of Mass and Energy, matter can be neither created nor destroyed. As a result of the chemical reaction involved in combustion, the fuel changes to energy.
The fire triangle is often used to describe the combustion process, using the elements that are necessary for a fire to sustain itself. Fire is sustained when oxygen mixes with fuel, and heat creates fuel vaporization in order to burn. A common misconception is that the fire burns the matter as it is. Vaporization is when the heat vaporizes the fuel into a gas in order to burn. This is called pyrolysis, and that is where you get the fuel mix, in a space called the reaction zone. Take an ordinary candle flame. If you view the flame from the side you will notice that the flame does not actually touch the wick, this is because the heat is vaporizing the fuel (wax, a hydrocarbon) and as it travels up due to buoyancy into the reaction zone it burns. This is the "hot air rises, cool air descends" effect, because hotter gases have less density in air and are therefore lighter.
Now as the energy is generated it has to go somewhere, right? We are considering the idea of heat transfer. As you know, if you place your hand on a cold object it will get warm. This is called conduction, because the less dense molecules of your hand are flowing to an area of more dense molecules in an attempt to achieve equilibrium. This same concept can propagate a fire in the same manner. As heat flows along a steel beam, for example, it will absorb the heat being transmitted to it as will any other object that is touching the beam. Once the other mass reaches ignition temperature (the amount of energy it takes for the matter to auto-ignite), it will start a fire.
The process where the steel beam is heated by hot air is called convention. It works like your oven. The gas (air) in the oven is superheated, causing the air to move (because of buoyancy, more on this concept later) and transferred through the gas to a solid. Eventually the solid will reach the same temperature as the gas. This is useful to know when using a thermal imaging camera, because the thermal conductivity of all materials are different, and the camera is sensing the temperature differences. You can use this to discern a human body from a lamp, or a couch from a table, etc.
Radiation is a concept that it somewhat difficult to explain. Heat not only travels through solids or gases but also through the electromagnetic spectrum as well. You're thinking "this sounds like convection." And you would be correct, partially. Radiation is the travel of charged particles from a point to another point in space in a direction other than up, although it is included. Think X-Ray. If you emit charged particles upon a target it will warm a little, considering the source, distance, medium of travel, etc. Take a building fire for example. When the heat travels through space and heats the side of an adjacent structure (called an exposure, for those not knowing the lingo) that's radiated heat.
Now that we know how heat is transfered, we can talk about phases of fire. There are five, and they can be expressed as a graph that ties heat release, fire growth, and time together which you will see in a minute. The first phase is the ignition or incipient phase. At this phase, the fire is relatively small and the heat release rate is small as well, but it is steady. From here, the fire can go in two different directions. If the heat release is too small, the fire will fail to grow and smolder out. If the heat release rate is enough to radiate to other fuels and ignite them, the fire goes into a growth phase.
During the growth phase, the heat release rate grows and the fire spreads to consume other fuels around it. If the fire is contained inside a container (a structure in our case) you will get radiation feedback, meaning that the heat from other fire sources is radiating back upon other fuels that are not ignited. This is a dangerous situation and left unchecked will progress to the most dangerous phase of fire growth: flashover.
Flashover. The very sound of it strikes fear into the hearts of even the most stout firefighter. It is unsurvivable for both firefighters and victims. It is the very moment that the radiation feedback loop created by the fire in an enclosed space simultaneously ignites all the contents of the space. This is the transition period into the fire stage known as free burning. Free burning, or fully developed, simply means that the fire is now at it's maximum heat release and consuming all the fuel it can. At this point the fire is only limited in two ways. Fuel limited means that the fire can only consume the fuel available to it, this is typically true for compartment fires. Ventilation limited means that there is enough fuel available but not enough oxygen available to support combustion. This is true for enclosed spaces. In the video you will see the phases of fire, and note what happens just before flashover, you will see off-gassing of vapor from fuel at floor level, this is truly an excellent video if you want to see how fire works. You can find more at NIST's Building and Fire Research Laboratory.
In decay, the heat release rate drops off, and the flames diminish in size. This is caused by the limiting factors above. At this point the fire is at a point that is unable to sustain combustion unless one of the limiting factors is relieved (addition of more fuel or increase in oxygen flow) and the fire becomes smoldering, where the heat release or fuel is of too small a size to sustain free burning combustion.
At left is the heat release curve, crudely drawn on Microsoft Paint, but enough to understand the point. You should take note of this, because I will refer to it later when I discuss extinguishment theory.
So by now you are wondering "what does this mean to me??" It means A LOT. The rookie firefighter is done a serious disservice by not being taught how fire works outside of the fire triangle because using a knowledge of fire behavior you can predict how fire will react given certain conditions. Next time we will discuss different types of phenomena at a fire and how you can keep yourself and your crew safe.
Resources
IFSTA. Essentials of Firefighting, 5th edition, 2007.
Quintere, James G. Principles of Fire Behavior, 1997
Kind of got a request via Twitter, and in answering this request I had to break out my old fire behavior books from college.
I'm a big "back to basics" guy, as I think sometimes we focus too much on the advanced stuff rather than mastering the basics. This seems to be true in most aspects of where I work. We want to play with the big toys, which are the most fun, without mastering the reason why we have those fun toys. I remember taking Firefighter II at Sinclair Community College in Dayton, OH, and spending most of my physical strength and a good couple hours wailing away at cars with hand tools. It was a good exercise, it reinforced the reason WHY we have hydraulic tools, but also WHAT to do if those tools should fail. The same is true in EMS, we want to get that intubation, but forget that an OPA or NPA is almost just as effective in most cases.
In keeping with the back to basics theme, I've done ventilation already, but neglected to tell you WHY we do ventilation in the first place. Such a concept is not easily grasped without a firm understanding of how fire behaves. This will be a two part episode, as the concepts are complex but easy to understand when presented correctly. Without all the background in an IFSTA manual, I will define and explain fire behavior in a manner that should be easily understandable. You should refer to Essentials of Firefighting 5th Edition for a brisk review should you need one.
So what is fire? Simply, fire is the result of a chemical reaction involving fuel and an oxidizer which on Earth is typically oxygen, although some other oxidizers exist. This process is called cumbustion. In order for it to be called fire, light and heat must be produced, although the creation of a flame is not always present. Typically a fire will involve hydrocarbon fuels.Remembering the Law of Conservation of Mass and Energy, matter can be neither created nor destroyed. As a result of the chemical reaction involved in combustion, the fuel changes to energy.
Now as the energy is generated it has to go somewhere, right? We are considering the idea of heat transfer. As you know, if you place your hand on a cold object it will get warm. This is called conduction, because the less dense molecules of your hand are flowing to an area of more dense molecules in an attempt to achieve equilibrium. This same concept can propagate a fire in the same manner. As heat flows along a steel beam, for example, it will absorb the heat being transmitted to it as will any other object that is touching the beam. Once the other mass reaches ignition temperature (the amount of energy it takes for the matter to auto-ignite), it will start a fire.
The process where the steel beam is heated by hot air is called convention. It works like your oven. The gas (air) in the oven is superheated, causing the air to move (because of buoyancy, more on this concept later) and transferred through the gas to a solid. Eventually the solid will reach the same temperature as the gas. This is useful to know when using a thermal imaging camera, because the thermal conductivity of all materials are different, and the camera is sensing the temperature differences. You can use this to discern a human body from a lamp, or a couch from a table, etc.
Radiation is a concept that it somewhat difficult to explain. Heat not only travels through solids or gases but also through the electromagnetic spectrum as well. You're thinking "this sounds like convection." And you would be correct, partially. Radiation is the travel of charged particles from a point to another point in space in a direction other than up, although it is included. Think X-Ray. If you emit charged particles upon a target it will warm a little, considering the source, distance, medium of travel, etc. Take a building fire for example. When the heat travels through space and heats the side of an adjacent structure (called an exposure, for those not knowing the lingo) that's radiated heat.
Now that we know how heat is transfered, we can talk about phases of fire. There are five, and they can be expressed as a graph that ties heat release, fire growth, and time together which you will see in a minute. The first phase is the ignition or incipient phase. At this phase, the fire is relatively small and the heat release rate is small as well, but it is steady. From here, the fire can go in two different directions. If the heat release is too small, the fire will fail to grow and smolder out. If the heat release rate is enough to radiate to other fuels and ignite them, the fire goes into a growth phase.
During the growth phase, the heat release rate grows and the fire spreads to consume other fuels around it. If the fire is contained inside a container (a structure in our case) you will get radiation feedback, meaning that the heat from other fire sources is radiating back upon other fuels that are not ignited. This is a dangerous situation and left unchecked will progress to the most dangerous phase of fire growth: flashover.
Flashover. The very sound of it strikes fear into the hearts of even the most stout firefighter. It is unsurvivable for both firefighters and victims. It is the very moment that the radiation feedback loop created by the fire in an enclosed space simultaneously ignites all the contents of the space. This is the transition period into the fire stage known as free burning. Free burning, or fully developed, simply means that the fire is now at it's maximum heat release and consuming all the fuel it can. At this point the fire is only limited in two ways. Fuel limited means that the fire can only consume the fuel available to it, this is typically true for compartment fires. Ventilation limited means that there is enough fuel available but not enough oxygen available to support combustion. This is true for enclosed spaces. In the video you will see the phases of fire, and note what happens just before flashover, you will see off-gassing of vapor from fuel at floor level, this is truly an excellent video if you want to see how fire works. You can find more at NIST's Building and Fire Research Laboratory.
At left is the heat release curve, crudely drawn on Microsoft Paint, but enough to understand the point. You should take note of this, because I will refer to it later when I discuss extinguishment theory.
So by now you are wondering "what does this mean to me??" It means A LOT. The rookie firefighter is done a serious disservice by not being taught how fire works outside of the fire triangle because using a knowledge of fire behavior you can predict how fire will react given certain conditions. Next time we will discuss different types of phenomena at a fire and how you can keep yourself and your crew safe.
Resources
IFSTA. Essentials of Firefighting, 5th edition, 2007.
Quintere, James G. Principles of Fire Behavior, 1997
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