Le feu face aux pompiers ! - C'est pas sorcier [Intégrale]

In France, a fire breaks out every two minutes. On average, the fire kills 10,000 people each year, and kills 800 people. To understand the fire and its dangers, Fred is going to follow a training session close to the flames with the firefighters. Jamy, meanwhile, has set up his lab at the CNPP, a unique centre in Europe specialised in fire prevention and risk management. Today, we're going to find out how firefighters fight fires, that fumes are often more dangerous than flames, that water is not always the best weapon to put out a fire, and that the biggest danger for firefighters is widespread combustion and the explosion of fumes. Let's go, Jamy, let's go, because training or not, it's a big fire waiting for us. What state of mind are we in when we set off on a fire like this? We have a small amount of adrenaline, which is quite logical, especially on denunciation with victims. So the goal for us is to control that. That's what we call a good stress. You're a professional, Julien, I think. Yes, I'm a professional, that's it. You're a professional, but both of you are volunteer firefighters. How do you become a volunteer firefighter? So you have to pass recruitment tests to see if you have a good physical condition, and then find your motivation to integrate the firefighter corps. How did it go the first time you were confronted with a fire? It went relatively well, because it wasn't very violent, it was a car fire, and it allows you to get in the bath nicely. And volunteer firefighter, that means you have a job next door, of course, but you intervene as a firefighter every how many days? At home, it's a guard every six days. A guard every six days. So we're going to do the binomial on the fire, right? I'm not leaving you, I'm staying with you. We're going to do the binomial on the fire. Binomial on the fire, what does that mean? It means we're going to be the spear, we're going to attack the fire. It means we're going to be in contact with the fire? Yes. Well, I feel like the adrenaline is going up a bit. It's going to be fine. It's hot, isn't it? So to talk about fire, today I'm sitting in a fire hall, all blackened by the experiments we do there. A few numbers to start with. In France, there are 250,000 firefighters, most of whom are volunteers. That said, regardless of their status, volunteers or professionals, they all fight the fire in the front line. Firefighters who intervene very quickly on the spot. Indeed, they do their best to intervene in less than 10 minutes when the fire breaks out in the city, and less than 20 minutes when it breaks out in the countryside. Not bad, huh? So, Fred, where are we? I think we're almost there, Jamy. In any case, I can tell you that it didn't take long. What does that tell you, guys? We can see the flames, we can see the smoke, so we know it's a real fire. But it's burning well, isn't it? It's burning well. We can confirm that it's burning well. What, is it coming out through the windows? We're going to come get you, don't worry. A priori, we are facing a fire on the first floor of an R2 building. There is a victim, a priori, who is manifesting. You, Sébastien, you proceed with the rescue of the victim, and then we will engage reconnaissance. Come on, let's go, guys, let's go. OK. If there is too much smoke, you move back. Let's go. Yeah, perfect, it's strong enough. It's good, it's good. You take your connection and you present it to the driver. OK. Is it good, Fred? Yeah, it's good. OK, Fred. OK. It's going well. So now we're protecting the passage, OK, Fred? The rescue is the priority, it's an immediate reaction. OK. Then we try to limit the spread to the rest of the building. OK. The victims first. You should know that a fire does not occur under any circumstances. Three elements must be brought together. First, you need a fuel. So when we talk about fuel, we think first of gasoline or alcohol, or even wood or paper. But the fan can be much wider. It can be a chair, a carpet, a pair of curtains. In short, everything that burns. Then you need a source of heat. A badly crushed cigarette, a ember that has caught fire, a spark produced by a short-circuit. But here too, we can have surprises. It can be a wire that heats up because we plugged too many devices into the same socket. Finally, you need oxygen. The oxygen contained in the air is what we call the conductor. When these three elements are brought together, the fire can start. This is what we commonly call the fire triangle. To control a fire, you have to remove one of these three elements. Removing oxygen, for example, is what we do when we cover the flame with a candle. The air quickly goes out, and the flame goes out. I remind you that this is a violent apartment fire. It's been going on for a while. We evacuated the person at the second level. Now we're going to proceed with the extinction. Be careful, I think the level of heat is relatively high. So don't forget all the temperature tests you have to do. OK, guys? OK. Come on, let's go. You're going to warm up before you go in, OK? Come on. OK. Put on your micro-regulator. I'll help you. OK? Everything is OK? We're going to try to get into this building and find the firehouse. Come on, let's go, guys. Close the door, let's go. Normally, it's a big volume. It doesn't evaporate, it goes down in droplets. The door is not hot, we can get in there. OK. Does that mean we can go in there? You stay right in the middle. Stay behind you. Yes. Follow the pipe, Val. OK. OK, it's good, guys. You can go in. You go straight ahead, the room is on the right. Don't worry. Anyway, we don't have a choice. We're tied up. So we're equipped with ventilators. They are insulating respiratory devices that protect us from toxic gases and smoke. They are absolutely essential. Otherwise, we won't be able to progress on these devices. We're going to test the door in front of us. OK. It evaporates on the door. Does that mean it's hot? I'm going to open the door and do a ceiling test. Wow! We're going to get a big hot meal. It burns well. It doesn't evaporate. It goes down in droplets. We can get in a little bit. OK. I'm giving impulses to the ceiling to inertate, that is, to prevent hot gases. So it forms lots of small droplets. And what does that do? It cools the atmosphere, right? The large contact surface with hot air is what cools the atmosphere. Why spray water in the form of droplets? Well, simply because in this form, it evaporates more easily than in the form of gasses. What's the point, you might ask? Well, to go from a liquid state to a steam state, water needs energy, energy that it will draw in the form of heat. As a result, the temperature inside the premises where firefighters intervene will considerably decrease. But that's not all. This steam has another effect. In this form, in the form of steam, water occupies a larger volume than in a liquid state. For your information, when you heat a liter of water to 100 degrees and all the water evaporates, well, the steam occupies a volume of 1,700 liters. As a result, the steam will chase the air, take its place, and as a result, the fire will be deprived of oxygen, one of its vital elements. Here, let's do a little experiment that illustrates this phenomenon well. When I crack a match, and I keep it in the open air, you see, it burns without any difficulty. If now I immerse it in water steam, after one or two seconds, it suffocates. So you might think it's because of the humidity, not at all. It's because the water steam takes the place of the air and deprives the flame of oxygen. And now, you're not going to move anymore? We're going to move straight, we're going to move the boat with a small amount of water. It's the big droplets, it's going to drown the embers and it's going to end the fire. Okay. Are you okay, guys? Okay, did you feel a little hot? Yeah, I understand that there is really a technique to extinguish a fire. You know, it's a technique, you can't improvise. Contrary to what one might think, smoke makes more victims than flames. A figure, 80% of deaths are due to an intoxication or an asphyxiation caused by smoke. It's true that smoke is really the trap for firefighters, not only because they are toxic, but on top of that, they prevent absolute visibility. That's why firefighters are trained to move in confined environments like this. So we can see that the smoke is rising, by the way. Yes, the effect of hot gases is always stratified on the ceiling and when it gets intense, it always ends up going down a little more. So you always have to walk as low as possible. The lowest, that's a rule. We stay as close as possible to the ground. So what is the behavior to take if a fire breaks out in your home? In an individual house, you have to confine the fire, that is, close the door of the room in which it broke out We don't try to put out the fire. No, it's often too late. On the other hand, when it happens in a building, if it's above your apartment, you can evacuate by the nearest emergency exit. If it's at the same level or below, you must not go out. It's exposing yourself to toxic gases and that's terrible. You have to stay at home, lock the door with damp towels, it is designed to resist fire for a while, and report its presence to the emergency by the windows. But above all, don't go out in the smoke, it's really too dangerous. Absolutely not. We said it, the smoke makes more victims than the flames. In fact, two-thirds of the victims die at night during their sleep. They are suffocated or intoxicated without waking up. So to reduce the number of victims, all the homes will have to be equipped with smoke detectors, DAFs, as they say in the jargon. We're going to see what this one has inside. It smells a little burnt. It's normal. We are here in a laboratory, a room, in which we test the smoke detectors. So, a smoke detector is equipped with an electroluminescent diode, which is commonly called an LED. This diode constantly emits infrared rays. And then, right next to it, there is a photoelectric cell. It's this cell that triggers the alarm. Normally, as you can see, the infrared rays don't reach the photoelectric cell. Now, a fire starts. The smoke rises. It penetrates inside the smoke detector. The particles that make up this smoke will scatter the light. And as you can see, only a part of the rays will be deflected and reach the photoelectric cell. The more smoke there is, the denser it is, the more the rays reach the photoelectric cell. Well, from a certain density of smoke, the cell receives enough light, enough energy to produce an electric current that triggers the alarm. Well, now, we're going to test the smoke detectors that are suspended on the ceiling. Today, these alarms begin to be installed in homes. But from March 2015, they will be mandatory in all homes. And in the meantime, here at the CNPP, they are subjected to a whole battery of tests to measure their reliability. Heat resistance, shock resistance, sensitivity to electromagnetic waves. We're ready. So, contrary to what we might imagine, water is not always the best way to extinguish certain fires, in particular hydrocarbon fires. We're going to do a little experiment with water, precisely. Shall I go there? Let's go. Come on. Hop. There. So, what's going on? In fact, hydrocarbon is lighter than water, isn't it? Indeed, it will overflow and the risk is that it spreads and propagates the fire much further. OK. if it was effective. No, not at all because it continues to burn. Come on, let's give up water. We're going to take another way. Hop. Fred? Yes? I think you're going to need this tool. OK? OK. We're going to use foam. What is foam? It's a mixture of water. It's emulsifier, water and then air. OK. So, the advantage of foam is that it will form a kind of carpet. It will isolate the fuel that burns from the ambient air and if there is no more air, well, obviously, the fire goes out. Is that the principle? That's it, exactly. That's what you use in particular on refinery fires, for example. Yes. Wow, we're really close. No, no, it's good, it's good. Don't worry. So, on hydrocarbons, Jamy, preferably, we use foam. Indeed, it's much more effective. So, we're going to do another experiment. This time, we're not going to use hydrocarbons, but cooking oil, vegetable oil. So, this is the situation that we've tried to reproduce. You're at home, in the kitchen, preparing a meal. You're going to pour oil into a container that you've set on fire. Only, for some reason, you forget this container on the fire. The problem is that after twenty, thirty minutes, the oil will spontaneously ignite. That's it. So, the oil is on fire. in general, when we're faced with this situation, it's a bit of a panic. We see flames. Right away, we think of water. So, we grab the first container that comes, a glass or a cup, for example. We fill it with water and we throw it on the flames. Before doing this exercise, I'm going to take one last precaution. I put on a helmet. So, we take the container and we throw it on the flames. Wow! Obviously, it's not the result we wanted to get. And in a kitchen, it can cause a lot of damage. Everything happened very quickly. So, to better understand the phenomenon, we're going to break things down. What happened? Well, the water, being denser than the oil, it flows to the bottom of the coconut at the contact of the heat. It instantly turns into steam and forms bubbles that will rise and burst by throwing a multitude of small drops of oil all around the container. So, we end up with a larger amount of oil in contact with the flame. This is what will cause the fire. Wow! As a result, to put out this type of domestic fire, we don't use water, but an utensil that is also present in a kitchen, a kettle, or a large torch. Is that right, Pascal? Yes, absolutely, Jamy. First of all, we're going to close the gas bottle. Yes. So, use a bucket with water. Put a teapot in the bucket. Yes, why do you have to soak the teapot? To inflate the fibers, Jamy. Yes, why? To make it the most waterproof in the air. Okay, you also have to wring it out to avoid putting water in it. We saw what it looked like before. Here, the goal is to put your thumbs on the outside, to protect your hands from the heat. Always with your arms stretched out, always keeping a safe distance with your face. Okay. And here, I'm going to cover the teapot quietly. Okay. And you know, Jamy, the principle of the torch also works with a car. Are you ready? Let's go. The visor. Be careful. A lot of smoke. Don't touch the body, I think. There's pressure. Are you okay, Fred? I'm okay. Okay. But it's out of the question to do it yourself. Watch your foot on it, Fred. Don't let it fly away. Are you okay, Fred? I'm okay. What firefighters are most likely to do when they intervene in a fire is the generalized what we call the flash over. So, to teach them to detect this risk, well, we're going to put them in this box. And in this box, Gilles, we're going to set it on fire, right? That's right, Fred. In this box, we're going to set it on fire so that we can show the trainees all the signs of fire up to the precursor of the flash over. And to do that, we use fuel, mainly fuel that can be found in everyday life, that is, in housing, in public buildings or in industry. Okay. Let's go. I think it's very spectacular. The exercise is in real fire and in a warm atmosphere. The trainees will comply with the instructors' directives. Everyone must feel fit to follow the exercise. The trainees have hydrated before accessing the simulator. Is that right? 1, 2, 3. First trainee, Okay, I'm going. Let's go. It's a funny feeling to lock yourself in a box like this and set it on fire. It's true that it's quite strange. Just above you, the stratification of the smoke layers. For those of the first row, we begin to feel the heat by radiation. Yes, I confirm that. We feel the clothes that are heating up very clearly. Flames begin to come out of the fire zone and we should soon be able to see the first dancers' ankles. Shut up. The fire is completely above us. Look, Fred, at the top left. Oh yes, okay. The dancers' ankles. It's a nice name but it's really very impressive. These pockets of gas that ignite and reach each other furtively. Right behind the flame rollers that are called rollovers, there are smokes that burn. The smokes burn, gentlemen. Look, raise your head. The smokes burn. I've never seen that before. Very impressive. Everything is on fire. And it's very hot too. We're right in the middle of the fire. It's hot. How are you? It's hot, isn't it? Thanks to this kind of exercise, today we can put out the fire differently than before. Indeed, we put out the fire differently because our problems have evolved. A few decades ago, the buildings were not as well insulated because they were less well insulated. The temperatures that we could reach in the buildings were less high so we didn't see the phenomena that we see today because of the much higher temperatures that are reached. OK. In particular, the smokes that burn, we had to reach at least 500-600 degrees. These are temperatures that we didn't reach when our buildings were less well insulated. Here are images that show how dangerous these smokes can be. They were filmed during the fire on a large surface in Lima, the capital of Peru. The fire was declared at the second or third level of the building and as you can see, at first, the smokes accumulate at the last level of this building. They become more and more dense and also more and more hot. Moreover, at this temperature, they could ignite but for the moment they lack air, they lack oxygen, one of the essential elements of the fire triangle until the moment when other firefighters will create a breach on the other side which will cause an arrival of air and trigger an explosion of smoke. So I reassure you right now, the firefighters that you see on the ground got out of it with a big fright, most certainly, but fortunately they got out of it. That's it, Fred? Did you finish your training? Not quite, Jamy. I just have a very small thing to extinguish. A helicopter. Fred, you will be an attack pilot. You take the equipment to establish a foam launch. Attack point here, takeoff used, launch the pump. Well, it didn't go in. Come on, set it up, it's burning!