Fire Science Show
Fire Science Show
208 - The basics of fire water supply with Szymon Kokot
Water might seem like the simplest part of firefighting – just point and spray, right? Well, as you can imagine, the reality is a bit more complex. In this conversation with veteran firefighter and CFBT instructor Szymon Kokot, we pull back the curtain on firefighting's most critical resource to reveal the intricate science and logistics behind effective fire suppression.
Did you know a standard fire truck carries just 10 minutes' worth of water for a typical residential fire? Or that a water-filled fire hose can weigh up to 45 kilograms per 20-meter section? These physical realities shape every aspect of firefighting operations and explain why building water supply systems are absolutely vital for effective emergency response.
Szymon walks us through essential concepts that every fire engineer should understand – from critical flow rates (2 liters per minute per square meter of fire area) to tactical flow rates (4 liters per minute per square meter) that provide both effectiveness and safety margin. We explore how water's cooling capacity works primarily during evaporation, why cooling burning materials is more important than extinguishing visible flames, and how different water application techniques serve different tactical purposes.
The conversation demystifies hydrants versus standpipes, dry versus wet systems, and the specialised requirements for different building types – especially the unique challenges of high-rise structures where external water supply is virtually impossible. We also confront the all-too-common reliability issues that plague these systems, from maintenance problems to vandalism.
Whether you're a fire engineer looking to design more effective systems, a firefighter interested in the science behind your craft, or simply curious about this intersection of physics, engineering and emergency operations, this episode delivers valuable insights into how water – our oldest firefighting tool – continues to shape modern fire safety design and operations.
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Hello everybody, welcome to the Fire Science Show.
Speaker 1:When I told you before that if you want to know what firefighters want from your fire engineering and how can you support firefighters and their operations with your fire engineering, the best way is to ask a firefighter. And that's what I'm trying to do today. In this episode I have invited once again my firefighting friend, shimon Kokot. Shimon is a local or perhaps even a global legend of combatant fire behavior training and he is my go-to person to consult the matters of the interface between fire safety engineering and firefighting. And when I was thinking about the topics or questions that I could ask the Shimon, one was very obvious to me and that is the water supply. I had privilege to learn a lot about the water supply because I was doing my master's at a fire academy where we learned it alongside the firefighters. So actually I had enough luck to learn this as a firefighter would. But I have a feeling a lot of us fire safety engineers do not have in-depth understanding of how water supply works in case of a fire, how impactful it is for firefighting. It's obvious it's impactful, but exactly how does it work and how we as fire engineers can support our firefighting colleagues by designing better water supply systems for the buildings. So in this podcast episode, water Supply 101 with firefighting instructor Szymon Kokot, let's spin the intro and jump into the episode.
Speaker 1:Welcome to the Firesize Show. My name is Wojciech Wigrzyński and I will be your host. The Firesize Show is into its third year of continued support from its sponsor, ofar Consultants, who are an independent, multi-award-winning fire engineering consultancy with a reputation for delivering innovative, safety-driven solutions. As the UK-leading independent fire risk consultancy, ofar's globally established team have developed a reputation for pre-eminent fire engineering expertise, with colleagues working across the world to help protect people, property and the planet. Established in the UK in 2016 as a startup business by two highly experienced fire engineering consultants, the business continues to grow at a phenomenal rate, with offices across the country in eight locations, from Edinburgh to Bath, and plans for future expansions. If you're keen to find out more or join OFR Consultants during this exciting period of growth, visit their website at ofrconsultantscom.
Speaker 1:And now back to the episode. Hello everybody, welcome to the Fire Science Show. I am joined today by my good friend, szymon Kokot. Hey Szymon, hi Wojciech and hello everyone. Good to have you back in the podcast and very glad that you took my invite for this non-trivial episode. The reason I brought you here some weeks ago I recorded a podcast episode about fire safety engineering with firefighters in mind, and, of course, the first thing I said in that episode if you want to know what firefighters want, talk to them. Therefore, here we are you are my firefighter of choice. But the second thing was I was contemplating what is something that could be very important to firefighters that we fire engineers do not really appreciate or have not had a chance to really learn, and then it struck me that it could be water.
Speaker 1:So let's have a wet episode of Fire Science Show and I hope you will tell me all the interesting stuff about how you use water, why you need water and how it works in firefighting. I'll try to do my best, of course. Yeah, so what are you using water for in the firefighting?
Speaker 2:job. Yeah, so Physics 101, I guess everybody knows. I assume that everybody listening to your show should know that if we use water, we use it for cooling. A fire is a phenomenon that produces heat. Therefore, one way of combating it is to cool it down below a certain point in which the fire propagation is no longer possible. So we of course, use the cooling capacity of water. Now, as firefighters fire engineers, educated firefighters we know that water takes the most, the biggest amount of heat when it evaporates. So we will try to use water in a way so that it turns into steam and by using the characteristic called the latent heat of evaporation or phase change, we take probably six times as much heat as it is necessary for the water to be heated from the average 15 or 18 degrees to 100 when it evaporates. So yeah, so that will be our main goal. To use water is to cool down to extinguish. Then, when we produce steam, we also dilute the oxygen and therefore it's another joint mechanism of extinguishing.
Speaker 1:By cooling? Is it primarily cooling the hot gases products or?
Speaker 2:you care also about cooling the structure itself, like the walls and other elements work.
Speaker 2:That was for me very instrumental in understanding that we may combat the gases which are the effect of the phenomena that are occurring inside the compartment, but it's because of the heat stored in the solids by conduction is why these solids are thermally decomposing and producing gases.
Speaker 2:Therefore, the larger part we say like the two-thirds of the cooling capacities is actually necessary in the fuels to extract the heat from them and stop producing flammable gases. And therefore, by understanding this, of course, we will combat any threat from the flammability of gases. When we travel to the seat of the fire, when we dive into the smoke, we want to cool and dilute the atmosphere so that we have a safe journey, let's say, so that we cool the gases so they don't ignite but also they don't carry the heat behind our back, to heat the fuel behind our backs. And by doing this we limit the possibility of having, let's say, an escape route cut off. But the goal is to travel to the seat of the fire and put the water on the burning fuel so that it stops producing smoke but also heat, because it's a self-propelling mechanism, as everybody probably is well aware of.
Speaker 1:So if you had a fully developed fire, a flash-over fire, you come in, you spray, disperse water spray. I guess it's, let's say, easy I'm not sure you can call it easy, but easy to put down the flames down, but if you stop applying water at that point, it all evaporates. You did not, you did not take away the heat from the structure yeah, so it may just well reignite very soon.
Speaker 2:Yeah it's it's. There's a couple of mechanisms combined here, but first of all we always teach because I'm also an instructor for cfbt compartment, fire behavior training. We teach that gas cooling, as it is originally called by the Swedes and then applied globally, gas cooling is not an extinguishing technique. It's a technique to secure your passage to a place where you can effectively extinguish. So it has a specific goal, it has a specific way of application and so on.
Speaker 2:We will rather normally in European countries where we use sprays because we need to conserve water more and we are, generally speaking I hope nobody will be offended by this but generally speaking we are less aggressive in our approach to interior firefighting compared to our American colleagues who use a smooth board which don't have such possibility to disperse water into fog.
Speaker 2:There is a possibility, of course, by halfway opening of the bale or rapid movements in the inverted U or O pattern and so on, to create some droplets. They will rather focus on cooling different surfaces and producing steam. There isn't a lot of steam produced in this way, but when we use sprays we rather avoid applying water to the structure, especially the ceiling, because of the amount of heat generated will turn everything into steam and if we don't cool the gases, the gases will not contract. If we evaporate the water on the ceiling, it will produce steam but will not contract the gases. Still, in 100 degrees Celsius, water turns into steam in the ratio of 1 to 1 to 1700. In 200 degrees is 1 to 2100 or 2600, and so on and so on. It just according to Clapeyron's rule. The same amount of water will produce more volume of steam if it's heated to a larger temperature yeah.
Speaker 2:Yeah, so we must avoid what we call the water trap or the steam trap With this method of application. This is a concern, so yeah. So then we travel and then when we see, or maybe have an idea that this might be the room of origin, well, normally we can't see anything. But let's say, we use the thermal imaging camera and we see that there's a piece of furniture burning in the corner. So we switch to our solid stream, we make use of the reach of the stream and we direct water to the seat of the fire and then therefore stop production of heat fantastic.
Speaker 1:So we're just a few minutes into the podcast, but I've already learned something new and I think a lot of listeners already learned something new that there is way, way more science into spraying water on stuff than you would think after watching a few of Hollywood movies. Okay, this is brilliant because there's a lot of choices and, of course, this means having a quick access to water is something that's absolutely critical for you. Um, another question, and I I guess this goes also back to to paul greenwood's research how much water do you actually need to to take down the fire?
Speaker 2:yeah, well, it depends, as professor spenson often says, but you know you can never answer. It depends, and be happy with yourself, because then you have to expect. I mean come on.
Speaker 1:Yeah, five buckets is not enough, and uh, and an air tanker is probably too much so.
Speaker 2:look, we approach firefighting just like, I guess, the engineering world in a in a manner that takes into consideration the factor of time. Yeah, because if the heat is produced over time, so joules over seconds, giving us watts, we also apply water over time. Therefore, when we say about flow rate, we say, let's say, 100 liters per minute, or gallons, or whatever.
Speaker 1:We say liters in this podcast, please, Okay, yeah, okay, I will.
Speaker 2:I will, but I already gave praise to the American firefighters. They do fight more aggressively. Perhaps that's why they have to use gallons instead of liters, that's also true, but they have more lightweight constructions, they have bigger roads, bigger trucks, and it's just another reality. So we don, and it's just another reality. So, we don't really want to compare anything.
Speaker 1:Yeah, but Prince was trying to say which is better or worse. No, no, of course not.
Speaker 2:But okay. So the late Paul Greenwood. In his early work, I guess around 90s I think his book Fog Attack was published in 1990 or 91. He referred to something that was called critical, tactical and optimal flow rates. This applies to residential areas. We differentiate this from industrial area basically because of the fact of the height of the ceiling and normally larger floor plans, resulting in a bigger volume. Therefore, in a bigger volume, the dynamics of the development of fire may differ from the smaller room, as you probably mentioned already a couple hundred times in your over 200 episodes.
Speaker 2:When there's a flashover it's like a game over for this compartment. But not every compartment has the ability to flashover. Basically, first of all because of the geometrical aspects and secondly, if there's not enough air it will suffocate. If there's not enough air, it will suffocate. So for residential, we can say that there is probably a limit or a spectrum of limit of the heat release rate, peak heat release rate that can be achieved by this particular compartment. Let's say we are now in a room that has, like what, four by three meters and probably two and a half to the ceiling. So you know as much as you can put stuff here, the the size of this door will will dictate the the piece release rate. So let's say it will be like let's give it four. Yeah, let's ask. I was gonna say let's give it a good six or seven. Yeah, it's also possible.
Speaker 2:Well, normally, if you calculate the number of the amount of heat you can take away, if you use one liter of water, it will be enough to combat, I think, 2.5 or 3 joules. If you apply this over a second, then you will use kilojoules, no megajoules, megajoules, of course, of course. Yeah, yeah, thank you for correcting me, but you can almost never use one liter of water perfectly. So this was actually the work that Paul Greenwood did in his doctoral thesis, where he applied different factors to understanding one word used in a British legislation which is adequate, what is adequate water supply? And it's interesting how one word can mean a vast reality of knowledge which is sufficient to write a doctorate and probably not even one doctorate.
Speaker 2:And the revolution yeah exactly, and so he came up with different formulas. But starting with his earlier formulas, let's say if we have what will be easy to calculate a 50 square meter flat that is fully developed fire. So there's fire everywhere. Every square meter is on fire and the flames are shooting out of every window, so there's enough surface for exchange of gases hot gas going out, well ventilated.
Speaker 1:It's Well-ventilated yeah.
Speaker 2:It's still under-ventilated in a way, because this fire could consume more air, just if it had the possibility. But by this let's say it's 50 meters of fully developed fire. If we apply two liters per minute per square meter we can probably start to be effective against combating this fire. So two liters per minute times 50 meters is 100 liters per minute. It's not a lot in firefighting reality, but we must take into consideration that this is a compartmentalized area, so we cannot apply with one nozzle this 100 liters to every you know square meter of this area.
Speaker 2:So there comes different factors into play. If, for the same fire, we apply 4 liters per minute, that gives us the result of a necessary flow rate of 200 liters per minute, we will have a tactical flow rate, which means that we will be already well protected and have good efficiency of extinguishing.
Speaker 1:So kind of what is necessary, plus all the margins of safety that you would apply yeah, yeah. Allowing you to be less efficient in the application, perhaps. Yeah, yeah yeah.
Speaker 2:Then he said something like 1.86, if I remember correctly. Therefore, for easier calculation, two liters per minute. You cannot go below that and hope that you will be effective below that and hope that you will be effective. If you aim at four, then you are both effective and have good protection for your firefighter, because then you have to put a human being inside or close to it. Then it's not fun.
Speaker 2:But this is for residential. For residential, yes, for residential. But then if you move to six, so that gives you 300 liters per minute, then there is no more gain in efficiency, but then you'll start losing water and it will be turned into water damage rather than efficiency of extinguishing. And then it's a simple formula. Now, if you take five as a factor, which is between four and six, that gives you easy calculation, because whatever is your area, you divide it by two and you add one zero. It's a very simple way of calculating. But then let's say, if you want to extinguish a residential fire, you don't have to really go into all these calculations. You can be based on your experience and also keep in mind that you have a 500 liters per minute nozzle, so that should give you a decent 250 square meters of area fully engulfed that you should be able to extinguish with this, provided that you can apply water perfectly.
Speaker 1:So that's one stream of water could be 500 liters per minute.
Speaker 2:Yes, or four or five, depending, but normally the nozzles apply this kind of flow rate. But then, okay, first of all you're not able to apply this to the whole surface, so you have to give more nozzles, and more nozzles means more time of preparing, more equipment, more people. Then, if there isn't discipline and there isn't knowledge in your team, everybody will turn to full power and then after four minutes you're empty with one tanker. Now comes into play your water source. Water supply, you know. But here you can see how very important and crucial is education, because they will not achieve more efficiency by standing in this one place and giving your full power inside, let's say, through a window, or maybe they are trying to already approach the door or whatever. So there's this whole education and then tactical game that you have to play.
Speaker 1:In terms of the timeframes. How long does it take? How long does the structural cooling take? Actually? Like do you plan this for? I don't know? Five minutes for an hour, for more than an hour? I assume you also probably would reduce the amount of water you use for the cooling phase the cooling of the structure. Yeah, yeah, yeah, you mean like the… you came in, you took the flaming combustion out, but your structure is superheated. So let's say this 50 square meter room, but do you mean combustibles or construction elements.
Speaker 2:Well, I guess you have to cool all of them. Yeah, but some of them with water, so you don't have the re-ignition. But if you have heat in your concrete walls, you just open the windows and let it cool down.
Speaker 1:It's not a threat, okay, okay, so for combustibles, I guess, how long would it take?
Speaker 2:So in that case, not that very long. No, no, I mean as long as it first of all releases gases, which means that it has, on average, more than 200 degrees Celsius of temperature. Then it continues to produce steam, so it's over 100. But if it's over 100 and it produces steam, theoretically you don't have really a good way of stating this. So as long as you can see some vapor, you continue to fight the problem. But from some moment it's not pyrolysis anymore, it's just evaporation. It's not pyrolysis anymore, it's just evaporation, and there's over 100 degree Celsius difference between those two thresholds.
Speaker 1:Do you and your colleagues already have some expertise in applying those rules for full exposed timber compartments like mass timber?
Speaker 2:I don't have such experience, and it's still rare experience in many people because of the relatively low frequency of occurring of these structures and them catching fire.
Speaker 1:I mean it's another obvious thing for mass timber that is going to participate in the fire, so therefore your consideration does it burn or not is gone because all surfaces would burn.
Speaker 2:I mean, I mean, look from a perspective of a firefighter, is is something I don't really even want to think about yeah it's just like, uh, you know, lithium-ion batteries or any kinds of new technologies that you know it's, it's nice. I I don't get me wrong, I mean I'm, I'm also a human being. I have a cell phone that uses batteries, a laptop and uh, you know and and you would not mind, living in a nice timber house.
Speaker 2:Yeah, and the cool, how you care about the environments and so on, but I I always say I'm sorry. I'm very straightforward about this. Firefighters are the guinea pigs, the experimental rabbits of any industry that produces anything for the world. You know, because it's being pushed to the market. Then something goes wrong, then we intervene and we are mostly the first ones to find out systemically what the hell is wrong with this or the other technology.
Speaker 1:Okay, I don't want to debate too much to Mustin but, it was just a curiosity, and if I'm curious then there's definitely plenty of listeners who are curious about this as well. In K, let's change the environment from residential. Let's say you're fighting in a shopping mall, perhaps an industrial building, so much larger spaces perhaps is less chance that you'll have an, a flashover in the classical way of understanding flashover, but you may have also many, many hundreds of square meters burning at the same time.
Speaker 2:similar principles apply, like 200 liters per minute, per no no, normally it's way more and it's not and it's not increasing linearly. But you know, you just take another formula and kind of exponentially increase the amount of water you need to apply. Then you also change your methods of application. The thing is that in a residential fire, as we said, there's first of all some limit of the heat that can be generated. It's limited by the geometry. So probably by using walls, hiding behind the walls, getting away from a straight line of radiation and so on getting away from a straight line of radiation and so on, you can. You can try and sneak up on the fire and, you know, apply some water, like maybe bounce it from the ceiling, create this sprinkler effect, or bounce it off the door frame from 10 meters before you actually are at this place.
Speaker 1:I saw those tricks. They're ridiculous.
Speaker 2:And it's not so easy to be applied during a large fire, where you know normally large constructions are also more lightweight. Therefore they are prone to collapse, and there is a certain point which is a gut feeling really at the fire, that you don't commit firefighters inside anymore unless there's obvious signs of people you need to rescue, other than that you don't risk life of your firefighters for rescuing property.
Speaker 1:And car parks, like how much water you need to take down a car or multiple cars so, yeah, so like a car.
Speaker 2:Well, again, it depends on the car parks underground, or or?
Speaker 1:yeah, let's go half open. No, no, no. Well, let's make it difficult underground or very large open plan car parks, like airport car parks yeah, then you.
Speaker 2:Then you enter through a chimney, which is not the pleasure in itself, yeah, you know. But I'd say, look, there are majority of fires, as far as I know, in car parks. They end with a couple of cars being burned, but every now and then all the cars burn like hundreds or thousands of them. We heard about some cases in England, in Norway, I guess, or Sweden, I don't know one of these Scandinavian countries.
Speaker 1:Yeah, in Norway there was Stavanger Airport. Don't know one of these Scandinavian countries. Yeah, in Norway there was Stavanger airport.
Speaker 2:Yeah, near to the airport. Yeah, yeah, but we can also estimate the peak heat release rate and the time of fire for a single vehicle, and then it's probably compared to one compartment in the house. So, if you can really access this car. Well, extinguishing a car is easier, in a way that it burns inside the car, but what's burning it's your seats, it's your rubber, plastic, whatever's inside, unless it's a battery. But then it's another, a little bit of a different situation. But then if the battery burns, really what can you do? First of all, this car is already lost.
Speaker 2:You will not resell it, not even in Poland.
Speaker 1:Well, it sounds like a challenge. Yeah, I'm glad People are saying and they don't try that. Yeah, yeah, let's not give people ideas.
Speaker 2:Don't try that. Yeah, yeah, let's not give people ideas, but let's say I would say, you know, like, if you take what's the English term for this Hose reel, so like a 90 millimeter in Poland or 22 or 25 in different countries Rubber 60 meter long hose line with the Water attached to it.
Speaker 2:Yeah, with high pressure that you can apply. It's normally possible to extinguish one car with this. So sometimes it depends when you see or know there's still cameras working maybe or something and you see it's one car, or you see it just by arriving and you understand it's one car, then well, well, whatever works. If it's more cars, then it's problematic. What is problematic is really the obscured vision, the heat you need to take into your body before you are able to understand where you are, what you are applying water at.
Speaker 1:So again, so in the end we're all again in the region of hundreds of liters per minute.
Speaker 2:Yeah, and you probably can work with that.
Speaker 1:I really wanted to understand the numbers of how much water actually you would need and you come in big red fire trucks. They have their own water supply. That's usually a few cubic meters of water, right.
Speaker 2:Yeah.
Speaker 1:So at like 200 liters per minute.
Speaker 2:So at like 200 liters per minute, 2,000 liters to two and a half is the, let's say, the most popular.
Speaker 1:It's what we call the medium vehicle, so at 200 liters that's 10 maybe minutes of extinguishing action right yes.
Speaker 1:Okay, so it's obviously you need water in the building that the building provides. And here comes the fire engineer, who is right about to design a building, and one of their duties is to design that water supply for firefighting. So perhaps let's talk about different ways of delivering water to the perimeter of the building and to the interior of the building. We call them hydrants, but what kind of the devices are used for that and how much water they actually can get I'm really curious about it.
Speaker 1:Let's say to some extent technicalities, but probably mainly about your experience, experiences in using those devices. Because it's easy. You know, to draw a line right is a pipe. Hundred mil five bars of pressure go, but in reality it verifies the drawing.
Speaker 2:Sometimes very different. Yeah Well, so I'll start by saying that I've been a firefighter for 25 years, so it's a way different story right now than it was 25 years ago. And also, what I can speak about from experience is Poland. But there's so many different countries that have so many different realities, and even you know things like we use a 52 millimeter hand line for interior attack, and the Spain will use 42 or 38, which is more maneuverable but has more pressure loss and applies less water. So probably they can go longer, but they cannot extinguish as efficiently as we do, unless we really waste water.
Speaker 2:So you know, variables can really kill you. But okay, in general. We have a code in Poland that says that there should be a liter per second or a liter and a half per second.
Speaker 1:Which translates to 60-90 liters per minute.
Speaker 2:Yeah.
Speaker 1:My math checks out. Yeah, yeah, I'm good.
Speaker 2:If I'm correct. Yes, Is that correct?
Speaker 1:I think yeah.
Speaker 2:Which is not really a lot of water.
Speaker 1:We're just talking about 200-400.
Speaker 2:Yeah, if you compare that.
Speaker 1:But this is per single line or overall to the building Per hydrant.
Speaker 2:Per hydrant. Okay, now, water cannot be squeezed and water cannot be stretched. It's almost as solid. So I'm saying this to say that if you have a building and it has an external hydrant well, it used to be the case that hydrants were just valves on the ground you have to first prepare the hydrant. So you have to take your hydrant I don't know stand or appliance from your truck, find the hole in the ground, open it. Sometimes it's, you know, rusty, or it's under grass, or whatever. It takes time. That's why we always say that as soon as we arrive on the scene, one team goes inside, the other team prepares water supply.
Speaker 1:You're sure that the truck will last a few minutes and after those few minutes. You want to have something. Exactly, exactly, and the hydrant is connected with the truck. I assume because the truck has the pump.
Speaker 2:Yeah, but the hydrant should have some pressure itself.
Speaker 1:Yeah, but it's not that you can put a hydrant directly to a nozzle and apply.
Speaker 2:Well, you could probably do that. There will be limited. I mean, if you are, let's say, uh, still uh urban area and have a grass fire, yeah, then you can probably find a hydrant and maybe just go if it's like within the reach, but but then yeah, the thing is that you can place your truck anywhere, but you cannot pull out the hydrant from the ground to make it closer to the fire.
Speaker 2:So you have to really be lucky to use this kind of scenario. So we opened the hydrant. Hopefully it works, hopefully there's nothing missing. It used to have aluminum valves, so they were stolen by the gentlemen that collect Collectors, collectors that sell them later. Now they are plastic, so there's less problem. Hopefully it was dehydrated, dewatered if it was used before winter. So nothing froze, nothing exploded underground and it's still operational. Actually, we as firefighters very often go to our protected area and simply check the hydrants If they're working and we have frequent updates about them Not in an action, but just outside of action.
Speaker 2:Yeah, just between them, and sometimes it's done by the firefighters from the fire station, but sometimes it's done by the prevention, by the prevention, but probably less and less. They have more and more work in buildings, in auditing buildings and making sure everything's okay.
Speaker 1:Yeah, and so you described the exterior perimeter hydrants. How about the interior of the buildings?
Speaker 2:So why I said about the water cannot be squeezed and cannot be stretched? Because there's some pressure in the hydrant network and if you take water from a hydrant by one outlet, one hydrant from the hydrant network then obviously the pressure will drop. If you want to have more water you can take another hydrant and another, but at some point you'll have not enough pressure, so that will turn into less flow rate yeah in. In certain circumstances it's all hydraulics. I won't go into it, but there there's a limit yeah, there used to be.
Speaker 2:there used to be, uh, less effectiveness, incorporating with the hydrant network management. Now it's a way better situation. I've been a deputy fire chief responsible for operational activity of the headquarters in Nijica and I was able to have frequent meetings with these guys and whenever we wanted to have pressure boosted by them, we just said that, boost the pressure, and so on. Sometimes they would tell you back in the days we cannot do this because somebody's toilet will shoot out Stuff, like that happened before the renovation of these networks.
Speaker 1:I mean we've seen in those wild and urban interface fires when large area. Wildfires approach the cities, how hydrogen networks can get overwhelmed, because I mean you design this network to secure you for a fire of a single building maybe two three buildings.
Speaker 1:But if there's a hundred buildings burning at the same time in the neighborhood and you want to get the water from all ends of the network, you eventually cap out the ability of that network to provide pressure. So I think many of us have seen recollections of firefighting in some of those wild and urban interface fires where you basically run out of the water and it's not that there was insufficient water, it's just that the flow rates at every single outlet of that system were compromised because too many outlets were open at the same time. I'm luring you into the building because the question is why do you even bother us engineers with designing an internal hydrogen network inside the building? How much that internal uh network of of water pipes really changes the battlefield? Yeah, for you, perhaps I you know what. I'll ask you a different question to start with. Yeah, how much does the 52 water hose stretched fully full of water wave like? What is the, the mass of that hose?
Speaker 2:because the water in it weighs 42 kilograms and itself weighs another two or three.
Speaker 1:So 45 ish per 25 meters per 20 meter, so you have like 200 meter line. You have? Yeah, you have like 200 times for 45 kilos.
Speaker 2:It's half a ton.
Speaker 1:Half a ton.
Speaker 2:Good luck pulling that behind you and moving with that, but you already also have 500 liters water in it from your pump, so that's a quarter of your water that you brought on wheels just to fill in the water.
Speaker 1:And now you can start extinguishing. But this 500 went to and this is the, the 52 which I. I've attended the brilliant polish main school fire service, the fire academy today. So you understand, that's your end hose. You should go with 75s yeah, from the truck.
Speaker 2:so that's how much like six, eight hundred eighty eighty eight think 88 kilos per section.
Speaker 1:Yeah, that's why you need water points inside the building.
Speaker 2:Yeah, that's one thing. And also, look, I mean there's a variety of systems. There's dry and wet pipes. Even dry pipes are useful, provided that they are maintained. The biggest problem is always that you always that somebody will throw trash inside. Can you define the?
Speaker 1:difference between dry and wet pipe, outside of the fact that one is dry and the other is wet.
Speaker 2:Well, there's already water in those wet ones, and sometimes this water comes from an internal water source with pumps.
Speaker 1:So at the end of the outlet you open it, there's already water in it like a tap in the kitchen.
Speaker 2:And you just take whatever hydrant is there. So basically you don't have to bring any of your equipment. You just enter and, from a certain point, take it and use it.
Speaker 1:And the dry system. Do you have to fill it with water on both ends, or it's just yeah?
Speaker 2:yeah, it's like you don't have to do your stretch inside the building. You just put water to the inlet by the entrance or whatever point normally by the main entrance and you push water inside and then by fixed pipes it arrives at a certain floor and then you open it and just continue from there. But you basically you conserve time and you conserve your energy because you don't have to carry so much equipment.
Speaker 1:So it's like pre-stretch hose in your building.
Speaker 2:Yeah, yeah, exactly that Okay. Exactly that.
Speaker 1:And the biggest challenge with them is maintenance. Yeah, yeah.
Speaker 2:We would like to think they work, but many, many cases they don't work. They're like couplings missing or valves missing. So you want to have water on the third floor but it's already leaking on the second floor. Somebody put trash candy paper inside. It's stuffing your nozzle, or somebody put trash candy paper. Inside it's stuffing your nozzle.
Speaker 1:Normally we should use a smooth board then, because it can shoot out any garbage that it takes into the nozzle, and so on, Of course, like if it's a wet pipe and there's a hole in it, you'll know. Another question is what kind of flows and pressures are present in those hydrogen networks inside the buildings?
Speaker 2:Oh, really, here I don't have a very good orientation, but from what I remember, those inside hydrants we don't speak about standpipes, but inside hydrants they should have, I think two bar pressure. They should have. I think two bar pressure. They are tested for two bar pressure and probably a liter or a liter and a half per second.
Speaker 1:Okay, and how?
Speaker 2:about space, then it's for the incipient stage. So that should be more than enough If there's somebody that will actually take the hose and extinguish it. It's like you take this.
Speaker 1:It's like you have eight garden hoses for a bonfire you just you can do whatever you want with this comparison, which which translates into 30 showers overkill yeah basically, or 100 buckets, yeah, and buckets, 100 buckets, I love it and how many of those you would need, or how often would you like them to be in the building to make sense, like every third floor, every floor, every 50 meters, every half a kilometer? I don't know.
Speaker 2:Well, these are governed by prevention laws, the fight prevention and I'm not really well versed on these. I haven't been engaged in this, I was an operational firefighter, but from what I know well, basically we have to differentiate. These are for the public, to have an immediate action. Well then they can be used by a firefighter. If a firefighter knows there's a hydrant inside and the commander assesses okay, there's a good chance you can access this point and use the hydrant. So maybe you go now while we prepare backup, while these guys are stretching and preparing, another attack team is entering. You may go and try to see. It's a different story with uh, with uh standpipes, because standpipes you don't count on what's there, but standpipes, if they have a, be there wet. If they're wet, then then your pump can be used from the building. Then you have to have some operational knowledge. It's not like you go and there you know nothing. You should be there before the fire. You know.
Speaker 1:Can you please explain the difference between the hydrant and standpipe? It may be ridiculous for you, but for engineers it's not.
Speaker 2:Well, I would rather expect that it's for firefighters because, maybe it's not so obvious, so I'm hoping I'm not making a fool out of myself and the whole world is listening.
Speaker 1:The whole world is your time, simon. Tell me what is the finest stand.
Speaker 2:Well, a standpipe for me. In my understanding, a standpipe is a system of pipes fixed to a building that serves the purpose of extinguishing a fire by firefighters.
Speaker 1:So it's not that the public can access it. You have to have the special hose you have to have a special key to it special key to it.
Speaker 2:Yeah, I mean I have no idea how it works in different countries. I mean there could I I envisage the possibility that it's used by the general public, you know. But I would imagine that the capacity, extinguishing capacities of these are comparable to firefighting extinguishing capacities. Therefore, it may be too much for a regular person who's not ready, let's say, to have a nozzle that gives six bar of pressure and with the resulting reaction force.
Speaker 2:You know Newton's law action and reaction firefighter knows he should be he or she. They should be down on their knees. You know maneuvering their hips, you know kind of a sexy dance, rock and roll, but not to get knocked over by the opening of the nozzle.
Speaker 1:I think a lot of people are very, very surprised the first time they feel the force of a full firefighter's equipment Like it's way more than eight garden hoses.
Speaker 2:Yeah, it's definitely way more.
Speaker 1:Yeah, and the hydrons would be something accessible to public and sometimes they would also have like a hose on them, a hose with some sort of device at the end, nozzle at the end.
Speaker 2:It's either like a flat lay, that is, a hose that does not have a reinforcement inside, so it's flat. So you have to stretch it, then go to the valve, open it. It will fill with water. Therefore it will grow and from flat it will have a cylindrical shape and then water starts going. Normally the nozzle should be closed. Yep, but there's also stiff what we call stiff hoses. That is like a is like in a hose reel. It has already a cylindrical shape. This one can be wet inside the other one. For them to be stored, they should be dry. The wet one will be able to give less water.
Speaker 1:So presence of those standpipe systems that are meant for firefighters simply allow you to skip those sections of early operations and then, eventually, if that's not sufficient, you will add more and more and more to them.
Speaker 2:Yeah, correct a hydrant placed in a specific location that was assessed. It's a good place to put a hydrant, because maybe this entrance to a storage place or something In the same manner let's say, an outlet from a standpipe is in a vestibule that leads to a corridor. Yeah, so it's still a safe place, maybe separated by fire separation so that you can approach as close to the fire as possible and then start your firefighting from there.
Speaker 1:I think a lot of. Actually, this part I think a lot of fire engineers would be familiar with, because I'm not sure about all the places in the world, but we are doomed about calculating the range of the hose and does it reach the most remote part of your building? Because the law requires you to place them in such locations that you can reach them. So we're drawing those hose lines in our AutoCAD drawings you know the plans of the building to make sure that it's reachable. We're narrowing on time, but I really wanted to ask you some questions about your feelings and feel free to say whatever you like. You're retired, so they cannot fire you anymore.
Speaker 1:Your feelings about. Look, I'm a fire engineer, I want to do good job. There are some law requirements. They can tell me I need a hydrant every this and this meters. It shall provide one liter per second water. You know, there's a clause in my law. I can just take it and I'm done. But what if I want to do a good job? What if I really want to try and make a difference in my engineering? First, is this water supply a place where I can make a difference, Like by designing it better? Can I help you in any capacity? Or it's meaningless and I should find some other things to do?
Speaker 2:Well, I'm not sure if I'm the proper person to judge somebody's work. There's been so much knowledge and experience put into writing fire codes that, well, as long as the fire codes, then well, as long as the what I have a saying that, as long as the conversation continues between the operational firefighters and the prevention officers or fire engineers, we're on the, we're on the safe side, because the environment will be constantly changing. Yeah, but really I mean, our biggest challenges and concerns are outside of the scope of the work of fire engineers Vandalism, you know like somebody will just mischievously break something or steal a.
Speaker 1:Capsules or whatever.
Speaker 2:Yeah, whatever is necessary to operate it, you know, without loss of time and so on. So sometimes we keep in the back of our heads that we would like to be able to use the hydrant, but just for any case, because our lives are on sake, we will still refer to the traditional way of firefighting.
Speaker 1:And, in places, more of those hydrants, those tentpipes, to improve your chances. What would that change? That would probably change the amount of time you need to get water at the location where you want it, Because it's not that I can increase the outflow because of the pressure considerations that you've already mentioned. Right? So it's all about saving time in the end.
Speaker 2:Well, for me, yes, it is. But for me, as I said, you know, I have a philosophy. I mentioned it partially in the beginning and I will, let's say, say the full phrase Nobody builds anything with certainty it will catch fire. But firefighters know that whatever was built by human beings will sooner or later catch fire and we will intervene. Sooner or later catch fire and we will intervene. So in a way, you know, we have very little allies in the world of firefighting, because we are always the guinea pigs.
Speaker 2:You know, when shit hits the fan I'm not sure if I can say this Then we are the ones to intervene and it rarely causes anything to improve, other than when there's tragic loss of life, avoidable loss of life. So if we could really convince everybody that please be sure this will catch fire and then make sure that by saving the investors money, you are putting firefighters in danger because you can fulfill some requirements, but you can also build a better system that will protect the building better, you know, because then you know, I see there's many factors in play. There's insurance money, there's, you know, cost of running the building and so on and so on.
Speaker 1:I think it also the role of those systems also would depend on the scale of the building really. So if it's like two-story tall residential building that you can access from any external location you want, probably it's less of a trouble. But if you you have a 200 meter tall skyscraper, the reality of you having any any chance to to fight fire at the 50th floor is, yeah, it's really zero. So, first of all, the building shall defend itself, I guess.
Speaker 2:So sprinklers and stuff and have any chance to fight fire at the 50th floor is really zero.
Speaker 1:So first of all, the building shall defend itself I guess sprinklers and stuff and have wet standpipes and have good pumps, because in that case reliability of that water supply is really everything, because there is virtually zero chance that you can bring your own water up there right.
Speaker 2:Yes, it's very problematic.
Speaker 1:I mean you have to combat gravity and in this case the engineer has some sort of tools like pump systems, additional water supplies also those water tanks and for external firefighting, in terms of we've already mentioned wildfires and those areas and those fires which would have extreme large areas, not necessarily, you know, 50 megawatts in a 50 square meter of an apartment, but let's say 50 megawatts spread across a half a kilometer of a fire line. How different is water logistics in that case, and is there anything engineers can do to support that kind of operations?
Speaker 2:You mean like wildland? Yeah.
Speaker 1:Wildland or just large fires. When the wildland fires reach the neighborhoods, I mean we're lucky in Poland we didn't have those yet in that scale.
Speaker 2:Yeah.
Speaker 1:But yeah.
Speaker 2:I mean then the problem is that we have to choose between the amount of water and the weight of the hose, because in these fires you really have to make your steps. You know like you make your steps every day 9,000, 10,000, there you just go back and forth. So then you take a lighter hose or you take some water on your back. It's very straining and fatiguing, but what comes into play are airdrops, you know, like from bambi buckets, from helicopters or from planes. You know there's there's a variety of ways. I mean in in the united states and probably also in different countries where the there's a variety of ways. I mean in the United States and probably also in different countries where there's a huge problem with low-idle and fires.
Speaker 2:They also upright some dry chemicals. You know they just try to come up with different ideas. Just one correction. I just quickly checked these one liter per second are correct, but for internal hydrants and for external would be like 10 times that. So 10 liters per second, yeah, but for internal hydrants and for external would be like, uh, 10 times that.
Speaker 1:So 10 liters per second.
Speaker 2:Yeah, yeah, okay.
Speaker 1:Good, good, good. Uh, I remember quite clearly when there was a fire of the Notre Dame cathedral and president Trump tweeted like send the air tankers to take it down. So he was probably he was probably the pioneer of compartment fire tactics with air tankers.
Speaker 2:Look, surrounded by water, yeah, the Notre Dame. But the problem is that this water can just make the whole building collapse. You know that's not good for architectural monuments, historical buildings.
Speaker 1:Okay, shimon, thank you very much for for giving a water one-on-one to fire safety engineers. I always say that there are rules to be followed and you obviously show a huge respect to those rules, uh, and people who are writing them, and I also think it's a great achievement that we have codes and standards and and some ways to to really, you know, standardize the way how we apply stuff, but there's also huge benefits of people understanding what's the purpose of them doing so. You know you can apply those liters per second on your drawings in AutoCAD for your entire life, but not know how much a hose weighs. And I think having conversations like this, which bring this craft of firefighting closer to the fire engineering audience who are designing those systems for you, I think there's a huge benefit for that and I'm sure everyone who listens to to this episode enjoyed that and learned something new I definitely did so.
Speaker 1:So thanks, uh, once again for for joining me in this in the podcast well, thanks for having me.
Speaker 2:It's, I don't know, the third or fourth time, so I'm really honored and the message to everybody look, it's summer and since we're talking about water, don't forget to hydrate yourself okay, yeah, keep hydrated, okay, shimon.
Speaker 1:Thank you so much, and see you around see you and that's it.
Speaker 1:Thank you for listening. How much water do we need to find fires and how do we get that in the location where fire is? That were the main questions I had to Shimon, and I think he answered them both fully to my satisfaction. It was a pleasure to discuss Water 101 with Shimon. I hope you've learned something new.
Speaker 1:I hope that fire engineers, who never had a chance to view these elements of fire safety design through the eyes of firefighters, had a chance to view these elements of fire safety design through the eyes of firefighters, had a chance to actually think about those matters differently than they did before. In the end, what supply system is something we design precisely for firefighting, precisely for firefighters? We really need to make sure that these systems work in such a way that they benefit from them in the maximum way. So no space for wishful thinking, no space for us doing the design in a void. We need to talk to firefighters, and that's what happened in this podcast episode. Uh, shimon, thank you once again for appearing in the fire science show. You are a brilliant connection between the world of fire safety engineering and firefighting and I am so grateful that you allow me to tap into this connection and and join our beautiful groups together, and I think only good stuff can happen from more discussions and more podcast episodes like this one.
Speaker 1:I'll be wrapping up quickly. I'm on vacations. I try to stay hydrated, as Shimon asked, so I hope you're having a good time in your summertime. I hope you are resting a little bit with your families and if, in that time, you feel like learning some more fire science, there will be another episode next Wednesday waiting here for you. Thank you very much for being here with me. Cheers, bye.