Dec. 15, 2021

031 - Suppressing tunnel fires with water mist with Johny Jessen

031 - Suppressing tunnel fires with water mist with Johny Jessen

Can water mist be used in tunnels? I wondered that for a long time, and with every tunnel project, many questions around this issue were piling in my head. When dealing with large infrastructure projects you really need to work your way around multiple functional aspects of a system - maintenance, water and power consumption,  drainage capacity, availability of elements and their certification... You would love to focus purely on the fire safety aspect of the issue, but you cannot. Unfortunately, this is often the world of fire engineering. And in this world, we make decisions based on what we know about systems - and when we don't know enough - we test it!

And for the water mist question, I've found the perfect person to give me some answers.  Johny Jessen from VID Fire Kill has visited me in my office and told me about his experience with full-scale fire tests of water mist systems in a tunnel, carried by Efectis. You know he is serious about what he is doing when you learn that the fire source used for this test was approx. 250 MW! This discussion goes deep into the testing and the differences between suppression systems and challenges that modern engineers face in landmark projects.

Johny has asked me to invite you to his LinkedIn profile, where he shares a lot of great resources related to water mist technology - so here you go! And the VID Fire Kill profile.

You may also like to check this whitepaper on the experiments carried in Spain that we discussed in this episode. More materials, including videos of the test, can be found on the project website.

I must also give a shoutout to friends at Efectis who have done some really great job engineering these fire tests! From one fire science enthusiast to another, hats down.



[00:00:00] Wojciech Wegrzynski: Hello and welcome to Fire Science Show session 31 .As usual great to have you here with me. As you may recall some time ago, I visited and very interesting conference on water mist, and I've met quite a lot of interesting people in there and I've been reaching through some of them because they caught my attention.

[00:00:15] Wojciech Wegrzynski: The interesting thing about this water mist, a group of people is that they test everything with huge fires. And as you can imagine, I like large fire experiments. That's what I like most in fire science. And I'm really interested in a group of people who are literally burning down the warehouses to test efficiency of the fixed extinguishing systems? So, I've also noticed that some of these systems are being used in tunnels and I'm in very active designer of tunnel fire safety, being involved in many projects in Poland. So that one was really, really interesting to me because some people in my country were asking me about my opinions about the systems.

[00:00:56] Wojciech Wegrzynski: So I figured out there was the best way to learn something new about [00:01:00] them. watermist systems then inviting an expert into the podcast and just ask them. And as that's what I did, I found a really nice expert with a great experience in burning tunnels and extinguishing them with water mist, Mr. Johnny Jenssen from VID Fire Kill company from Denmark..

[00:01:19] Wojciech Wegrzynski: Johnny has done enormous, enormous fire tests in Spain to prove that he solution for watermist is a fit for purpose for a certain project in Singapore. And, he's got to tell me all about it, but we're also going to touch differences between sprinkler systems or how he calls them deluge systems.

[00:01:41] Wojciech Wegrzynski: And, Medium pressure or low pressure or high pressure water mist But this is not only about, extinguishing fires in tunnels or suppressing fires in tunnels. Is also quite an interesting talk about how large projects , are awarded, what you have [00:02:00] to go through to, to get such a huge project. , what amount of engineering goes into that? We also touched a little.

[00:02:07] Wojciech Wegrzynski: Practical stuff related to water mist, which for me was the most interesting, I guess, because I there's the knowledge I wanted to get from this episode. So I hope you're still with me and I hope you're interested in this topic. I promise it's good. It's, it's worth your time. And, even though it may be a little less fire science ish than usual, it's still a great lessons , on how fire safety systems in buildings and in tunnels work, which in my opinion is highly valuable. So without further ado, please welcome Johnny Jessen from VID and , let's jump into the episodes [00:03:00] Hello, welcome to Fire Science Show. I'm today with Johnny Jessen from VID Fire Kill Hey Johnny That's amazing to actually have an in-person interview for once after dozens of remote ones So happy to have you. What brings you here, business

[00:03:25] Johnny Jessen: business Yes So I'm working with infrastructure projects we are looking into a few projects here in Poland

[00:03:33] Wojciech Wegrzynski: that's fantastic I know there's so much happening around in here especially in the tunnel uh area and that's something I actually wanted to talk with you today. Myself I'm an engineer who works a lot with road tunnels And I've stumbled upon information that you've done some really huge fire experiments in tunnels with with your water mist technology

[00:03:53] Johnny Jessen: That is right Yeah So uh in 2018 uh in combination with winning a [00:04:00] big project in Uh one of the requirements in the tender was that we had to verify performance criteria as set by the client

[00:04:11] Wojciech Wegrzynski: Some weeks ago I have been in the watermist conference by IWMA and I've learned that's watermist people test everything by the trial of fire So somehow I am not surprised by the fact that you've burned the tunnel Uh if this technology is is working that has been the most fascinating aspect from connecting with the world of watermist for myself.

[00:04:36] Wojciech Wegrzynski: Before we start talking about tunnels I would like to talk a bit about the technology because I'm not sure if everyone in the audience is on the same page with us and I'm not sure if I'm on the same page For me uh sometime ago it was usually thinking about just what water based extinguishing systems I was not really that [00:05:00] looking into the differences between them but then I've obviously learned there is watermist there's sprinklers And then I've learned that that water mist flavors like low pressure high pressure, so if you could like briefly explain how does that differentiate between the solutions What what's the differences

[00:05:16] Johnny Jessen: So I think to uh Make it most simple So accordingly to a NFPA 750 So the definition between a sprinkler deluge system and the definition when it's becoming a water

[00:05:30] Wojciech Wegrzynski: Mister that's because

[00:05:33] Johnny Jessen: if you are distributing DB 90 meaning It's in your spray pattern meaning that your droplets is above one millimeter thousand microne

[00:05:43] Wojciech Wegrzynski: units

[00:05:44] Johnny Jessen: by definition a dilute system or a sprinkler system If it's below it's a water mist system and then it's correctly as you said there is high pressure There is intermediate pressure and there is low pressure and they of course have different droplet [00:06:00] distribution However part of the should we say the droplet this distribution is In a lot of varieties of droplets we're high pressure is very

[00:06:10] Wojciech Wegrzynski: very

[00:06:10] Johnny Jessen: efficient If you have as close compartment the machinery room where you really have high temperatures and Small droplets get into dang They will not be drafted away by ventilation

[00:06:22] Wojciech Wegrzynski: or Metro

[00:06:23] Johnny Jessen: wind then they immediately have an effect on the cool the fire Where on the opposite if you are in a to your application then of course the smaller droplets will be carried away either by a natural wind or by the ventilation system Then meaning that the smaller droplet will not come into action with a fire where you'll have a low pressure with this Should we say a hybrid between what I would call it tend to be a dilute system but at the same time also have the good droplet droplet distribution the smaller droplets like a high pressure system as well have

[00:06:57] Wojciech Wegrzynski: So it could be possible to simplify [00:07:00] it into a discussion that the bigger the droplet the easier it has to penetrate through hot air or smoke and it can easily reach the fire but the worst its capability to evaporate and take heat away Right

[00:07:14] Johnny Jessen: So th that's true We say total fundamental way of say mitigating a fire that is that a dilute system is a wetting Yeah So that's the main although it also a portion of the droplet we'll also a better rate

[00:07:27] Wojciech Wegrzynski: and

[00:07:27] Johnny Jessen: cool. A vice versa we've talked about a watermist system Then the most important and critical is the smaller

[00:07:36] Wojciech Wegrzynski: correct

[00:07:37] Johnny Jessen: droplet variation which will evaporate and cool it And a minor part will then act as a wetting medium As you said penetrates you to

[00:07:46] Wojciech Wegrzynski: by

[00:07:46] Johnny Jessen: effect or the fire flood as well also Yeah

[00:07:50] Wojciech Wegrzynski: And they've also always love the differences between like sprinkler system or automatic sprinklers and then the deluge systems And this is something that Hollywood[00:08:00] wrap their mind around because you always in the movies it's always like someone breaks a sprinkler and then everything on the floor operates there was for me the my favorite scene was from Blade movie where he turned the water in the tank into holy water and then sprinklered vampires And that was absolutely hilarious when he did that So in your case in tunnels We would pretty much always be talking about systems that have to have fire detection open nozzles and you just literally floods a section of a tunnel Otherwise it makes no sense so no bulbs no automatic operation it's that they will not work Now I've learned that already Yes okay cool

[00:08:42] Wojciech Wegrzynski: I think this introduction is helpful to understand the differences in technologies However Still the technology seemed to be very similar like the main action would be the cooling and the the the direct action on the fuel I think even if you have sprinkler systems which if not technically would penetrate [00:09:00] the plume I mean we're talking about And I just had Anja Hoffman in the podcast who's researching fires and vehicles and she told me that it's quite difficult to extinguish buses because they're waterproof So it's like they're men's to not be penetrated by the water So in Essence is the external action against the fire and products of the fire which is the important one Okay So let's go into the world of tunnels You say you have one a project overseas And one of the requirements was that you demonstrate your system's capability to be fit for the purpose Can you tell us First I'm really interested in how does one define an experiments to be a requirement for a commercial project Because in Europe I don't think I've ever been in such a situation that someone would and I'm not talking about standard tests which we do at ITB all the time all day long [00:10:00] but like experimental work too to show that solution is fit for design purpose

[00:10:05] Johnny Jessen: That is not totally correct because they have been. Sure You know watermist you say is not a technology which is 50 or 100 years old

[00:10:13] Wojciech Wegrzynski: So

[00:10:13] Johnny Jessen: it's what we call in our terms a relative new technology So in the start so talking about the eighties and nineties so

[00:10:21] Wojciech Wegrzynski: there

[00:10:21] Johnny Jessen: there was no shall we say a

[00:10:24] Wojciech Wegrzynski: based

[00:10:25] Johnny Jessen: or test perform the so-and-so some of the UK projects some of the big projects made in Spain and France Actually also was based on tender requirements where they had to

[00:10:36] Wojciech Wegrzynski: to

[00:10:37] Johnny Jessen: a full-scale test also.

[00:10:39] Wojciech Wegrzynski: But that is for watermist technology

[00:10:42] Wojciech Wegrzynski: Yes

[00:10:42] Wojciech Wegrzynski: And how word that the requirements defined in the

[00:10:44] Johnny Jessen: Yeah

[00:10:45] Wojciech Wegrzynski: for this particular

[00:10:45] Wojciech Wegrzynski: project

[00:10:46] Johnny Jessen: So I I not into detail but what I can explain is about the big experiment though The last

[00:10:51] Johnny Jessen: experiment that we did in Spain in 2018 So this is of course we are not typically not involved in the [00:11:00] protocols the basic criteria for living up to what the client wants So

[00:11:04] Wojciech Wegrzynski: that is

[00:11:05] Johnny Jessen: totally up to the authorities having jurisdiction and

[00:11:08] Wojciech Wegrzynski: and

[00:11:08] Johnny Jessen: and choose a local stakeholders and in this case it was in Singapore it was civil defense was very much involved in that And how did they then Create the protocol So they of course hire authority fire lab certified fire lab Gala with them to create the protocol

[00:11:29] Wojciech Wegrzynski: by by protocol you mean a certain experiment to be carried to

[00:11:33] Johnny Jessen: Yes

[00:11:33] Wojciech Wegrzynski: And what what

[00:11:34] Johnny Jessen: is the criteria and then

[00:11:36] Wojciech Wegrzynski: yeah

[00:11:36] Johnny Jessen: actually Yeah So in our case so Effectis was hired by the tunnel owner This wasn't that case was LTA which is typically the same as you would have a Polish highways or something like that They wrote to authorities Of course you will try also to find some

[00:11:54] Wojciech Wegrzynski: global or

[00:11:55] Johnny Jessen: requirements which can be used to put into the specification of [00:12:00] the fire test And in this case it was important for them was besides through say the engineering part was the tenability requirements and Particular case they was referring to NFPA 5 0 2 which has the tunnel and the bridge specification regarding to the ability So there is certain tenability requirements regarding criteria and downstream temperatures and so on and so on However set up of the fire load the fuel set up and so on It's nothing that you will find in NFPA 5 0 2 So that is typically either totally developed by the file lab in combination with the authorities local authorities or referring to one of the most common used guidance which could be SOLIT or it could be opt UpTun we have should we say special part for setting up a fire test and protocols for full-scale uh [00:13:00] tunnel fire

[00:13:00] Wojciech Wegrzynski: So you had a certain criteria defined for tenability which were related to visibility, temperature, heat fluxes and so on which were the target to obtain And then to demonstrate the capacity of this technology you had to compare it with an extinguished fire right

[00:13:17] Johnny Jessen: yeah Typically to do what we call free fires

[00:13:21] Wojciech Wegrzynski: it's very very

[00:13:22] Johnny Jessen: to be allowed to do in a test tunnel

[00:13:26] Wojciech Wegrzynski: Yeah

[00:13:26] Johnny Jessen: but anyhow I think for the first and last time we were allowed to do with because I will tell you what happened with that

[00:13:35] Wojciech Wegrzynski: but I think maybe the

[00:13:37] Johnny Jessen: actual tests that we did And then I will go back to

[00:13:40] Wojciech Wegrzynski: the to the

[00:13:41] Johnny Jessen: free fire because that's some interesting aspects in that Yeah

[00:13:44] Wojciech Wegrzynski: Okay So to start with we to test so first before you've mentioned when we discussed this you've mentioned that a deluge system would be commonly applied for such a tunnel in this

[00:13:55] Wojciech Wegrzynski: region

[00:13:56] Johnny Jessen: this region

[00:13:57] Wojciech Wegrzynski: So can you first tell me how it happened that [00:14:00] you propose the mist and in place of that And and then tell me about themist tests

[00:14:05] Johnny Jessen: So of course as I was mentioning Referring back to the eighties to the nineties a lot of experiments was done with the water mist also in tunnel application So if you go a little bit more back in the history eh countries like Japan like Australia and a few other also the states uh United States actually the last 50 to 75 years actually implemented deluge system into their tunnel systems So for them it's not a new technology So you can say that in those part they've was leaning to what was done in Australia and Japan So that is also was implemented to Vietnam to Singapore and the other countries of course. So there was no she would say in brackets need to look for new technologies but of course When you get new technology if it's have a efficient engineering part maybe and less water consumption power consumption And so on Then of [00:15:00] course this also get into the in this particular case with reference to this project in Singapore watermist was interested for the client because it was a refurbishment of existing tunnels So actually two different channel systems totally 14 kilometer times two tubes So

[00:15:19] Wojciech Wegrzynski: 20

[00:15:20] Johnny Jessen: I never said it was roughly 30 kilometers of tunnels which had to be re refurbished So it was in the past it was not say installed with any kind of active Fire suppression but as we all know that if you have an existing tunnel system you also have a drainage capacity And for that it was a very large problem for the client that if they want to introduce a deluge system into the existing channels yeah Then the drainage capacity could simply not

[00:15:50] Wojciech Wegrzynski: say

[00:15:50] Johnny Jessen: the water consumption that by activation Yeah by the dilute system So that's why to be honest probably watermist also for them was [00:16:00] interesting The other aspect is of course that they didn't want a system or technology with Not as efficient as a

[00:16:06] Wojciech Wegrzynski: new

[00:16:06] Johnny Jessen: system And that's why I think coming back to why was the in the specification in the tender specification that demand for doing full-scale test and also actually comparison test with deluge system and a mixed system to see if the efficiency was the same as for a deluge syste,. So I think that was the basis of

[00:16:28] Wojciech Wegrzynski: why

[00:16:29] Johnny Jessen: we

[00:16:29] Wojciech Wegrzynski: got

[00:16:29] Johnny Jessen: into that project

[00:16:31] Wojciech Wegrzynski: If you compare the deluge systems and water systems usually discussing their economical benefits it's usually comes down to water consumption uh because you need less water

[00:16:44] Johnny Jessen: We have to define I'll be talking about a high pressure low pressure or deluge because there is Yeah it is Yeah Yeah So as I mentioned in the in the introduction onto the start that a low pressure water mist system [00:17:00] More kind of a hybrid with a dilution system So it

[00:17:03] Wojciech Wegrzynski: have

[00:17:04] Johnny Jessen: for instance the pressure level is in PSI 16 everything is P and 16 mean maximum 16 bar

[00:17:10] Wojciech Wegrzynski: So

[00:17:11] Johnny Jessen: mean we on the same pressure level as a swing lower dilutions them So that means that pipes pumps are very much similar to what you will find in a deluge system

[00:17:20] Wojciech Wegrzynski: okay And for high pressure you would need

[00:17:22] Wojciech Wegrzynski: a

[00:17:23] Johnny Jessen: you'll have high

[00:17:23] Wojciech Wegrzynski: specific

[00:17:25] Johnny Jessen: Yeah

[00:17:25] Wojciech Wegrzynski: but then also much less

[00:17:26] Wojciech Wegrzynski: water

[00:17:27] Johnny Jessen: So also power again the power consumption from a low pressure is very similar to what you would experience with a deluge system However if you have power from a high pressure system it will minimum be double or triple the power consumption from a dilute or a low pressure

[00:17:45] Wojciech Wegrzynski: system

[00:17:46] Johnny Jessen: Yeah Talking about the water consumption So a deluge system So if we take high pressure low pressure is similar density So uh all from 2.5 millimeter PEM per minute to [00:18:00] 4.5 millimeter per minute all depending on the application

[00:18:03] Wojciech Wegrzynski: So there's also like two and a half or four and a half liters per minute per square meter right

[00:18:08] Johnny Jessen: Yeah that's correct If you compare that with a deluge system and now you say referring to in the region where what this system or this application was so there's typically deluge which is 10 millimeter per minute to 12 millimeter per minute And I also was the two different systems that we was bound to test as well also affect his was bound to test in in

[00:18:32] Johnny Jessen: combination Yeah And I

[00:18:33] Wojciech Wegrzynski: asked that because whenever I have a discussion with a client regarding installment of fixed extinguishing systems in the tunnels

[00:18:40] Johnny Jessen: Yeah

[00:18:40] Wojciech Wegrzynski: and I think out of like 20 tunnels we've been involved in Poland the fixed were considered or put in the tender I think three of them and you know the discussion rarely goes into kinetic energy of droplets or the capability of them to penetrate things or stuff like that It [00:19:00] usually goes okay But how much water how big the tank uh The power of the pumps that we need can we remove the water from there Will it be contaminated How do we clean it You know these are the things that the clients are mostly

[00:19:14] Johnny Jessen: concerned about

[00:19:15] Wojciech Wegrzynski: because in the end I guess they assumed that the capability of the system to fight fire is It's similar and it's just provided by the technology So so we rarely go into discussions where the one system is capable of extinguishing or not but rather into the functional aspects of what it means to have the systems on the tunnel

[00:19:38] Johnny Jessen: Coming back to the tree most common technologies installed in so-and-so low pressure high pressure or deluge So also again there and that is concern is of course you say contamination and all the faces blocked by dirt and so on And they also again there The difference is that as you know the way that high pressure is distributing [00:20:00] the droplets is by pressure mainly

[00:20:02] Wojciech Wegrzynski: by

[00:20:02] Johnny Jessen: the high pressure which is then distribute it those variet of droplet sizes wherever a low pressure system it's again a little bit as a as I mentioned the hybrid with the new system accelerating the water before it went out of her What should we say orifice and the orifices that we use in our streets say a tunnel is between Depending on what application and system a model that we are between two and a half to four millimeters And then you have to bear in mind A high-pressure system is between open two to oh 0.4 millimeter

[00:20:37] Wojciech Wegrzynski: of

[00:20:37] Johnny Jessen: it's a much more vulnurable contamination from the outside but for sure from the inside

[00:20:43] Wojciech Wegrzynski: So so the maintenance would be a factor as well I'm I'm surprised actually maintenance is not not that often being brought up by the people who will buy and use the tunnel for the next 50 years And actually they probably should ask that as the [00:21:00] first question how much I've also um in in sometimes in Poland we had foam systems

[00:21:05] Johnny Jessen: yes

[00:21:06] Wojciech Wegrzynski: Uh we even had a CAFS compressed form a system designed for one tunnel so there's a large group of active systems that fill more or less the same purpose but with completely different ways Okay So your client was interested in refurbishing a tunnel existing tunnel for which they seem that a more let's say cost effective or a different solution as in water mist would be sufficient I don't want to say better than deluge system because all the systems fit different needs Right But but they found that watermistis potentially a vialable technology They've asked you to uh to provide the proof in terms of experiments So okay How does one like go from okay Yeah boss we got it We got the project We just need to burn the tunnel How do you communicate [00:22:00] that to your leadership and how do you perform

[00:22:02] Johnny Jessen: No So I mean it was a it was not a surprise for the leadership

[00:22:07] Wojciech Wegrzynski: because

[00:22:07] Johnny Jessen: as I told you that in the tender re

[00:22:09] Wojciech Wegrzynski: requirements

[00:22:10] Johnny Jessen: when we made our offer then it was clear to us and we had to

[00:22:14] Wojciech Wegrzynski: Okay So okay So sorry

[00:22:16] Johnny Jessen: it was not a big shock for my boss

[00:22:18] Wojciech Wegrzynski: Let me rephrase that Okay Okay boss We can apply for this tender but we need to first find the tunnel to burn down So it is more like this decision. So how does one approach that

[00:22:29] Johnny Jessen: So uh then of course you should they actually we talk about European The two most common used test tunnels in Europe there is the in Norway

[00:22:40] Wojciech Wegrzynski: which is

[00:22:41] Johnny Jessen: an abandoned road tunnel And then there is the tunnel in this San Pedro the which is in Asturias in Spain with this an abandoned railway tunnel which then is refurbished to be a road on social

[00:22:55] Wojciech Wegrzynski: So

[00:22:55] Johnny Jessen: to speak Yeah 600 meter long term sort of course You go [00:23:00] into communication with the with the guys in Spain and then could be borough Actually it costs something Of course

[00:23:07] Wojciech Wegrzynski: I can imagine

[00:23:08] Johnny Jessen: Yeah Eh do you have some way of time in 2018 for the shop and then they will answer how much time do you need Yes we need to do 16 test sprints Yeah So that was the estimation actually that we had to perform tests to go through all the parameters that the client wants to have verified

[00:23:31] Wojciech Wegrzynski: 16

[00:23:32] Johnny Jessen: 16

[00:23:32] Wojciech Wegrzynski: Okay And can you briefly tell us the scope of the tests from the report I've received from VID I saw there was a free burn tests There was two water mist tests right Can you tell us uh more in details about

[00:23:46] Wojciech Wegrzynski: uh

[00:23:47] Johnny Jessen: there was a lot of combination tests with we cannot go into too today

[00:23:51] Wojciech Wegrzynski: because

[00:23:52] Johnny Jessen: will be to complex But as you say that you said you

[00:23:56] Wojciech Wegrzynski: realized

[00:23:56] Johnny Jessen: that watermist they do a lot of actual tests [00:24:00]

[00:24:00] Wojciech Wegrzynski: practical

[00:24:00] Johnny Jessen: test word deluge or spring the system Yeah they have the base behind them so they can typically in a lot of projects and also accordingly to the regulation go directly So they allowed

[00:24:12] Wojciech Wegrzynski: in many

[00:24:13] Johnny Jessen: To do it without doing that she will test So first of all you could say that we had to calibrate for this test tunnel in relation to what we want to achieve Actually pre-test is the complex thing And this is the thing which takes most the majority of the time when you are into a testimony and the actual final test Press the bottom and you

[00:24:38] Wojciech Wegrzynski: invite the

[00:24:39] Johnny Jessen: client to come and see the actual test and performance That's the smallest part Let me put it this way Yeah Yeah

[00:24:46] Wojciech Wegrzynski: So the pre-test is when you calibrate the fuel source And so stuff like that

[00:24:49] Johnny Jessen: not so much the fuel source because that was a given she was

[00:24:52] Wojciech Wegrzynski: that was for the fine Okay

[00:24:54] Johnny Jessen: But there was a lot of other calibration and also instrumentation which had

[00:24:59] Wojciech Wegrzynski: to be

[00:24:59] Johnny Jessen: [00:25:00] calibrated and so on Yeah

[00:25:01] Wojciech Wegrzynski: what was the fuel source

[00:25:03] Johnny Jessen: Coming back to if they're those existing channels in Singapore So at the point in 2018 there was not allowed any heavy goods vehicles to go through this tunnel So the maximum fire load allowed to go into the channels was a hundred megabit Yeah So that means a lot of the goods which have to be transported from one end to the other end of the city had to go a very very Deviation to get to the punch So why they want to install or implement a fixed firefighting systems was To allow heavy goods vehicles with the potentially say more dangerous there's loads to go through And also they have had not very nice fire accidents in those tunnels also during the year So it was true things that they want to uh knock by doing this Yeah So then of course the next question is that how uh big loads are the Get the client expect to go through channels And of course there you can go [00:26:00] into a research say what you will find to be done in the past of what is the typically file load of heavy goods vehicle depending on the load and so on But anyway the clients that we want to go for very high fuel loads because we want Also to build for the future Meaning that potential

[00:26:19] Wojciech Wegrzynski: bigger

[00:26:20] Johnny Jessen: loads can go through those tunnels

[00:26:22] Wojciech Wegrzynski: yeah In in the technical documentation they see it was a lot of stacks of wood and then plastic pallettes

[00:26:29] Johnny Jessen: You can say why are you using plastics and why are using palace actually as the fuel

[00:26:35] Wojciech Wegrzynski: So you are doing

[00:26:36] Johnny Jessen: Those kinds of tests and you also have to be compared with a competitors so to speak

[00:26:43] Wojciech Wegrzynski: So

[00:26:43] Johnny Jessen: whatever you see our competition doing a similar type of test you will see the same fuel So that is a generally accepted fuel mix because it's replicable That means that Euro pallet whatever it's bought in Poland [00:27:00] or it's bought in

[00:27:00] Wojciech Wegrzynski: Denmark

[00:27:01] Johnny Jessen: or moved to Singapore whatever it's having the same dimensions the same wood

[00:27:07] Wojciech Wegrzynski: Mass and stuff like that Exactly Yeah

[00:27:10] Wojciech Wegrzynski: And it's also

[00:27:11] Johnny Jessen: identified what is the Fire capacity within one pallet So it's very easy to build up different fire loads with w

[00:27:19] Wojciech Wegrzynski: Yeah I understand the choice because we usually sought to working with wood cribs as well in in buildings

[00:27:25] Johnny Jessen: So I can tell you that if you go 15 20 years ago there was a lot of experiments done with actual vehicles and also with with the heavy goods vehicles But the problem by that is that you cannot replicate so that

[00:27:39] Wojciech Wegrzynski: if it's a Japanese

[00:27:40] Johnny Jessen: car it's a European car You'll

[00:27:41] Wojciech Wegrzynski: have

[00:27:42] Johnny Jessen: the the content of plastic and

[00:27:44] Wojciech Wegrzynski: And they're also not representative for years So because you would probably purchase an older vehicle not in necessarily a fresh new from the dealership and and stuff like that That's it's also that's also a thing I've discussed with Anja Boelinghaus Hoffman three episodes ago It's a [00:28:00] testing buses and and all these things were very important that the age of the vehicle and what the material contents of the vehicle inside is However here we are I think the biggest challenges with the cargo The vehicle itself like if you've burned an empty truck in the tunnel it should not be that horrible And when it's filled with cargo it's completely different And I also saw that you've covered The font in the back with the metal sheets the sides with uh some kind of a cloth uh that that probably burnt

[00:28:28] Wojciech Wegrzynski: out

[00:28:29] Johnny Jessen: if you look some of the experiments which was done in the early 2002 2010 or 12 then you will see a lot of those experiments was done with what you call open file loss That mean there was not shoes had covered with Taplin or with a metal sheet And that means It's much more easier to uh to suppress say an open fire and that's why today you'll see in all new full-scale tests whatever is performed by deluge or by a different [00:29:00] watermista windows you will see always it will be trying to simulate a real situation and a real goods vehicle

[00:29:07] Wojciech Wegrzynski: From your perspective is opposite You need the top covered because we don't want to have artificial cooling of the fuel inside by by spraying water on top of it But I also remember a talk I think it was professor Ingasson in Austrian Graz at some point who said that The the ventilation conditions on of the fuel have immense effects on on on the size of the fire

[00:29:31] Wojciech Wegrzynski: And you could you could burn two vehicles of that one to 50 megawatts one to few hundred megawatts just by altering how it's shielded and uncovered And also had this episode of the show with Sarah McAllister Who's burning crips passionately And she's burned hundreds if not thousands of wood cribs and investigates the differences of how the porosity affects the burning insights So so definitely the the fuel is very complex itself but okay Let's assume this is [00:30:00] standardized so now to the results Like what what was the main difference Obviously the extinguishing must have

[00:30:06] Wojciech Wegrzynski: had an

[00:30:07] Johnny Jessen: thing I first I want

[00:30:08] Johnny Jessen: just to say just a few brief words about the protocol typically when you have a fire in a tunnel you will try to activate your system as soon as possible to attack the fire in this initial stage But again typically if you refer back to more or less all experiments done with whatever it's dilute or water mist systems you will see a delayed activation And it typically should be period before you will activate your system is either when the temperature reads 60 degrees or it will just with a certain time limit In our case So when 60 degrees was rich then the fire was detected And from that point fire detected then in the protocol we had to wait minimum five minutes before he was

[00:30:56] Wojciech Wegrzynski: allowed

[00:30:57] Johnny Jessen: to

[00:30:57] Wojciech Wegrzynski: activate

[00:30:57] Johnny Jessen: the system which will [00:31:00] typically not be the actual case because if identified fire either bio detection system or your CCTV system of course you will activate your system to attack the fire its initial state But here we let

[00:31:13] Wojciech Wegrzynski: it grow

[00:31:14] Johnny Jessen: actually you can say all those windows which actually performed a full scale testing build into say kind of a safe extra additional safety factor And of course

[00:31:25] Wojciech Wegrzynski: you also

[00:31:26] Johnny Jessen: in some of the fire strategies in the tunnel you will also see that the authorities want to say a kind of a delay also from a fire detected until System is activated allowing people to evacuate out of the tunnel So that could be a timeframe of two to three minutes

[00:31:45] Wojciech Wegrzynski: it was also carried in a ventilation conditions So it was the ventilation triggered immediately or also delayed together with your

[00:31:52] Wojciech Wegrzynski: system

[00:31:53] Johnny Jessen: in this particular case and in Singapore

[00:31:56] Wojciech Wegrzynski: local

[00:31:57] Johnny Jessen: regulation that they all the [00:32:00] time whatever you have a fire not a fire all the 24 7 they run with a five meters per second installation

[00:32:07] Wojciech Wegrzynski: So it's like the initial condition for

[00:32:09] Wojciech Wegrzynski: everything Yeah

[00:32:10] Johnny Jessen: So that means during the whole phase we had five meters per meter running all the time

[00:32:16] Wojciech Wegrzynski: So you've let the fire grow for let's say seven eight minutes I assume

[00:32:21] Johnny Jessen: Yeah No you'll you to take the fire detection of

[00:32:25] Wojciech Wegrzynski: the fire So to speak

[00:32:27] Johnny Jessen: can say Yeah And from that

[00:32:29] Wojciech Wegrzynski: five

[00:32:29] Johnny Jessen: minutes before you allow to activate

[00:32:32] Wojciech Wegrzynski: and what happens upon activation is the effect like immediate does it take you some time how does it look with the moment you use start the system

[00:32:42] Johnny Jessen: So uh especially within visualization and smoke a lot of smoke system but of course whatever it's a dilute system or water mist system until you have penetration to say through the toppling sites

[00:32:56] Wojciech Wegrzynski: of this

[00:32:57] Johnny Jessen: heavy goods vehicles until [00:33:00] So you only cool the

[00:33:02] Wojciech Wegrzynski: So

[00:33:02] Johnny Jessen: until you have direct access into the fireside yard then uh but you will see a lot of steam You'll see a lot of smoke there Yeah

[00:33:10] Wojciech Wegrzynski: I'm asking because from the plots I see the the spike in radiation and uh rapid change in the in the right red it hit flux and it's also something which is my own feeling when I They with with any extinguishing systems that if you if you are actually The source of fire And I assume in your laboratory when you do protocols you feel that as well the moment this device is activated is like someone turned off radiation It's like

[00:33:38] Johnny Jessen: yeah And

[00:33:38] Wojciech Wegrzynski: gone it's amazing How extremely well water is in shielding from radiation And I assume that is the biggest effect that it can have on the life life safety ahead of the fire So I assumed the moment that the water released and the courses of two tests have completely disjoint So so In the free burn test which [00:34:00] I see the peak heat release rate reached at 233 megawatts That is a lot of heat release Yeah

[00:34:08] Johnny Jessen: The most frightening here I think is the speed within it it res

[00:34:13] Wojciech Wegrzynski: so that I always what

[00:34:15] Johnny Jessen: I'm referring to discussion with consultants

[00:34:17] Wojciech Wegrzynski: or

[00:34:18] Johnny Jessen: owners that as we all know that 95% of all tunnels whatever is in Europe

[00:34:23] Wojciech Wegrzynski: or

[00:34:24] Johnny Jessen: globally is depending on a ventilation system to to do the job so to speak but here you can see that the ventilation system the only thing that it actually Performed was up to the tenability requirement Meaning the upstream

[00:34:38] Wojciech Wegrzynski: it's an

[00:34:39] Johnny Jessen: was done but

[00:34:41] Wojciech Wegrzynski: All the

[00:34:41] Johnny Jessen: parameters and then coming back to why but ever never be allowed more to do a free free burn in a in a test one So actually we destroyed 150 meters of the tunnel there Oh Uh very unfortunately uh so they told us very [00:35:00] specifically if ever again B should come there

[00:35:02] Wojciech Wegrzynski: not actually

[00:35:03] Johnny Jessen: to us directly because it was effective Who

[00:35:06] Wojciech Wegrzynski: on our

[00:35:06] Johnny Jessen: behalf was Yeah hiring the on the client's behalf I was hiring the the chance that it will ever never be allowed anymore do a free burn. So probably we will be the last tunnel winner who will be allowed to do a free burn But I mean now

[00:35:22] Wojciech Wegrzynski: test can be used as reference I assume you would be kind enough if someone wants to

[00:35:27] Johnny Jessen: I

[00:35:28] Wojciech Wegrzynski: I

[00:35:28] Johnny Jessen: the Wojciech is very much coming back to what you say that the ventilation velocity have a lot of

[00:35:33] Wojciech Wegrzynski: effort

[00:35:34] Johnny Jessen: on the firewall My thesis there is that if it was been running with the critical velocity for that then you will not have have that gross potential So it will have been delayed much much more also for the test situations where our system was if it was not performed with five meters per second Two or two and a half meters depending on what was the calculated critical velocity you will [00:36:00] see a much more critical or dramatic gross fire gross rate as you see on those experiments

[00:36:06] Wojciech Wegrzynski: I I think it was the clearest it shown it was when experiments carried in Gent for the Flanders government It was experiments run by Xavier Deckers and the university of Gent. What they've done they've built a tunnel from marine containers and they were burning vehicles inside these containers a lot I think it was in double digits I don't recall the The final number of how many costs they've burned but it was a lot and they were playing with ventilation and the different extinguishing systems And they did found that when it was ventilation alone it had a huge effect on the size of the fire When it was the extinguishing system alone it had this Effect of penetrating the vehicle and actually affecting the size of the fire which was in a way surprising because we're talking [00:37:00] about close

[00:37:00] Wojciech Wegrzynski: cars and they also found When it was a combination of ventilation and suppression this effect was not really observed that when uh when the forced ventilation was there it still has grown to quite a considerable size the extinguishing system did its part It did it did lower the temperatures and everything but they observed the size of the fire was still growing because the fact that you have pushed the air inside maybe I should invite him for an episode because I found that the research

[00:37:34] Johnny Jessen: just just one comment to that And I think that is Generally not observed in results And also the aftermath of the result is that when you do your heat release rate in those experiments it's typically is the chemical heat release that you

[00:37:48] Wojciech Wegrzynski: are seeing So

[00:37:49] Johnny Jessen: that means it's consumption of

[00:37:51] Wojciech Wegrzynski: oxygen

[00:37:52] Johnny Jessen: yeah Of oxygen Yeah But this is what I would call telling something about the fire machine I mean

[00:37:57] Wojciech Wegrzynski: that

[00:37:58] Johnny Jessen: in

[00:37:58] Wojciech Wegrzynski: the

[00:37:58] Johnny Jessen: of the fire it's [00:38:00] not actually telling anything outside the center of the fire

[00:38:04] Wojciech Wegrzynski: So

[00:38:04] Johnny Jessen: for me in a single source should be for channel owners and stakeholders should be more interesting to look at the convective heat release rate And also if you look at the report that

[00:38:15] Wojciech Wegrzynski: that

[00:38:15] Johnny Jessen: I did there if you look at Temperatures outside what I would call the fire machine so to speak Then you receive they are relatively low I think in this case a 59 megawatt fire temperature

[00:38:28] Wojciech Wegrzynski: Yeah So so the chemical release was around 50 megawatts in in your in your water sprayed

[00:38:33] Wojciech Wegrzynski: test

[00:38:34] Johnny Jessen: look just outside the center of the fire quite low temperatures

[00:38:38] Wojciech Wegrzynski: which makes sense because you're very effectively even though the heat is released

[00:38:43] Wojciech Wegrzynski: to the

[00:38:43] Johnny Jessen: it's not you say reflecting the jet fence or ventilation system which is installed in tunnels that they don't take that aspect fully into consideration

[00:38:52] Wojciech Wegrzynski: Okay Now I have to ask you two questions related to myths about a water

[00:38:59] Johnny Jessen: Yeah

[00:38:59] Wojciech Wegrzynski: [00:39:00] I am often facing when I'm discussing the technologies with stakeholders one is that the combination of water mist and the ventilation that the water mist will be carried away from the fire by the ventilation itself And you had very strong ventilation in here because five meters per second is way above the critical velocities which we would calculate usually so so what's your take Did you observe any uh negative interference between ventilation watermist in your case

[00:39:33] Johnny Jessen: From my perspective I would say it's a little bit overrated this deviation aspects You will see I mean if you physically look at the display impact the mutilation on

[00:39:43] Wojciech Wegrzynski: this you

[00:39:44] Johnny Jessen: have a deviation Yeah But it's minor Oh yeah Probably for low pressure dilute system It's definitely a minor deviation but why I think More or less relevant is that typically here in Europe when we when you do fire suppression [00:40:00] systems and channel you're

[00:40:01] Wojciech Wegrzynski: all that

[00:40:01] Johnny Jessen: building that on a on a tree So strategy meaning that you have your middle zone but you have your

[00:40:07] Wojciech Wegrzynski: fire

[00:40:07] Johnny Jessen: but you activate upstream and you activate downstream

[00:40:11] Wojciech Wegrzynski: So you make sure that the fire is more less in the middle of the of the

[00:40:14] Johnny Jessen: So that means that even if you have Some effect by high velocities from the ventilation system but that also mean that you will move your fire in the same direction

[00:40:24] Wojciech Wegrzynski: So

[00:40:24] Wojciech Wegrzynski: the water will meet the fire wherever the

[00:40:27] Wojciech Wegrzynski: ventilation make them go Okay

[00:40:29] Johnny Jessen: doesn't have any effect on the capability of the irrespectively if it's a high pressure system or it's a low pressure deluge system Yeah

[00:40:37] Wojciech Wegrzynski: And the the second one comes I think more from foam industry may be if you have an accident where the fuel is not necessarily on the top of the vehicle but it's sort of spillage what extent this technology would would still work with a pool fire as we are perfectly aware that that it has no way to interfere with the fuel surface at all [00:41:00] Right So so

[00:41:01] Johnny Jessen: yeah So then we have differentiate between a deluge system attacking a pool fire or is a water mist

[00:41:09] Wojciech Wegrzynski: Steve checking

[00:41:10] Johnny Jessen: a pool fire However talking about a water mist Solution attacking a pool fi is very efficient and even more efficient than the a deluge system

[00:41:21] Wojciech Wegrzynski: and

[00:41:21] Johnny Jessen: as efficient that's you say I came as efficient as a foam Even the pickup the fuel spillage is you more efficient It is You have immediately I mean really immediately

[00:41:34] Wojciech Wegrzynski: within

[00:41:35] Johnny Jessen: activate the system You will have such a proration factor that you you have to see it's totally absorbed And

[00:41:43] Wojciech Wegrzynski: we

[00:41:43] Johnny Jessen: did some in coming back to the test that we did in uh Where we did a fuel spillage pool fires up to 30 or 40 megabits fires And within two minutes it was totally extinguished

[00:41:56] Wojciech Wegrzynski: Extinguished

[00:41:57] Johnny Jessen: extinguished even extinguished Yeah But that means [00:42:00] that smaller fuel spillage

[00:42:02] Wojciech Wegrzynski: you don't get

[00:42:02] Johnny Jessen: that big evaporation FX So it take a little bit longer time. Of course we know that a foam it will

[00:42:08] Johnny Jessen: totally I isolate But I mean if you I have seen some American research I will fight that research for you You will see they try to compare the extinct race time between firm's systems mixed foam water mist systems and bottom is systems

[00:42:24] Wojciech Wegrzynski: And

[00:42:25] Johnny Jessen: it's minor differences I mean really really minor differences

[00:42:29] Wojciech Wegrzynski: yeah Uh I have one more mythF what about the visibility. Have you observed any effects related to the loss of visibility in the extinguishing green

[00:42:37] Johnny Jessen: So also again then you have to lean up to some specifications or requirements Also again here we lean up to all

[00:42:46] Wojciech Wegrzynski: File I've

[00:42:47] Johnny Jessen: up to what she say is accepted in the NFPA 5 0 2 where you have to say firearms or lamp poles within a certain distance have to be visible meaning that

[00:42:58] Wojciech Wegrzynski: you

[00:42:59] Johnny Jessen: see exit [00:43:00] signs and so on And we performed very well as you can Probably I don't know if you can see in

[00:43:04] Wojciech Wegrzynski: that

[00:43:05] Wojciech Wegrzynski: region

[00:43:05] Johnny Jessen: but then in not a report you can see that Yeah

[00:43:09] Wojciech Wegrzynski: is a part of evaluation

[00:43:11] Wojciech Wegrzynski: If

[00:43:11] Johnny Jessen: you look When we do videos when we activate the system you can do that for a deluge system You can do that for a water mist system And of course there there is some slight difference between a high pressure and a low

[00:43:26] Wojciech Wegrzynski: pressure

[00:43:26] Johnny Jessen: because of the tents that small droplets will make it a little bit more she would say yeah tends to look into but you will see people downstream 50 meters easily So for sure it will live up to the requirements whatever is within in FPA 5 0 2 for sure

[00:43:43] Wojciech Wegrzynski: Okay I think it's important too to talk about this you know myths because it's always being dropped in the middle of the discussion as a aha moment Okay But we will not see a the technology is great but you will not see anything so it's cannot be used

[00:43:58] Wojciech Wegrzynski: So

[00:43:58] Johnny Jessen: I mean also then [00:44:00] also you again you have to look into the practical So how is the fire strategy implemented into channels Typically you would you could of course have people into the channel when you activate the system But what you will try to attend this People who are out of the terms before that you will activate your system That's the typical

[00:44:18] Wojciech Wegrzynski: with

[00:44:18] Wojciech Wegrzynski: uh

[00:44:19] Johnny Jessen: I would say

[00:44:20] Wojciech Wegrzynski: I usually tell them I would rather be wet and with bad visibility then exposed to 250 megawatts that I I mean if I had the choice I would rather be wet than burn down

[00:44:31] Wojciech Wegrzynski: Yeah Okay Johnny I'm very thankful for sharing your views on this important subject And you also armed me up for better discussions with my local authorities uh uh for the future attended projects because I see immense value in in using active fire systems in tunnels to reduce the risks I'm also very In a way happy and and surprise We've mostly talked about life safety because from our perspective usually the extinguishing systems are [00:45:00] part of the safety of the building or structural safety or the money aspects not necessarily life safety but I'm I'm happy that your research was very life safety oriented And are there some resources available publicly that people could read up or watch

[00:45:14] Johnny Jessen: yeah for sure

[00:45:15] Wojciech Wegrzynski: there was a webinar

[00:45:16] Wojciech Wegrzynski: right

[00:45:16] Johnny Jessen: Yeah for sure We that's part of our company policy We have nothing to hide I mean and

[00:45:22] Wojciech Wegrzynski: all the

[00:45:22] Johnny Jessen: research that we do uh we put that public If

[00:45:26] Wojciech Wegrzynski: go into

[00:45:27] Johnny Jessen: our websites or to the LinkedIn website probably is the better one because

[00:45:32] Wojciech Wegrzynski: I

[00:45:32] Johnny Jessen: have released a lot of reports and posts there

[00:45:35] Wojciech Wegrzynski: regarding

[00:45:36] Johnny Jessen: the tissue looking for temperature in LinkedIn then they will find the good material

[00:45:42] Wojciech Wegrzynski: I will search for that and put that in the show notes So the audience can just go there with one click and share the resources And I'm from what I've saw it's worth spending a few minutes of your time taking a look in into them They were very interesting Johnny Thank you so much for coming to the Fire Science [00:46:00] Show in person that I appreciate that a lot and yeah All the best Thank you so much

[00:46:06] Johnny Jessen: pleasure to be part of it

[00:46:08] Wojciech Wegrzynski: And that's it. It was a great experience for me. Not only because I've learned so much watermist systems in tunnels, but also whole process of recording. This episode was fantastic. As Johnny has visited me in my office, and I had a very rare chance to make your life interview. And I prefer it very much over online it's much easier and such a better contact with the guests to, Inside your office and just discuss fire.

[00:46:34] Wojciech Wegrzynski: From the episode itself. The interesting part for me was the discussion about the ventilation and the fact that it was accounted for in the experiments. It's very important to have ventilation effects accounted for in any tunnel experiment. And they did. It was astounding learn that their heat release rate was 250 megawatts.

[00:46:53] Wojciech Wegrzynski: That's a huge fire. And, it actually led to the destruction of the tunnel, where they were doing their experiments, which is probably not that funny, [00:47:00] but yeah, that's, that's what huge fires do. It's great that we can actually do that in a controlled environment, measure that, and then, learn new things.

[00:47:09] Wojciech Wegrzynski: Even from let's say, catastrophic fire tests. It was also very interesting when he mentioned the differences between the chemical heat release rate and it was being transported. And that that's really powerful one because you know, the chemical huge release rate is what the fire emits when the things burn.

[00:47:24] Wojciech Wegrzynski: He was so focused on the convective heat transfer outside of the immediate zone where the fire is located. So how much heat actually goes to the left and the right of the tunnel when the fire is burning and, they've observed insane reductions in the heat release rates. So it means that maybe the chemistry of the fire was quenched to like 50 megawatts, maybe not completely, but the amount of heat that the fire actually.

[00:47:50] Wojciech Wegrzynski: Released into the tunnel was removed by a factor of 10 or maybe even 20. And I find it as an immense gain with the, with the proposed [00:48:00] system. Johnny has also mentioned some engineering guidelines, like SOLIT that can be used to design. Systems or experiments, I'll try to link them. He also has some resources which have already received.

[00:48:13] Wojciech Wegrzynski: So I'll try to share them with you. And I hope you found it interesting to learn a bit about watermist and extinguishing a big fires and tunnels for me, it was very worth my time. I hope that the same for you. So for today, that's it. And next week, we're going to have the last episode of this year. Because afterwards I will be going for a two week break, a planned Christmas break with the family.

[00:48:37] Wojciech Wegrzynski: You need to recharge a bit. So yeah, a kind of a Christmas episodes next week, maybe even less fire science'ish, but I hope more fun for you. So you don't want to miss that one and yeah. See you next Wednesday. Bye.