193 - Fire Fundamentals pt. 15 - Extinguishing systems with Bogdan Racięga

Welcome to another Fire Fundamentals. This time the episode is focused on various extinguishing technologies. Invited guest - Bogdan Racięga, Director at Baltic Fire Laboratory and expert in fire protection systems breaks down the fundamental differences between suppression and extinction technologies and how they work in real-world applications.

• Clear distinction between suppression systems (control fires while meeting temperature criteria) and extinction systems (must completely extinguish fires)
• Types of fire protection systems including water-based (sprinkler, water mist), foam, aerosol, and gas systems (no fire-balls :))
• Technical parameters affecting performance: K-value, nominal working pressure, RTI, discharge areas
• Areas of application, eg. why water mist systems can often be preferred for high-rise buildings due to smaller piping and reduced weight
• How temperature ratings and RTI affect sprinkler activation timing and performance
• Challenges with concealed sprinklers including maintenance issues and delayed activation
• Testing procedures for water distribution patterns and certification processes
• Differences between high-pressure and low-pressure systems in various applications
• nuances related to the role of an accredited laboratory (ISO 17025) and a certification body (ISO 17065)

Thank you to the SFPE for recognizing me with the 2025 SFPE Fire Safety Engineering Award! Huge thanks to YOU for being a part of this, and big thanks to the OFR for supporting me over the years.

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

Chapters

• 0:00 Introduction to Suppression vs. Extinction
• 9:41 Defining Suppression and Extinguishing Systems
• 24:37 Types of Fire Protection Systems Explained
• 36:13 Technical Properties of Water-Based Systems
• 51:13 RTI and Activation Mechanics
• 1:05:07 Bucket Tests and Concealed Sprinklers

Transcript

Wojciech Węgrzyński: 0:56

Hello and welcome to the Fire Science Show. Last week we had fire fundamentals and guess what? This week we're talking fire fundamentals once again. Last week we've talked about jet fan systems and ventilation and today I'm venturing in the world as far from that as possible. Well, maybe not that far. Actually, I'm switching the theme from air to water or to other extinguishing agents. From air to water or to other extinguishing agents and in this episode of Fire Science Show we will cover the basics of suppression and extinguishing technologies out there. So we will talk about water-based systems, we'll talk a little bit about other types of extinguishing systems that you can find out there and obviously I'm not an expert. I feel comfortable talking about jet fans, pressurization or any sort of smoke control for you, but I'm definitely not an expert in any suppression or extinguishing applications. I even mix the terms. So I've invited an expert that I know and I respect highly my good colleague, Bogdan Racięga. Bogdan is a director at the Baltic Fire Laboratory, chairman of the scientific council at the International Water Misassociation and a member of numerous NFPA panels, like 750, 502 or 409. And the Baltic Fire Laboratory it's the laboratory in Poland that specializes in testing suppression and extinguishing applications, and I've been there multiple times. I've seen the experiments out there. It's very impressive and definitely, definitely they've gained a huge body of knowledge on how those systems work.

Wojciech Węgrzyński: 2:23

In this podcast episode we will go a little bit deeper into how they work, but really the point is to recap the fundamentals, to test the point of fire fundamentals. Let's recap the fundamentals and learn the basic differences between the systems. What are the parameters that characterize the systems? How do those parameters turn into actions on buildings? Why would you care about pressure? Why would you care about discharge? How does it change the outcomes on the fire? How do you choose the correct application for the problem at your hand? These are the things that I wanted Bongdan to cover and I think he quite well delivered that. So even if you're an expert in suppression or extinguishing, this episode should have some good nuggets of knowledge even for you. And if you're coming to the world of fire from structural engineering, mechanical engineering, chemical engineering you're not a fire safety engineer but yet you have to work with the fire problem and you have not really been exposed to those extinguishing systems, this is an episode for you that will give you a kickstart into the profession and cover the basics for you, so I'm really proud to introduce you to this episode. I hope you will have a good time listening to it. Let's spin the intro and jump into the episode. Welcome to the fire science. My name is Wojciech Wigrzyński and I will be your host.

Wojciech Węgrzyński: 4:02

This podcast is brought to you in collaboration with Ofar Consultants, a multi-award winning independent consultancy dedicated to addressing fire safety challenges. Established in the UK in 2016 as a startup business of two highly experienced fire engineering consultants, the business has grown phenomenally to eight offices across the country, from Edinburgh to Bath. Colleagues are on a mission to continually explore the challenges that FHIR creates for clients and society, applying the best research experience and diligence for effective, tailored solution. In 2025, there will be new opportunities to work with OFR. Ofr will grow its team once more and is keen to hear from industry professionals who would like to collaborate on fire safety features this year. Get in touch at ofrconsultantscom.

Wojciech Węgrzyński: 4:46

Hello everybody. I am here today with my good friend, bogdan racenga from baltic fire laboratory. Hello, bogdan, good to have you in the podcast again. Hello, boy checking. Thank you for invitation again. Yeah, thanks, man. I so many times in my life when I said I'm having extinction. You've corrected me I'm having suppression, so I thought that perhaps let's clear this once and for all on air. But really there's so many nuances around sprinklers and extinguishing and suppressions that I believe a lot of people will benefit from learning. But let's start with that one like extinction versus suppression. Why the hell are you correcting me all the time, bogdan?

Bogdan Racięga: 5:22

Yeah, exactly, because, especially in our Polish language, there's not exactly a word about the suppression system. The people are saying extinguishing system, extinction system. So in our laboratory, when we are testing this active fire protection system, we have clear differences between the extinguishing system and the separation system. So, in very short words, the extinguishing system is a system which must extinguish the fire in the specific time. If this time is like 15 minutes, 30 minutes, you need to achieve the full extinguishing of the fire which is in the specific place, the most probably in our enclosures. And this is the extinguishing system. And the suppression system has a specific time to achieve specific suppression criteria. This suppression criteria means ceiling temperature and the damage of the object which is in the fire Actually makes sense.

Wojciech Węgrzyński: 6:19

So extinction would be like getting rid of the fire completely, and suppression would be minimizing the outcomes of the fire, correct?

Bogdan Racięga: 6:27

And then you have the specific application. I give you example for that. So the extinguishing system we are using mainly in the machinery space turbine enclosures. So then the system is dealing with the fire itself. You do not counting on any fire brigade or any crew in this factory, on this marine vessel, for example. So the system inside the laboratory is tested in such a way that it's able to kill this fire within 15 minutes. If you are, for example, telling about the IMO 1165 test methods for the total flooding.

Bogdan Racięga: 6:59

Then the suppression system, like we have the systems with the sprinkler and the water mist in the hotels, for example. So this system has some limits on the ceiling in terms of the temperature. We can divide the fire tests to the reference tests with the sprinkler and the water mist. Then the sprinkler system we are running first. This is a test that is making a base for our test criteria for the water mist system and the water mist system in terms of the temperature on the ceiling shall be on the same level or better, and the damages on the object, like the office desk and the sofa, should be in better results. It means the damage with the water mist must be less.

Bogdan Racięga: 7:39

Like the sprinkler. There are as well some test protocols that you mist must be less like the sprinkler. There are as well there's some test protocol that you do not need to run the sprinkler system when you are testing the water mist system. So there, you have clearly defined the temperature on the ceiling that you cannot cross and the damage on the object which is in the fire, and this is suppression. It means after 30 minutes, still you have the fire, but you are going to terminate the test.

Wojciech Węgrzyński: 8:03

I'm going to be called a lobbyist, but I always wondered why sprinkler systems do not require a reference. What are these tests to compare them to? And perhaps that's not good Damage. We'll go back into the systems because that's on the long list of questions they have for you. But you mentioned damage to the items around the sprinklers or whatever device is operating. So what do you actually mean by saying limiting damage? How do you assess the damage? How does it look in the experiment? Yeah, okay.

Bogdan Racięga: 8:32

So let's fix to the object which is in the fire, which is the sofa. Okay, it consists of the two sofas, which is like the eight materats, and we have the sidewall test, for example, where we have the sofa in the fire and after 30 minutes the sofa cannot be burned more than 40% of the total volume. So after the fire tests, we have the special technique as a laboratory to measure this 40%. If we are above, it means failure and if we are below, it means pass.

Wojciech Węgrzyński: 9:04

And I guess every different protocol that you test for would have its own criteria. I remember when I was visiting your laboratory, you were having this vehicle mock-up and you had some wood planks next to the vehicle. Yes, so these were the damage targets for assessments Correct.

Bogdan Racięga: 9:19

So in this test which you've seen, it was IMO 1430 with the passenger vehicle which representing the fire, or the car on the 2.5 meter ceiling, which is quite low, as we discussed, and inside there was the 12 pallets. In this test the damage itself on the pallets is not counted, it's counted the temperature on the ceiling. And then important in this test is if the targets, which was on the left and on the right, the play woods, are ignited or not. And then this information, if the play woods are ignited or not, for the lab is a challenge as well sometimes to found, because the wood, despite is wet by the water, may burn within 400 Celsius even.

Wojciech Węgrzyński: 10:06

I knew it's a good idea to bring you to the podcast, and the stuff that we're discussing right now is so important to engineers to understand what is behind the numbers. Like, people very rarely know what does fire resistance of 30 minutes really mean unless they've seen a fire test in a fire laboratory or have a very specific methodology to assess that this particular device is fit for actually quite a representative scenario of hazard. Do scenarios like that like they really exist for almost any accommodation? Like every time you see a different sprinkler type, it means there's a specific test describing the fire for a specific location and it has to go to protocol, or it's like I don't know. Uh, they use tests for car parks as I say, okay, this is gonna be fit for, I don't know, changing rooms and and bicycle storage and and metro stations. How does it work?

Bogdan Racięga: 11:12

okay, so I I will go in such way with the sprinklers. You are mainly have this value of the millimeters of the water in the square meter which you have, the value for the specific hazard and you can follow with this value, okay, okay. Okay, I explain this the best, I think, with reference to the performance-based system. It means the water mists. Why it will be better?

Bogdan Racięga: 11:38

Because when you have the fire in the office and the fire in the car park, those are the two different fires and, of course, the car park is the most challenging one comparing to the office, because of the quantity of the fuel load which you have in the office or in the hotel, for example, nozzle or sprinkler head which is dedicated for the car park or dedicated for the office.

Bogdan Racięga: 12:04

The quantity of the water for the car park is much higher because it's related to the density, yeah, so oh2, like for the sprinklers, 80 millimeters per square meter in the europe which is quite common. It's a kind of value for the water-based system. Sprinkler with the water mist is different because, again, you have the reference tests with the sprinkler system and after you are creating your pass-fail criteria based on the sprinkler test. So where the water mist system if it's high pressure or if it's low pressure. In the car parks the density comparing to the OH1 commodity, like in the office, is much, much higher. And it's important as well in those tests that in the car parks, for example, the area of the operation, call it the most demanding area, it's 144 square meters.

Bogdan Racięga: 12:52

And in the OH1 spaces it's like 72 square meters. It means in our tests we are testing the system and there are specific heads sprinkler heads or water mist heads which can operate during the test and if some of the heads will operate outside of the specific ring, the test is failed.

Wojciech Węgrzyński: 13:15

It means this justifies you that the system was able to stop the fire spread and the temperature are maintaining very well on the ceiling so you have also like reference things, like the areas like the flow rates, uh discharge values that allow you to generalize some, some concept, and still, I would assume, those uh correlation that you need. This particular oh2 setting for carport comes from experience and testing. Yes, um, we brought up many names for those different systems, so perhaps let's clean this up a little bit. I don't think I've had such discussion in Fire Science Show yet. So we were talking about Sprint, we were talking about Watermist. Let's clean it up. What types of systems extinction or suppression systems, what kind of systems are there on the market that that the fire engineers could meet in their jobs?

Bogdan Racięga: 14:04

okay, so generic, about the system which you can find everywhere. Of course. We have the water-based system. It means the sprinkler, the water mist. Then we have the foam system, which are helping us to fight with the pool fires, mainly areosol system, the system which are testing a lot now because of some changes on the market, gas system, like the clean agent inert guard system. So those are mainly those which I mentioned here, and each of them has a specific purpose and application as well. You cannot use each of the system to all the application, so the key point is to understand which system shall be addressed to your application. This is the most critical to understand and know the strong sides and the weak sides as well of those extinguishing or the suppression systems.

Wojciech Węgrzyński: 14:58

You have not mentioned extinguishing balls.

Bogdan Racięga: 15:00

No, no, this is something that I'm struggling a lot because, from last to most, these extinguishing balls are called aerosol generators, because the aerosols are quite successful on the market and there could be serious competitions for the protection of some applications. So those guys are starting to tell that this is aerosol generator. It's completely not. Maybe it's bomb, but it's not the generator of aerosol definitely.

Wojciech Węgrzyński: 15:32

No, definitely. Okay, good, so we would have water-based systems and we would have gas-based systems. We would have aerosol-based systems, A lot of stuff to choose and the basic differences between, let's say, the gas-based systems. We would have aerosol-based systems, a lot of stuff to choose and the basic differences between, let's say, the water-based systems. So I mean, it's obvious that water mist gives you mist or fog. The sprinklers give you this nice big spray of water. I think the fire engineers would intuitively understand that very well. And from a technical perspective, like on the technical properties when you design those systems, yes, what are the major differences?

Bogdan Racięga: 16:06

okay. So each sprinkler the water means we must divide to the open nozzles or bulb nozzles, correct automatic sprinkler. So this open nozzles, called the dilution theler world, are the systems which are connected with the dry pipe system. It means you have the electronic valve which is triggered by the fire detection system and then you are releasing the water for the specific protection those systems are common in protection of some industry parts like the conveyors, tunnels, tank protection by the cooling as a deluge system.

Wojciech Węgrzyński: 16:43

So you have like 20 sprinklers on a pipe and they all go off together when the fire alarm tells them to do so. Exactly, I think that's what we do in tunnels, right.

Bogdan Racięga: 16:52

Yes, exactly, and you have the specific area and the quantity of these heads, because this is again connected with the area of the operation and the sizing of the pump. So you cannot run more than calculated sprinklers in specific zones because then you do not reach the pressure which is the nominal working pressure on the head. So when in the laboratory you have the nozzle on the sprinkler tested with the two bars, you must deliver the two bars during the fire, in the tunnel, for example. This is the critical value that the flow rate, together with the pressure and the curve value of the nozzle must be respected in case of the fire. That's why there are some safety factors on the design side added, despite the tests done in the laboratory and after the open nozzles. Of course we have the bulk system, very complex sprinklers with the bulbs inside glass bulb Depends on the sensitivity. You have this RTA number which is defining how fast are those bulbs. This can be the standard fast response or even super response for some very specific applications. And those sprinklers you can find in the hotels. There is digital buildings, storage areas, garages, commercial buildings, everywhere. Almost those are the most fun with sprinkler system. Come on. So this was about the sprinkler.

Bogdan Racięga: 18:13

Now the area where is the most challenging for me and interesting as well, because we are running 65% of the old tests with the Waterme system. So again the open nozzles. It means triggered by the fire detection system and they're connected with the dry pipe. All section is going in the same time and the quantity of the nozzles multiply by the flow rate, giving you this information what the pump's size should be. Typical application machinery space generators, tunnels, aircraft, hangars, turbine enclosures, specific hazards, like the other machinery spaces. So those are the open nozzles. Then the bulk nozzles, the water miss nozzles has mostly faster RTI because the nozzles are quite smaller. You have the low pressure system, you have the high pressure systems.

Bogdan Racięga: 19:10

So we've seen those water miss systems, especially on the marine from the 30 years because it was there. Now in the land are widely used because in the European 4972 just entered, like five years ago. So now the engineer is able to put in the technical building specification the standard. Previously it was challenging because there was no standard. So we've seen those systems in the hotels, residential buildings Again about the marine in all these public spaces, restaurants, cabins. So very similar application to the sprinkler. But there are some areas where the sprinkler are better and where the water miss are better. Example Warsaw is a great example because it's buildings have a high-pressure water system because of the hate to reach to the last floor and the water head automatically as well.

Bogdan Racięga: 20:10

Why would that be Okay? Because with the sprinkler system when you're protecting the high-size buildings you must be challenging this water head. It means your pump must deliver to the dry riser the most probably or there are the wet risers as well the specific pressure For the certifigular pumps for the certain value. It's impossible to reach more. Then you need to build inside of your floors the water tanks for the sprinkler system. With the water system you have one tank in the basement and one pump unit in the basement and you can protect all the building. And I know in the Warsaw the building which is the highest rise, which has 22,000 nozzles of the water nests, which is quite massive, and those are the two pump units in the basement and this is quite a nice project. This is a few in Warsaw quite prestigious projects and luckily in Warsaw is the highest building in the European Union as well.

Wojciech Węgrzyński: 21:13

Half a meter taller than short. Yes, to your face, our British colleagues, we have a half a meter taller building, apparently not by accident Because of the antenna, because of the antenna only. No, no, it's a structural part of the building. It's important. Okay, let's not go there. And also, for me, a difference that was obvious when I was talking with people like the difference between Splinkus and Watermist, for example, was with the piping. So, so every time it was brought up on the project, people oh, I would prefer, you know, a water mist because it has this, those nice little pipes and and not, uh, big pipes like, like sprinkles have. So perhaps let's talk, let's talk about that exactly. So it's those differences.

Bogdan Racięga: 21:55

Yeah, it's very good point for attack and, of course, with the water miss system, especially with the high pressure, you are able to drop the size of the pipes which delivering the water to the 38, 42 millimeters, maybe 60 millimeters as a main pipe which is just going from the basement to the 52 floor, but with the sprinkler system we are talking about 150 to 100 millimeters. And then we are going to the weight of all this system, which is a crazy with the sprinkler. So, as I told, the sprinkler is good for some application and the water mist is perfect for some and for the high-rise buildings the water is really perfect because we are saving a lot of material. Then, with the materials, you have the penetration between the bulkhead, between the walls, between the floors. So all these penetrations are extremely expensive as well and these penetration sizes are as well higher in terms of the price if you have the bigger penetration as well. So this is something that is really good.

Bogdan Racięga: 22:58

Okay, we will get argument, but the water mist system has the stainless steel pipes, which is expensive Anyhow. If you're comparing the weight of the system and the price of the stainless steel, comparing to the weight of the standard seal for the sprinkler installation. The water mist win anyhow with the price Because if we are talking about the 22,000 of the high-pressure water mist nozzles, it's a huge weight of the system. So anyhow, there will be a beneficial for the water mist systems.

Wojciech Węgrzyński: 23:31

I know there's like this market battle between the water mist industry and the sprinkler industry. You see it every day on on real world projects, where people try to replace one solution with another, both. But I like that. There are technical merits at which you can discuss and technical merits at which you want. That is a challenging world, but I like that. There are, you know, technical properties of the systems that you are able to to compare the solutions and actually find one that fits best for your needs. Right? I was noting down, you know, when you were dropping, a technical term we have not explained yet and I have quite a list right now. There's nominal working pressures, k-values, rti, discharge areas, the most challenging location, and so on. So perhaps let's try and cover those. It's supposed to be an introductory episode, so let's try to go through the basics. So first let's talk about the nominal working pressures. You said that you would design for a nominal working pressure, but what does it mean and how much you can debate from that?

Bogdan Racięga: 24:34

Okay. So when we are testing those systems in the laboratory, there is the specific test for the sprinkler or the water mist where we have to maintain the nominal working pressure in the test, which is the minimum nominal working pressure that the nozzle in real life, in the real installation, must achieve. The most probably depends on the calculation. This nozzle is the most furthest nozzle in the section hydraulic section and some of the nozzles which are closer to the pump has higher pressure automatically. And about the deviation for the example, for the low pressure mists we have the 5% deviation. So during the test where we have the 5 bar or the 8 bar for the low pressure mist system, we cannot cross below minus 5% and the plus 5% during the entire test.

Bogdan Racięga: 25:26

The same high pressure systems what we've seen in our laboratory conditions. Sometimes it's better to maintain the pressure in the high pressure system because the high pressure system has piston pumps. It means the characteristics of these pumps are very linear. So you are able, depending on the RPMs on your pump, to set precisely the pressure. With the low pressure system and with the sprinkler system you have the certificular pumps which have the specific curve and characteristics of the pump. So we need to deal a little with this characteristic and some unload valve, pressure reduction valve, just to set correctly the pressure. So those are the main system and the nominal working pressure always must be the nominal pressure in the installation and during the commissioning of the system, when the system is to the authority, this must be checked on this most remote nozzle in the hydraulic section.

Wojciech Węgrzyński: 26:20

if you achieve those, I assume that you cannot have it lower, but what happens if it's higher? Because if you're closer to the pump it must be higher.

Bogdan Racięga: 26:27

Okay. So if you are higher with the sprinkler system, you are delivering much more water. But the sprinkler system of course does not cross like the 10 bar or the 16 or the 20 bar, so we can assume that it's better because you have more water. Okay, in the low pressure system you have this specific five percent because the nozzle of the low pressure mist system are designed in such way, very precise way, that the spray pattern above some limits may change, which affect the test criteria. If you are above, okay, you are delivering as well much more water. It means for the test criteria can be better with the high pressure systems.

Bogdan Racięga: 27:13

We found a funny discovery in the laboratory because all was thinking that sometimes 100 bar is better for the machinery, space and closure. And now, luckily, we get a very big project which we will do in the may, in and in the june and we test again. But two years ago we found that some of the tests you are not able to pass with the 100 bar, but you are able to pass with the 100 bar, but you are able to pass with the 60 bar. Okay. So we are arriving to such a level that the droplets are too small and evaporation is too high because you cannot cool enough the object in the fire. So sometimes the bigger droplets helps better. That's why we seen in the reality this in our laboratory.

Wojciech Węgrzyński: 28:03

And now let's go to K-value, because you wrote K-value again and I know it's interconnected with pressure. So what's K-value and how you described?

Bogdan Racięga: 28:11

it. So K-value is a specific value to the sprinkler head water mist nozzles which define the quantity of the water which can flow via specific sprinkler water. Mist nozzles which define you the quantity of the water which can flow via specific sprinkler head with the specific pressure. So where you have the K value and where you have the pressure, you can calculate automatically the flow rate. And with all these three values you can find the K value, like in the laboratory, some of the manufacturers arriving to the laboratory to check if the K value has this specific value, because we have quite precise flow matters. So we can check this based on the flow rate and based on the pressure. So it's a pure mathematic that you can just calculate based on two of those values, the value number three, but there's also this, I believe, relationship between the pressure and the flow.

Wojciech Węgrzyński: 29:04

The more sprinklers you open, or the more nozzles you open, the less pressure you'll have in your system. So that's why you cannot have too many open, right. If you open too many, you lose too much water and you start delivering not enough to every single nozzle operating. Am I correct correctly?

Bogdan Racięga: 29:22

correct. So there are some standards, that's defining you how much a sprinkler has or water miss nozzle can be operated during the fire tests, and if you cross this quantity the test is failure. So then you have some factors in the test which you can change, which is that ceiling height, which is the bulb temperature, which is the RTI as well, always to arrive to the situation that the system is able again to maintain this fire to such way that stop in the specific area the fire and not more sprinkler heads or the water mist nozzle are operated from the ignition of the fire. So then in the reality, like for the car parks, you have the, like the nine nozzles approximately.

Bogdan Racięga: 30:11

Design of course depends of the spacing of the nozzle and the spacing of the nozzle. This is the value that we need to discuss as well, because the spacing is really critical value and especially for the water mist system, you cannot cross the spacing above this value which was tested in the laboratory, because you are in the really gray area, the same with the sprinklers that you cannot go above the specific spacing because you are going down with the density of the water immediately. So the spacing is a critical value and, as I mentioned nine nozzles for the car park approximately. Then for the water mist, we are testing the data center application with the water mist. Six nozzles for the area design, then some local application system for the four nozzle design. So depends how many nozzles you are able to open in the test. This is the definition for your most demanding area, or call it area of the operation in your specific sprinkler or the water mist system.

Wojciech Węgrzyński: 31:15

And in those spacings, how do you find it? By distance between the nozzles, by area of operation? I don't know a radius around the nozzle.

Bogdan Racięga: 31:24

Okay, so with the sprinkler and the water mists you have just the distance between the nozzles, between the axis of the nozzles. Is it like a maximum minimum? It's a maximum, it's a maximum that you cannot cross because then you are above of the tested heat area. And example when you have the spacing 3.5, 3.5, typical for the OH1 sprinklers, you have like the 12.25 square meter area of the operation for this sprinkler head. Then when you have the water mist, five multiply five you have 25 meters area of the operation. So this is a kind of value that you can easily calculate in a specific room how much nozzles you need to just design that fantastic.

Wojciech Węgrzyński: 32:13

Okay, let's go to rti index. You've mentioned rti index. What does that characterize?

Bogdan Racięga: 32:19

okay. So this is the index which characterizes how fast the bulb is able to broke and activate the sprinkler head or the water miss head. So we have, especially in the old sprinkler installations, call it standard activation, which is rti above 100, that there is the fast response between 50 and 80 rti, if I could remember, and there is the rti which are fast or even super fast, especially in the water mist system. The rti are much smaller, like the fast or super fast is used, so those system, the sprinkler can just start earlier. It's important because this water misnos are using much less water. That's why they need to detect the quite quite fast as well the fire but.

Wojciech Węgrzyński: 33:11

But the rta is not the only thing that defines how quickly it will operate, because you also have the, the temperature rating on the bulb right.

Bogdan Racięga: 33:18

Correct and we are starting from the 57 Celsius. Then we have 68, 73. So this is again connected with the application In the office spaces. You can have the 57 Celsius and normally ambient temperature of this space, like where we are sitting in this office, is 20, 25 Celsius. Your minimum value on the bulb should be approximately 30 Celsius more, so then you are arriving to this 57. To avoid the false alarm and the incidental flooding of your office during the summer and the solar effect, for example, and the bulbs are also color-coded for use.

Wojciech Węgrzyński: 34:01

That's why you would see sprinkles of different colors in different locations. But is it possible that you have, for example, an ultra-fast or very fast sprinkler with activation temperature of, let's say, 71 and a slow sprinkler with 68? Yes, exactly.

Bogdan Racięga: 34:20

So theti? It's connected with the temperature. It means with each temperature you can have a different rti as well. Yeah, so this is important. How big is this bulb? How much this special liquid is inside to expand and broke the bulb?

Bogdan Racięga: 34:38

And I can give you a thing which on the market is wrongly interpreted when you have the lower temperature of the bulb the system is better. It's not exactly like that, because sometimes if you activate the system during the fire test too fast in the beginning, you have a few nozzles, not like one nozzle operated and not four nozzles around, and then this one nozzle is not able to suppress enough the fire. The fire is growing and it's too late when the next nozzle will operate and the test is a failure. That's why sometimes in the tests, the customers here starting from the the 57 bulbs, then they have the failure. They are changing to the 68 or 79 even, which is, for example, specific to the car park in fire tests, where you cannot have so low temperature because you have the gases in the car parks from the various things and you cannot activate the system, incidentally as well where you have no fire so it have the higher temperature on activation on the bulb, it's quite beneficial as well.

Bogdan Racięga: 35:45

But you cannot cross too much because there are the famous 141 bulbs which activation delay is really really high. And I can tell you the our discovery in laboratory, one of the tests where we were testing the data center with the one meter per second simulation of the wind, the data center which is coming from the cooling of the servers yes, 68 Celsius bulb where we had the thermocouple on this bulb activate with the 121 Celsius which was recorded on the thermocouple after two, three seconds. So when you have the cooling of this air, the bulb reacts differently as well because you immediately cooling this bulb itself. So it doesn't matter that the 68 Celsius, it means that you have the temperature around about 68, because it's always higher for the specific time than you have the temperature around about 68, because it's always higher for the specific time. Then you have the activation.

Wojciech Węgrzyński: 36:43

Yeah, I think this world actually of RTI and the activation is very, very interesting and we've done a lot of numerical modeling. That's basically the essence of the issue of Sprinkler and natural ventilation interaction, which definitely will become a podcast episode in the Fire Science Show in the future.

Bogdan Racięga: 37:03

If I can add to this simulation and the RTI, in the simulation you're always assuming that the bulb is fully exposed to the heat which is around it. In reality, different manufacturers have special cages for the bulbs, bulbs which, with these cages, immediately you are influencing this RTI. So this value theoretical one which you are loading to the simulation, sometimes manufactured by the manufacturer, are different. That's why the data from our firefighters show these differences between the theoretical RTI and the real time of the activation. We had discussion, I think, about this in the past, but this is a really, really important finding as well.

Wojciech Węgrzyński: 37:47

If you would like a nuance on this.

Wojciech Węgrzyński: 37:49

I used to be testing the activation temperature for the bulbs for natural ventilators, which are essentially the same bulbs that are used for sprinklers, or natural ventilators, which are essentially the same bulbs that are used for sprinklers, and the procedure tells you to very slowly heat them up to their temperature and 90% of them should operate within a debated temperature, let's say, 3 degrees away of that.

Wojciech Węgrzyński: 38:15

But while we had a bunch of bulbs that were operating within their activation temperature when heated independently, bulbs that were operating within their activation temperature when heated independently, if you put that bulb into a link, into the mechanism that is used, so there's a spring, it's kind of under tension, correct. It took a lot higher energy to operate the bulb. One reason could be the heat losses to the spring mechanism, which was already recognized by Heskestad, the creator of this, and FM Global. So there is a corrected version of RTI model that includes a C1 constant that includes for that. But I believe there was also a mechanical effect of loading the bulb. So if there's some tension on the walls it may take more force to break them like, uh, like a tensile structure of your building. So it's a very interesting mechanism it's really interesting.

Bogdan Racięga: 39:07

I found a few patterns. I can tell you that there is a possibility to increase, uh, the flow of the heat around the bulb, to make a turbulence and speed up the activation as well. So I'm studying this a lot because it's quite interesting to see these developments versus the test results and we found this very interesting. Some of the sprinkler heads, concealed, for example, above the nozzles, has a special holes to increase the heat transfer above the bulb to activate the bulb, above the bulb to activate the bulb.

Bogdan Racięga: 39:42

So, it's a pure engineering. Sprinkler engineering and the water mist guys are doing exactly the same. And just to comment, the bottle between the water mist and the sprinkler I really believe that this is not the way to go, because sprinkler industry currently there are a few companies which add to their portfolio the water mist nozzles as well, because the water mist nozzles start to be really successful. So, when they are making this battle, because there is some association in europe, uh, which is sprinkler, which is the water mist, and this one with the sprinkler is working a lot with the water missile already, so this is going in very good way yeah, okay, uh.

Wojciech Węgrzyński: 40:44

Another one on my list is this church and I would like to ask you about do you even quantify where the water goes from the device when you test it and how uniform that is?

Bogdan Racięga: 40:54

Yeah, okay, so when we have the water misdosen, all the sprinklers installed in the ceiling, we have the installation with the mostly with the Coriolis flow meters and then we have the total flow rate. It depends how many heads are operated. But after the tests, always as our procedure, we are testing these nozzles, which was activated as a single nozzle, only to confirm this K-value. Because as a sample, as an ISO 7025 laboratory, we are just receiving a sample of the nozzles with the specific K value and our responsibility as a laboratory is confirm that the statement of the manufacturer is correct or we need to just change the K value because this K value is completely different, like in the statement for the manufacturer. Maybe in my life I have the two three times. Then K value was not calculated correctly, so, based on the laboratory values, this K-value was updated. But the nozzles which are arriving to our laboratory mainly are prototype nozzles and after it's this process of the implementations to the real product in the life.

Wojciech Węgrzyński: 42:01

And what about the water on the floor? Because you said about what's being released, but I'm asking where it goes. I know the bucket test. I wanted to lead you into the bucket test.

Bogdan Racięga: 42:10

Yeah, okay. So previously we discussed about the performance test. So we don't care about the water which is on the floor, we do not quantify them. We have just the water which is coming to the nozzles, because we have in the data acquisition system the constant information how much water is going.

Bogdan Racięga: 42:27

But if we are going to the component tests to address, for the sprinkler nozzle or the water mist nozzles, what is the spray pattern and how it looks, the distribution of the water around these nozzles, because the people of course have seen the cone and the spray pattern so we have the bucket tests, so the nozzle or the sprinkler head is set on the specific height, as per protocol. Then we have a network of these buckets and we are releasing the nominal working pressure with the water on this head and after a certain time we are measuring if there are any holes in this area, that the water is not discharged enough. So we seen that there's some problem with the deflector, with the spray pattern or with some holes in the nozzles even okay, cool, I I love the bucket test and, uh, you also brought up a concealed sprinklers.

Wojciech Węgrzyński: 43:23

I don't think we've touched that in the episode yet. So what's a concealed?

Bogdan Racięga: 43:27

sprinkler. Okay, so I think it's a sprinkler that when you see in the shopping mall in the episode. Yet so what's a concealed sprinkler? Okay, so, concept thinker, is a sprinkler that when you see in the shopping mall, in the ceiling, you do not see them. Okay, those are invisible almost because it's a special cover which is covering the sprinkler and this cover has a thermal link. It means when you have the fire below this concealed sprinkler, this thermo link must activate and open the sprinkler. So firstly, you have the activation of this cover which is just dropping down, and there inside is a bulb, or there is no bulb, it depends on the design of the sprinkler, or water miss head, which is just pop up from the ceiling, and then you have the nozzles which previously was invisible, the ceiling, and then you have the nozzles which previously was invisible.

Bogdan Racięga: 44:11

I would like to comment one thing only that some of the standardization bodies do do not like those solutions, because I seen many times in the hotels, in the shopping malls, on the ceiling, that the painters which paint the ceilings paint these covers together. So this system is already off. It's shut off because the paint is already on this link and the paint is glued. So if you have the thermo link activated, the cover is not able to be detached and activate the sprinkler. I've seen this many times and this is connected with the problem about the service and the maintenance of the system. So this is the smaller risk, despite. The architects love this solution Because the sprinkler head on pictures.

Bogdan Racięga: 44:54

You know, in the Photoshop the sprinklers are completely removed because they're not nice items. But with the concealed sprinklers this looks very nice, especially for the yacht industry. They really like in the marine the concealed sprinklers. And the water nozzles are concealed as well.

Wojciech Węgrzyński: 45:12

I actually like the look of the sprinklers in the building. I don't find them very ugly. I think it's nice to know that someone has invested in safety.

Bogdan Racięga: 45:22

I like too, and I can tell you that the spacing when we are testing between the concealed sprinklers and the standard sprinklers and the standard sprinkler with the bulb exports are less because of this delay in that.

Wojciech Węgrzyński: 45:36

okay uh, and for the end, when, when you are testing those devices, there are also, like sprinkler or water mist, specific testing systems. So can you tell me about about this world ofUL and other stuff that you have to be certified for to be able to do those tests and the families of protocols that you work with?

Bogdan Racięga: 46:00

Yes, so you use the very dangerous word which is a certification. Okay, so ISO 7025 is a test laboratory. It's not the place for the certified IDs. It's a place where you can test something, which is a process of the certification. I had a small unpleasant discussion about the power of the ISO 7025 because someone is telling that with the ISO 7025, you are able to issue the certificates. You are not allowed to issue the certificates. No, you are able to issue the certificates you are not allowed to issue. No, you have to be notified Exactly, and ISO 17065 is a certification body which is reading your reports from the 17025 and then issue the certificate for the specific test method which was tested in our laboratory and we found the pass or fail criteria for those. So it's not our laboratory. But we've seen a lot of now words with the magic systems that are working so good and are certified by the Terpar body. The ad hoc tests are completely not tests for the certification. So we must be very clear with this.

Wojciech Węgrzyński: 47:15

I'll plug in. I had an episode with Abhishek Chhabra about assurance industry and we've went quite deep into 17025, 17065, and the roles of laboratory and certification bodies. So I would highly recommend not be incorrect as me. Go listen to that episode.

Bogdan Racięga: 47:33

Correct. I spent a very nice discussion with Abishek in Dubai on Intersect this year, so he's a really, really good guy in this area, so definitely I can recommend this episode as well. And about the FMUL. Okay, this year the biggest success which I was working quite hard like the last nine months is to get the UL acceptance and be a partnership laboratory with them for the UL mark certification by the UL, like the UL2167, ul12167a for the water mist system, ul162 for the foam system and UL2775 for the aerosol system.

Bogdan Racięga: 48:21

So imagine that all these protocols from the UL is part of our ISO725 scope of accreditation, is part of our ISO 725 scope of accreditation. It means in front of the PCA Polish Certification of Accreditation we defended that we have the laboratory infrastructure team and the competences to make those tests in the high standard. That's why we were able to be accepted by the UL, but we are not certified by them. We need to really divide this. The same FM Global. We have in our scope of accreditation FM 5560, which is the water mist system, and we are accepted laboratory by the FM to perform some full-scale fire tests which they allow us. So this is the case-by-case project when they are telling you can do this in the DFL and we did with them many, many turbine enclosure tests already and some data centers as well, but we are not certified by them again.

Bogdan Racięga: 49:18

So the certification is in the hand of the certification body. On the marine, it's a cross-society. On the land it's like the FM UL VDS, and so on. Land, it's like the FM UL VDS, and so on. So this certification award is so critical because the people are telling that they have the certified product, but when you start to investigate they have no certified product. They are just using the certification award for their own purpose, which is really not nice, and especially with the car park fires, with the EVs, vojtech you know how many different solutions we have, despite we have the spa standards for the car park. Fire protection with the sprinkler and the water mist and the pure water for the car park is way to go, absolutely.

Wojciech Węgrzyński: 50:05

Bogdan, I think we will stop here. We have definitely not exhausted the list of questions that we had, but this gives us space for a follow-up episode in the nearby future, and I would really love to pick your brain one day as well on the aerosol systems, when you feel comfortable about that, because that's a very intriguing thing for the near future. Intriguing thing for the near future.

Bogdan Racięga: 50:27

Yeah, exactly, and the arousal system are widely used now and after the summer school which we had together with the ITB and the BFL, I got very nice questions from the students from the school. So we are working quite hard just to explain what is the good application for the arousal systems. We are running a lot of foam systems. Especially in this transition of the foam, it's a good topic as well to discuss. So thank you very much. It was again great pleasure to discuss with you and hopefully we will explore more suppressions and the extinguishing system in the future as well together.

Wojciech Węgrzyński: 51:03

The explanation you gave me at the beginning is so easy and intuitive and it makes a lot of sense. It's just you're not really taught that you know in in your fire safety engineer education, which is which is a pity, and that's why, uh, podcast shows like this are necessary for a good continuous education of fire safety engineers like myself yes, and good luck, uh, in zakopane next week for the conferences, for your speech and the kuba's speech.

Bogdan Racięga: 51:29

Fingers crossed. There will be some information about the water system from Poland, but I think I'm not yet ready for the Polish water systems, so we will see how this will work.

Wojciech Węgrzyński: 51:42

We'll update you. Thanks, bogdan. Okay, thank you very much and that's it. Thank you for listening. I hope, even though those were basics of suppression and extingu it. Thank you for listening. I hope, even though those were basics of suppression and extinguishing, you still found some interesting nuggets for yourself. Even if you're 30 years into your career as fire safety engineer, I still hope there was something interesting in the episode for you, and that's that's why I brought bogdan in. He's not an not a salesman for those systems. He is operating a file laboratory that is specifically well-suited to test those systems. He knows their weaknesses, he knows their strengths and he's capable of speaking about those systems from a very unique perspective that not many people in the industry have. Therefore, I found a fire science show a very suiting venue to host a guest like that and give you perspectives just like this. Bogdan is a good friend and we have a good relationship with BFL, so always happy to host a fellow Polish fire safety leader.

Wojciech Węgrzyński: 52:43

In the podcast For me myself, I have cleared out suppression versus extinguishing. Now it's clearly laid in my head when should I call a system in a very specific way, and it actually matters. I've also learned a lot about the differences between the systems and some challenges. The bit about the pumps was very interesting. I didn't know that for water mist, for example, you would use different pumps like piston pumps that would have linear characteristics. Now it feels quite obvious that you do, but it's another interesting bit that you can only learn from fire professionals. I hope this was an interesting episode for you and you would like to have more fire fundamentals coming your way in the Fire Science Show, and I can only promise that we will deliver more. So that would be it for this week's episodes, and I'm looking forward to see you back in the Fire Science Show next week. Thank you.