083 - Fire fundamentals pt 1 - Combustion and flame with Rory Hadden

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<v Wojciech Wegrzynski>Hello everybody! The welcome to the fire science show.

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<v Wojciech Wegrzynski>Happy new year.

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<v Wojciech Wegrzynski>Welcome to year 2023.

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<v Wojciech Wegrzynski>I hope it's a great year for you.

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<v Wojciech Wegrzynski>For opening this year, I have an interesting episode.

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<v Wojciech Wegrzynski>I was recently asked to create some more introductory level content in the podcast.

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<v Wojciech Wegrzynski>To, to help those, to transition into the fire safety engineering.

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<v Wojciech Wegrzynski>But.

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<v Wojciech Wegrzynski>Also to help all other fire engineers.

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<v Wojciech Wegrzynski>Around a level, their knowledge base.

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<v Wojciech Wegrzynski>And, I did record such an episode.

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<v Wojciech Wegrzynski>I say, I would consider myself.

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<v Wojciech Wegrzynski>Fairly advanced fire user.

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<v Wojciech Wegrzynski>Uh, however, I still thoroughly enjoy talking about basics.

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<v Wojciech Wegrzynski>So I am completely sure everyone can enjoy this type of content.

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<v Wojciech Wegrzynski>I like mini series.

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<v Wojciech Wegrzynski>I may actually frame this into some sort of introduction to the fire mini series and I hope in this form, it will be easier to find it and benefit.

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<v Wojciech Wegrzynski>From it.

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<v Wojciech Wegrzynski>And my first guest is Dr.

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<v Wojciech Wegrzynski>Rory Hadden or University of Edinburgh.

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<v Wojciech Wegrzynski>Rory's a very, well-known a world-class Firestar, he's an expert in combustion expert in one wildfire dynamics.

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<v Wojciech Wegrzynski>He's an investigator.

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<v Wojciech Wegrzynski>He is very all around Mr.

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<v Wojciech Wegrzynski>Fire engineer.

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<v Wojciech Wegrzynski>So I'm was very happy that he took my invite, especially that he's a very good academic and.

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<v Wojciech Wegrzynski>He students absolutely love him.

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<v Wojciech Wegrzynski>So he's also very well fit to talk about the basics and yeah, we wanted to talk about combustion and flames and stuff.

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<v Wojciech Wegrzynski>That's related to the chemistry of combustion.

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<v Wojciech Wegrzynski>Rory's chemist actually.

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<v Wojciech Wegrzynski>So, uh, that's the subject we've started with we've ended up, uh, we've ended up in very different places about.

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<v Wojciech Wegrzynski>Uh, they're all connected to fire and fire engineering.

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<v Wojciech Wegrzynski>So, yeah, I think that's it, it doesn't need them any more introduction.

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<v Wojciech Wegrzynski>Let's just spin the intro and jump into the episode.

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<v Wojciech Wegrzynski>Hello everybody.

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<v Wojciech Wegrzynski>Welcome to the Fire Science Show.

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<v Wojciech Wegrzynski>I'm here today with Dr.

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<v Wojciech Wegrzynski>Rory Hadden from University of Edinburgh.

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<v Wojciech Wegrzynski>Hey Rory.

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<v Wojciech Wegrzynski>Good.

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<v Wojciech Wegrzynski>Thank you.

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<v Wojciech Wegrzynski>And we're gonna talk about some, fundamental stuff in the fire science, uh, discipline.

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<v Wojciech Wegrzynski>I've been asking a recent survey to prepare more, introductory material for ones who entered the discipline from various ends of the world of science and engineering.

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<v Wojciech Wegrzynski>And as we all know, nobody becomes a fire engineer, by their will, but they come here as an accident.

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<v Wojciech Wegrzynski>Rory, what's, what's your story, how you became a fire engineer?

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<v Rory Hadden>a long story.

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<v Rory Hadden>mean, I guess it, I trace it back to, um, when I was in high school and we had to decide what career we wanted to have.

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<v Rory Hadden>and I told my chemistry teacher that I was going to do the special effects on James Bond movies.

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<v Wojciech Wegrzynski>was

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<v Rory Hadden>and Nice.

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<v Rory Hadden>was shot down as not really a viable career.

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<v Wojciech Wegrzynski>Um

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<v Rory Hadden>then I, uh, applied to be a chemical engineer and studied that at university because, I came from Aberdeen and we had lots of oil in those days, so that seems like a very sensible thing to do.

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<v Rory Hadden>then as I was finishing that degree, I took a class, in Fire Dynamics with Dougal Drysdale, which was great.

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<v Wojciech Wegrzynski>Okay.

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<v Rory Hadden>loved that.

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<v Rory Hadden>but by this point had kind of thought, well, there's no way that's going to be, a, a viable career for a chemical engineer like me.

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<v Rory Hadden>and then a few weeks later I got email from Guillermo who I think is known, uh, to this community, saying Hmm.

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<v Rory Hadden>are PhD positions available and if we were interested in doing a PhD in fire science, then we should go and talk to him.

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<v Rory Hadden>so I did.

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<v Rory Hadden>And then the rest is history, I guess from that point.

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<v Wojciech Wegrzynski>yeah.

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<v Wojciech Wegrzynski>Nice.

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<v Wojciech Wegrzynski>Another one in the club of, switching, professions and, and coming to fire science.

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<v Wojciech Wegrzynski>So even better, uh, put yourself in a mindset like what you would love to be told when you switched from chemical engineering into, into fire safety engineering or, or let's just, read out loud Drysdales quick because that's, that's probably a viable introduction to the discipline as.

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<v Wojciech Wegrzynski>most people, I think.

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<v Wojciech Wegrzynski>Yeah.

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<v Rory Hadden>most people I think Yeah

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<v Wojciech Wegrzynski>Actually in the end of this episode, the, in the shortness of the episode, I'm gonna try to list some reading, , resources because there are some really great introductory resources and, not everyone is aware of that.

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<v Wojciech Wegrzynski>And, it certainly helps.

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<v Wojciech Wegrzynski>So today I would, I would love to cover the aspects of flames and combustion and, and like the fires.

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<v Wojciech Wegrzynski>How, we define some things related to that.

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<v Wojciech Wegrzynski>what are the, the, definitions of, things that we meet every day.

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<v Wojciech Wegrzynski>And I, I would start maybe not that easy one, but, but the flame, like what exactly is the flame?

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<v Wojciech Wegrzynski>Like how, how do you define it as a fire engineer and how, how you define it as a chemist.

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<v Rory Hadden>I mean for me uh, this is a very interesting question and it's one that I ask at the start of my, second year, class, defining what a flame is.

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<v Rory Hadden>Everyone I think is familiar with it, right?

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<v Rory Hadden>You see it, it's this kind of, maybe it's yellow, maybe it's a little bit blue.

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<v Rory Hadden>when you start looking at actually what's going on there and you start exploring, the structure of the flame and why it looks like it looks, it becomes quite obvious, I think, what a flame is.

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<v Rory Hadden>It's really Hmm.

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<v Rory Hadden>than a volume in space where you have some kind of chemical reaction occurring.

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<v Rory Hadden>and what you

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<v Wojciech Wegrzynski>Hmm.

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<v Rory Hadden>as, as the flame, is maybe separate from the chemical processes that are going on.

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<v Rory Hadden>So I think it's useful to separate those two things.

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<v Rory Hadden>so Okay.

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<v Rory Hadden>reaction is simply the reaction between the fuel, uh, that is generated somehow from either a, it could be a gas directly, it could be, a liquid that you have to vaporize.

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<v Rory Hadden>It could be a solid that you have to pyrolize and maybe we'll talk about some of those words, uh, later on.

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<v Rory Hadden>But basically you have to get the fuel, uh, into a gas phase.

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<v Rory Hadden>then it mixes with air from the ambient environment that's surrounding the fuel, um, when those fuel and air are in the correct proport.

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<v Rory Hadden>The chemical reaction can occur if you have an ignition source nearby.

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<v Rory Hadden>Um, and that ignition source could of course be a spark or another small flame.

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<v Rory Hadden>the chemical reaction then proceeds, um, and as it proceeds, it generates energy.

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<v Rory Hadden>and that energy heats up that volume of, of material, the air and the fuel.

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<v Wojciech Wegrzynski>and

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<v Rory Hadden>as the, the fuel heats up, the chemical reaction goes faster.

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<v Rory Hadden>Um, and we end up generating quite a lot of energy.

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<v Rory Hadden>And what we see, uh, as the flame is Hmm.

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<v Rory Hadden>manifestation of all the energy that's generated.

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<v Rory Hadden>The yellow stuff are little soot particles, so tiny little balls of carbon, uh, that are heated up to the point where they.

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<v Rory Hadden>and that's what we see as a yellow part of the flame, the blue part.

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<v Rory Hadden>If you've got a flame that's blue, Hmm.

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<v Rory Hadden>seeing there is actually the molecules themselves of the fuel being heated up to the point where they begin to, not so much glow, but release blue light.

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<v Rory Hadden>Uh, I guess, so process is simply, it's a volume in space for a chemical reactions occurring.

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<v Rory Hadden>And what we see as the flame is kind of the manifestation of the energy that's released by that

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<v Wojciech Wegrzynski>reaction.

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<v Wojciech Wegrzynski>but, um, if you have a flame inside, it is, it's hollow like inside, there's fuel.

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<v Wojciech Wegrzynski>Outside of it is, is oxygen.

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<v Wojciech Wegrzynski>And they react fairly small space, right?

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<v Rory Hadden>an interesting point that I've I've been speaking about, I guess what we commonly would call a diffusion flame.

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<v Rory Hadden>the, the fire science world separates things into two categories, I guess, of diffusion flames and premixed flames.

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<v Rory Hadden>and that's a useful distinction to be able to make.

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<v Rory Hadden>And one, I guess most people will be

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<v Wojciech Wegrzynski>mm-hmm

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<v Rory Hadden>chemistry classes in school where you have the bunsen burner, and if you open that little hole at the bottom of the bunsen burner, you get the blue.

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<v Rory Hadden>And that's a premixed flame because the Mm-hmm air are mixed before they react.

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<v Rory Hadden>Um, if you close that hole at the bottom, you get a yellow flame, like you would from a match or whatever.

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<v Wojciech Wegrzynski>Okay

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<v Rory Hadden>flame.

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<v Rory Hadden>and it's called a diffusion flame because the process that controls the, the dynamics of that flame, the structure of that flame is the diffusion of air from the surroundings into that jet of fuel.

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<v Rory Hadden>and that diffusion process, really governs, I mean the, the shape of the flame, uh, govern also the temperature of the flame.

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<v Rory Hadden>and it's really quite, I think, a fundamental part of fire science to understand like, what is that diffusion process and how does that result in the types of flames that we see?

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<v Rory Hadden>In most fire scenarios, we don't have the convenience of a premixed flame.

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<v Rory Hadden>That's something that a combustion scientist might be lucky enough to be able to study.

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<v Rory Hadden>but that's not something that as fire scientists, we have the privilege of dealing with.

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<v Rory Hadden>We have to work with slightly more, I dunno, dunno, more complex.

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<v Rory Hadden>It's just different, isn't it?

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<v Rory Hadden>The different physics of a

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<v Wojciech Wegrzynski>diffusion flame.

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<v Wojciech Wegrzynski>I guess the flow patterns play a significant role in how these flames unravel and behave and, like it.

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<v Wojciech Wegrzynski>You have fuel generated from something, you have oxygen that technically is everywhere around, but in reality, it's not.

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<v Wojciech Wegrzynski>The, the fuel burns the, the oxygen around.

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<v Wojciech Wegrzynski>So it needs to be replaced and replaced and replaced Conveniently.

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<v Wojciech Wegrzynski>It, it generates, uh, hot temperature gas, which has lower density than surrounding air, which creates a movement of its own.

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<v Wojciech Wegrzynski>It's like, I dunno.

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<v Wojciech Wegrzynski>Did you ever define a fire as a  we, we thought about like, it's, it's a nice, um, concept to show fire as a pump.

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<v Wojciech Wegrzynski>It sucks the air, it burns the, the fuel and releases gases and, and it's like a system like in an engine

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<v Rory Hadden>the, the kind of fire is a pump, uh, analogy works pretty well in, for example, a compartment fire analysis where you have, um pretty well defined flows, of air entering a space, and then the hot smoke and gases leaving, uh, leaving the compartment.

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<v Rory Hadden>All of that is driven by, yeah, the size of the fire.

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<v Rory Hadden>And, sorry, the average temperature in that compartment.

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<v Rory Hadden>And I think that that's quite an interesting point well when it comes to looking at, at flames.

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<v Rory Hadden>Cause one of the questions that, you know, we often get asked is, is the temperature of a fire?

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<v Rory Hadden>And that's a very tricky

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<v Wojciech Wegrzynski>Oh yeah

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<v Rory Hadden>to answer.

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<v Rory Hadden>one of the nice things about a diffusion flame is because the diffusion.

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<v Rory Hadden>It's controlled by the, literally, by the diffusion of oxygen into the fuel.

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<v Rory Hadden>the range of temperatures that you get from a diffusion flame doesn't really depend on what's burning.

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<v Rory Hadden>It really only depends on this diffusion, concept.

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<v Rory Hadden>and therefore the flame temperature, I don't know, more or less 1200 Celsius, maybe 1500, something like that.

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<v Rory Hadden>It's not going to vary,

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<v Wojciech Wegrzynski>too.

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<v Rory Hadden>Um, but that is not, but when you start talking about the temperature of the fire, well what do you mean by that?

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<v Rory Hadden>If you have, you know, if you're burning something in a Yeah maybe you mean the average temperature of the room, or do you mean the temperature of the flame?

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<v Rory Hadden>and that's one of the things I think a lot

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<v rory>of,

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<v Rory Hadden>people who come into the field are get a little bit, confused by or, I dunno, that sounds a bit harsh perhaps, but, you know, it's one of these ideas that's a little bit tricky, I think, to wrap your head around.

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<v Rory Hadden>And we see it quite often, you know, being expressed in kind of a colloquial term, oh, that was a very hot fire, or that was a very cool fire

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<v Wojciech Wegrzynski>Yeah

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<v Rory Hadden>think that that goes back to this whole concept of what is a fire, what is a flame?

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<v Rory Hadden>And it's about the physical manifestation of the combustion process.

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<v Rory Hadden>So

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<v Wojciech Wegrzynski>Mm

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<v Rory Hadden>is a very subjective thing.

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<v Rory Hadden>And as scientists and you know, as mm I think it's really important for us To talk in, you know, quantitative terms, not, not subjective, uh, terms.

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<v Rory Hadden>So the fire might feel really hot, but that doesn't mean that if you measure the temperature of that flame, it's any hotter than another fire.

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<v Rory Hadden>There's something else is usually

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<v Wojciech Wegrzynski>on I think that's, uh, a moment in, um, development of a fire safety engineer when they go through one of the earliest and biggest like, paradigm shifts in their perception of what they're touching.

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<v Wojciech Wegrzynski>Like, a flame is a flame and, and, it's separate from, from the fire.

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<v Wojciech Wegrzynski>And, and, and the fact that you have a, a flame inside your building, it doesn't mean it, it's gonna destroy the ceiling.

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<v Wojciech Wegrzynski>Like a candle flame is pretty hot, and if you put it against the ceiling, it's uh, not gonna do a much of impression on the ceiling.

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<v Wojciech Wegrzynski>But, if you have a thousand candles, there's a different story and Right

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<v Rory Hadden>of I mean the difference between temperature and heat, right?

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<v Rory Hadden>Is kind of what you're, what you're getting at there.

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<v Rory Hadden>Yeah of just because something's hot doesn't mean it's going to necessarily impart a lot of energy, onto something else.

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<v Rory Hadden>and I think Hmm that is probably one of the things that, certainly I remember learning, you know, through the study of heat transfer and whatever, that that's a pretty important, thing to wrap your head around and this, this, that the idea of temperature and heat flux are completely, separate,

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<v Wojciech Wegrzynski>concepts.

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<v Wojciech Wegrzynski>I would like to go, uh, further into the chemistry of flames.

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<v Wojciech Wegrzynski>So if you release, gas into environment, it's, it's not gonna always, like burn because there must be a certain like, uh, ratio of the fuel to the oxidizer in your environment.

00:12:19.253 --> 00:12:25.222
<v Wojciech Wegrzynski>So, let's talk about how we define them and how important they are for the fire engineering problems.

00:12:25.263 --> 00:12:32.620
<v Rory Hadden>I guess when we are defining the, I guess, the hazard posed by, a, a fuel, we usually would define that in terms of the flammability limits.

00:12:32.710 --> 00:12:37.017
<v Rory Hadden>So, as you've mentioned, you, Hmm to, not any mixture of air and fuel will burn.

00:12:37.017 --> 00:12:41.312
<v Rory Hadden>You have to get them in the, the right proportions in order, to basically sustain the chemistry.

00:12:41.312 --> 00:12:51.174
<v Rory Hadden>You know, if you've got, too much fuel and not enough oxygen while your, your reaction isn't going to work, and, and vice versa, if you have, too much oxygen, not enough fuel, you're not going to be able to generate enough energy.

00:12:51.376 --> 00:12:59.732
<v Rory Hadden>So this idea of, of the flammability limits is, is pretty well established and, you know, for more or less any fuel, uh, nowadays you can loop these up.

00:12:59.873 --> 00:13:10.913
<v Rory Hadden>The thing that I think is usually quite surprising to people, Is that the flammability ranges for most hydrocarbon fuels are the most common things that burn, are usually quite low.

00:13:10.913 --> 00:13:17.273
<v Rory Hadden>You know, you're usually, uh, in the region of Hmm a few percent, you know, two, 3% as the lower flammability limit.

00:13:17.283 --> 00:13:20.336
<v Rory Hadden>So you don't need very much fuel, in your air for it to burn.

00:13:20.557 --> 00:13:29.456
<v Rory Hadden>But once you get above, I don't know, maybe six or 7%, then for a lot of fuels it will be too, what we would say too, fuel rich in order to burn.

00:13:29.456 --> 00:13:31.856
<v Rory Hadden>There's too much fuel to sustain the reaction.

00:13:32.163 --> 00:13:35.840
<v Rory Hadden>of course of our exceptions, the flammability limits of hydrogen are, are massive.

00:13:35.899 --> 00:13:39.639
<v Rory Hadden>Now, off the top of my head, I don't remember, five to 75% something like this.

00:13:39.849 --> 00:13:41.332
<v Rory Hadden>methane is from

00:13:41.418 --> 00:13:42.207
<v Wojciech Wegrzynski>It must have been.

00:13:42.207 --> 00:13:42.408
<v Wojciech Wegrzynski>Yeah

00:13:43.363 --> 00:13:45.253
<v Rory Hadden>of methane in air, will burn.

00:13:45.442 --> 00:13:55.537
<v Rory Hadden>but Yeah into perhaps more common fuels, you know, your, your liquid hydrocarbons, and those sorts of things, you're down in this range of the lower flammability limit being around.

00:13:56.292 --> 00:14:01.511
<v Rory Hadden>You know, two or 3%, and then the upper flammability limit being around seven or 8%.

00:14:02.392 --> 00:14:03.871
<v Rory Hadden>it's always in, in these sorts of ballparks.

00:14:03.871 --> 00:14:14.158
<v Rory Hadden>And that's a really useful thing, to know for identifying, the hazards posed by mixtures of fuel and air, um, and how can look at whether or not, you know, it's possible to generate flammable mixtures.

00:14:14.177 --> 00:14:28.745
<v Rory Hadden>because from that concept, the concept of the flammability limits of fuel gas in air, uh, you can define the hazard posed by liquid fuels through the flashpoint, and the hazard posed by solid fuels through the, critical heat flux or the, the surface temperature and ignition.

00:14:28.945 --> 00:14:32.625
<v Rory Hadden>So all of those ignition phenomena are linked back to this idea of

00:14:33.004 --> 00:14:33.485
<v Wojciech Wegrzynski>limits.

00:14:33.724 --> 00:14:42.500
<v Wojciech Wegrzynski>I, I acetylene may have the, the, the widest, I think it has some crazy why, like 2% to 80 as well, like similar to, to hydrogens.

00:14:42.500 --> 00:14:45.139
<v Wojciech Wegrzynski>But this are not your common fuels.

00:14:45.139 --> 00:14:47.379
<v Wojciech Wegrzynski>Like, like you've said, many of them would have very narrow.

00:14:47.789 --> 00:14:57.582
<v Wojciech Wegrzynski>So when there's not enough oxygen, does it mean that that oxidation reaction is not happening or it just, uh, happens, but at the not, quick enough rate to to sustain it?

00:14:57.898 --> 00:15:00.868
<v Rory Hadden>both, I guess, Um, at some point it stops happening.

00:15:01.143 --> 00:15:07.067
<v Rory Hadden>Okay if you, can encourage chemical reactions to happen more by heating them up, or by increasing the pressure.

00:15:07.067 --> 00:15:08.975
<v Rory Hadden>So Hmm um, if you think of a chemical

00:15:09.190 --> 00:15:09.799
<v Wojciech Wegrzynski>Ah-huh

00:15:10.174 --> 00:15:15.934
<v Rory Hadden>when two molecules kind of bash into each other or collide, then you can increase Hmm of that happening.

00:15:15.985 --> 00:15:21.898
<v Rory Hadden>If you the temperature of your mixture so the fuel and air molecules are moving more

00:15:21.993 --> 00:15:22.153
<v Wojciech Wegrzynski>hmm

00:15:22.418 --> 00:15:23.587
<v Rory Hadden>or you can increase the pressure.

00:15:23.587 --> 00:15:25.347
<v Rory Hadden>So you're just forcing them to be closer together.

00:15:25.347 --> 00:15:29.623
<v Rory Hadden>And both of those things, effectively increase the probability of collisions.

00:15:29.993 --> 00:15:47.062
<v Rory Hadden>So the flammability limits we've just, we've just spoken about are all at, know, standard conditions at pressure, 20 hmm Celsius If you increase the pressure or you increase the temperature, then the flammability ranges typically widen, um, and you'll be able to Okay reactions to, to propagate.

00:15:47.205 --> 00:15:47.965
<v Wojciech Wegrzynski>Makes sense.

00:15:47.965 --> 00:15:56.205
<v Wojciech Wegrzynski>Yeah, and I guess also in oxygen reach, like I had an episode by about spacecraft where they would have an increased oxygen concentration.

00:15:56.205 --> 00:15:58.365
<v Wojciech Wegrzynski>You would have a a different limit again

00:15:58.519 --> 00:16:00.960
<v Rory Hadden>flammability limit you always have to check, you know, is it in air?

00:16:00.960 --> 00:16:04.679
<v Rory Hadden>Is it in oxygen, is it by volume percent, mass percent?

00:16:04.679 --> 00:16:06.440
<v Rory Hadden>So there's, there's a few details in there.

00:16:06.734 --> 00:16:12.086
<v Rory Hadden>but in principle, I mean, one of the things we are quite lucky about in fire science is most of our applications.

00:16:12.809 --> 00:16:17.039
<v Rory Hadden>Atmospheric pressure and, know, 21% oxygen in air

00:16:17.475 --> 00:16:17.965
<v Wojciech Wegrzynski>Yeah

00:16:18.120 --> 00:16:24.799
<v Rory Hadden>yet that's true stuff, high oxygen concentrations and high pressures to the, the clever people who do microgravity combustion.

00:16:25.284 --> 00:16:31.554
<v Wojciech Wegrzynski>Un unless you're doing fire safety engineering in Denver then, or Mexico City, then. It's, it's more tricky.

00:16:32.761 --> 00:16:33.539
<v Wojciech Wegrzynski>Uh, okay.

00:16:33.727 --> 00:16:43.134
<v Wojciech Wegrzynski>now on next on my list, we've discussed, the, the stoichometry of the, of the reaction, like how concentrations of, fuel and oxygen, allows the, the combustion to happen.

00:16:43.195 --> 00:16:45.495
<v Wojciech Wegrzynski>Now, I, I'm wondering about the ignitions.

00:16:45.495 --> 00:16:52.174
<v Wojciech Wegrzynski>You've said, uh, that there's a spark or there's a, a pilot flame that can ignite the, the mixture.

00:16:52.404 --> 00:16:55.361
<v Wojciech Wegrzynski>Like, what are the ways, how the mixture can be ignited?

00:16:55.361 --> 00:16:57.042
<v Wojciech Wegrzynski>I think that that's an interesting concept

00:16:57.322 --> 00:17:03.351
<v Rory Hadden>course if you have, even a flammable mixture of fuel and air within a, a volume, within a room, whatever.

00:17:03.779 --> 00:17:06.910
<v Rory Hadden>that will not necessarily immediately ignite, right?

00:17:06.910 --> 00:17:09.190
<v Rory Hadden>You have to put an ignition source there.

00:17:09.272 --> 00:17:14.032
<v Rory Hadden>the ignition source, for mixtures, I mean, can be, I mean, many things.

00:17:14.032 --> 00:17:15.032
<v Rory Hadden>You could have a small flame.

00:17:15.403 --> 00:17:20.843
<v Rory Hadden>Um, and a decent rule of thumb Hmm that, any flame will be capable of igniting a flammable mixture.

00:17:21.162 --> 00:17:22.339
<v Rory Hadden>you can use a spark.

00:17:22.355 --> 00:17:24.019
<v Rory Hadden>Okay are a little more complicated.

00:17:24.166 --> 00:17:32.512
<v Rory Hadden>usually there's a concept known as the minimum ignition energy, which is basically the energy spark has to contain, in order for it to ignite the mixture.

00:17:32.772 --> 00:17:34.432
<v Rory Hadden>You could just heat the mixture up.

00:17:34.603 --> 00:17:43.353
<v Rory Hadden>Um, so quite a lot of combustion, uh, work is done simply by putting a flammable mixture in a vessel and increasing the temperature of that vessel until you get ignition.

00:17:43.707 --> 00:17:47.787
<v Rory Hadden>Other things that can cause Hmm would be, you know, hot particles, hot surfaces.

00:17:48.037 --> 00:17:56.987
<v Rory Hadden>Um, and these are often, you know, if you are looking at fire hazards and processed plants or, or whatever, those are very often the kinds of hazards that you're most, I guess alert to.

00:17:57.299 --> 00:17:59.769
<v Rory Hadden>so ignition sources are very plentiful.

00:17:59.769 --> 00:18:07.363
<v Rory Hadden>And I think one of the nice things that, fire engineering has done and process safety does, is we kind of assume that there will always be one, right?

00:18:07.373 --> 00:18:08.039
<v Rory Hadden>So, we

00:18:08.220 --> 00:18:09.025
<v Wojciech Wegrzynski>of Mm-hmm

00:18:09.119 --> 00:18:12.718
<v Rory Hadden>have the conditions where there's a, a flammable mixer, we will get ignition.

00:18:12.817 --> 00:18:16.247
<v Rory Hadden>uh, and that's, I think that's pretty fundamental to how we study a lot of these problems.

00:18:16.817 --> 00:18:24.028
<v Rory Hadden>so, when you, when it comes to other modes of ignition, I guess, what we trying to do is try and divide them into, two categories.

00:18:24.357 --> 00:18:31.907
<v Rory Hadden>Uh, we have the piloted ignition, um, so that's where we, you know, physically put something there to, to start the, the combustion reaction.

00:18:32.278 --> 00:18:35.515
<v Rory Hadden>Um, or we have so-called spontaneous or auto ignition.

00:18:35.515 --> 00:18:42.978
<v Rory Hadden>well, so the, the piloted cases are quite nice because we can very easily define the ignition process.

00:18:43.394 --> 00:18:56.122
<v Rory Hadden>we heat up a, liquid or, a solid fuel usually, uh, and we get to a certain condition where the, the pilot flame that's there, or this pilot spark that's there will ignite the flammable gases that are evolved.

00:18:56.311 --> 00:19:01.162
<v Rory Hadden>When we look at auto ignition, it's a little bit more complicated because we have to understand much more.

00:19:01.734 --> 00:19:05.436
<v Rory Hadden>the processes that are going on in the solid phase and also in the gas phase.

00:19:05.846 --> 00:19:12.717
<v Rory Hadden>So we have to understand how the gas molecules are absorbing energy, how they're heating up, what is the temperature of that gas mixture.

00:19:12.777 --> 00:19:15.997
<v Rory Hadden>And that's, it's kind of an ugly problem to try and solve.

00:19:16.196 --> 00:19:22.106
<v Rory Hadden>so fire science from more or less the beginning took that ugly problem and said, we're just not going

00:19:22.247 --> 00:19:23.701
<v Wojciech Wegrzynski>deal with how convenient

00:19:23.886 --> 00:19:25.586
<v Rory Hadden>and we're gonna focus in

00:19:26.727 --> 00:19:26.967
<v Wojciech Wegrzynski>world

00:19:26.987 --> 00:19:33.400
<v Rory Hadden>because then when we're dealing with liquids and with solids, we can more or less ignore everything that's happening in the gas phase.

00:19:33.490 --> 00:19:40.843
<v Rory Hadden>We only have to worry about what's happening in the condensed phase, in the solid or in the liquid and that's a very, very powerful thing to be able to do.

00:19:40.843 --> 00:19:41.055
<v Rory Hadden>Right.

00:19:41.196 --> 00:19:53.257
<v Rory Hadden>but it does, or hide some of the complexities around the ignition process, which is the ignition is a gas But when we talk about it in terms of, of defining the hazard, we talk about things that are related to the solid or to the liquid.

00:19:53.257 --> 00:19:55.257
<v Rory Hadden>You know, the flashpoint is a property of the liquid.

00:19:55.436 --> 00:19:57.696
<v Rory Hadden>The critical heat flux is a property of the solid.

00:19:58.067 --> 00:20:00.696
<v Rory Hadden>Um, and I think quite often we forget.

00:20:00.846 --> 00:20:02.936
<v Rory Hadden>I think that that's what we're talking about.

00:20:02.936 --> 00:20:18.656
<v Rory Hadden>You know, and, and that in the end, the ignition process Hmm nothing more than heating your solid or your gas to the point where the mixture above the surface of that solid or that liquid is at the flammable low flammability limit.

00:20:18.656 --> 00:20:22.336
<v Rory Hadden>And if you've got a spark or if you have a pilot flame, then that's all you're doing, right?

00:20:22.336 --> 00:20:27.576
<v Rory Hadden>The conceptual leap is always the same, which is the flammability limits are what define flaming ignition.

00:20:28.156 --> 00:20:33.282
<v Rory Hadden>And, the rest of it is some kind of way to try to express that hazard.

00:20:33.692 --> 00:20:39.875
<v Wojciech Wegrzynski>it's, it's super funny that you say that fire science is conveniently uh, taken out and focused on liquids and gases.

00:20:39.875 --> 00:20:49.785
<v Wojciech Wegrzynski>Where in the today's fire science, like what are the sexiest topics We have, uh, timber in civil engineering, of course, that's solid phase facades.

00:20:49.785 --> 00:20:53.944
<v Wojciech Wegrzynski>Well, welcome to solid face, but in awkward, uh, configuration again.

00:20:54.444 --> 00:20:54.882
<v Wojciech Wegrzynski>And, there.

00:20:54.882 --> 00:20:57.082
<v Wojciech Wegrzynski>There's no escape from, uh, solving this.

00:20:57.082 --> 00:20:59.478
<v Wojciech Wegrzynski>It's, well, there, the solutions exist, right?

00:20:59.478 --> 00:20:59.655
<v Wojciech Wegrzynski>And

00:21:00.065 --> 00:21:01.204
<v Rory Hadden>the solutions exist.

00:21:01.204 --> 00:21:16.026
<v Rory Hadden>I think the, the issue, with a lot of this stuff is we understand pretty well, I think for individual materials, We've known, I mean, even before timber, in the built environment became a sexy topic, we knew how wood burned reasonably well.

00:21:16.026 --> 00:21:24.006
<v Rory Hadden>There's still many questions Yep fully have resolved, but, you know, before, that kind of started, you know, there's a very nice chapter in the Introduction to fire dynamics.

00:21:24.006 --> 00:21:29.559
<v Rory Hadden>There's a nice section there on how wood burns, how it ignites, you know, everything was laid out, before.

00:21:29.559 --> 00:21:30.359
<v Rory Hadden>Cause wood is not

00:21:30.434 --> 00:21:30.785
<v Wojciech Wegrzynski>Mm,

00:21:31.400 --> 00:21:33.240
<v Rory Hadden>material We have to you know, bear that in mind.

00:21:33.404 --> 00:21:37.079
<v Rory Hadden>yep engineer timber does not burn differently from regular wood, right?

00:21:37.079 --> 00:21:39.049
<v Rory Hadden>I mean, the laws of physics are the laws of physics.

00:21:39.140 --> 00:21:54.336
<v Rory Hadden>So, what I think is, is interesting about it is that once you start trying to apply that knowledge in the engineering design, I think that's maybe the difference that has happened in the last, I don't know how many years it is now, 5, 6, 7, 8 years I've been around doing this stuff.

00:21:54.873 --> 00:22:17.955
<v Rory Hadden>it becomes quite difficult to apply that knowledge and, and if you don't really understand where it all comes from and why piloted ignition theory exists in the way that it does, can see that it becomes a relatively complex, thing to try and understand, but the burning of all of these solid phase materials, as you say, whether it's facades, whether it's timber, or whether it's just, you know, the stuff that surrounds us, uh, in day-to-day life, you know, the compartment fires are governed by solid fuels.

00:22:17.955 --> 00:22:18.955
<v Rory Hadden>I mean, that's how it goes.

00:22:19.326 --> 00:22:23.875
<v Rory Hadden>Um, we need to, we need to understand that process of ignition, of solids.

00:22:23.875 --> 00:22:29.246
<v Rory Hadden>And I think, unfortunately for fire engineers, we're, we're able to remove some complexity from our lives.

00:22:29.246 --> 00:22:42.873
<v Rory Hadden>But the burning of solids is probably amongst the most complex problems that, science and engineering can, can try and solve just because there are so many very strongly coupled phenomena, um, which is why I love doing it right, is why I

00:22:42.972 --> 00:22:43.653
<v Wojciech Wegrzynski>it really interesting.

00:22:43.732 --> 00:22:44.222
<v Wojciech Wegrzynski>Yeah.

00:22:44.522 --> 00:22:45.163
<v Wojciech Wegrzynski>tell me more.

00:22:45.542 --> 00:22:54.173
<v Wojciech Wegrzynski>if, if you can just list like how this phenomenal couple, I think it's, it's fascinating to understand how much complexity there is in a burning log of timber

00:22:55.932 --> 00:22:57.133
<v Rory Hadden>of timber is a pretty good example.

00:22:57.133 --> 00:23:00.133
<v Rory Hadden>I mean, if you think about just the processes that are going on, right?

00:23:00.133 --> 00:23:01.653
<v Rory Hadden>We've got to heat the thing up.

00:23:01.653 --> 00:23:08.952
<v Rory Hadden>So we've got heat transfer processes, conduction, radiation, all playing a role, uh, in the burning of a piece of, of timber.

00:23:09.410 --> 00:23:10.736
<v Rory Hadden>we've then got the chemical reactions.

00:23:10.736 --> 00:23:12.096
<v Rory Hadden>We've got the pyrolysis process.

00:23:12.496 --> 00:23:17.415
<v Rory Hadden>Pyrolysis is the decomposition the solid fuel into flammable gases.

00:23:17.665 --> 00:23:21.529
<v Rory Hadden>Uh, and in the case of a piece of timber also leaves behind, a solid char.

00:23:21.529 --> 00:23:21.930
<v Rory Hadden>Okay?

00:23:21.930 --> 00:23:26.655
<v Rory Hadden>So we've got, Mm-hmm reaction that is, turning a solid material into gases.

00:23:27.135 --> 00:23:30.935
<v Rory Hadden>Maybe you can also get some tar there as well, so into some liquids.

00:23:31.185 --> 00:23:33.615
<v Rory Hadden>Um, and then we still have this solid char left behind.

00:23:33.615 --> 00:23:35.215
<v Rory Hadden>So we've got all three phases,

00:23:35.228 --> 00:23:35.556
<v rory>of

00:23:35.556 --> 00:23:35.796
<v Rory Hadden>matter.

00:23:36.057 --> 00:23:36.640
<v Wojciech Wegrzynski>Mm-hmm

00:23:36.710 --> 00:23:40.093
<v Rory Hadden>got chemical reactions that are occurring, on very complex molecules.

00:23:40.093 --> 00:23:41.532
<v Rory Hadden>You know, the, the composition of wood is.

00:23:41.952 --> 00:23:48.282
<v Rory Hadden>It's reasonably well known, but the, the decomposition of that, of those molecules is not so easy to figure out.

00:23:48.282 --> 00:23:49.603
<v Rory Hadden>That will be temperature dependent.

00:23:49.736 --> 00:23:57.816
<v Rory Hadden>and it'll also depend probably on the oxygen concentration, which brings us to the next part, which is we've got to get oxygen from the environment to the fuel.

00:23:57.986 --> 00:24:07.769
<v Rory Hadden>Um, so we've got a mass transfer problem, um, and we've also got the fluid mechanics because we have hot gases rising up, and that's creating, a whole sort of buoyantly driven airflows.

00:24:08.099 --> 00:24:12.569
<v Rory Hadden>So I mean, we've got heat transfer, fluid mechanics, chemical reactions, mass transfer.

00:24:12.700 --> 00:24:18.086
<v Rory Hadden>Uh, we've got the whole suite of things that are complex to solve the complex to solve.

00:24:18.296 --> 00:24:21.470
<v Rory Hadden>because very often we don't know is actually what it is, right?

00:24:21.470 --> 00:24:30.470
<v Rory Hadden>We've got all these intermediate stages, you know, what is the exact composition at this position beneath the surface at this time, and how does that change Hmm chemical processes?

00:24:31.765 --> 00:24:37.845
<v Rory Hadden>actually is the concentration of oxygen near the surface of the log, cuz that will change how the char oxidation occurs.

00:24:38.214 --> 00:24:45.565
<v Rory Hadden>So it's spatially difficult to resolve, temporarily difficult to resolve, and never really have enough information.

00:24:45.565 --> 00:24:48.221
<v Rory Hadden>And also, I don't know how you could even get some of that information.

00:24:48.221 --> 00:24:56.464
<v Rory Hadden>I mean, it's, I think that's one of the tricky things is, you know, the, you can't just stick a probe to measure everything because then you will change the whole system again.

00:24:56.595 --> 00:25:07.019
<v Rory Hadden>So me the, the ignition and the burning of, of solid fuels is, so complex and so fascinating that, I think it does a disservice very often to overly simplify it.

00:25:07.259 --> 00:25:16.569
<v Rory Hadden>Although, you know, there are, I think simplification is of course gonna be required if anybody wants to, to apply this in kind of a, an engineering context rather than just a study as a scientific context.

00:25:17.010 --> 00:25:19.175
<v Rory Hadden>so the question then becomes how do you simplify?

00:25:19.175 --> 00:25:24.455
<v Rory Hadden>And to do that, you have to know what are the most important steps there, you know, is the most important step.

00:25:24.455 --> 00:25:27.462
<v Rory Hadden>The heat transfer is the most important step of oxygen.

00:25:27.462 --> 00:25:38.480
<v Rory Hadden>Cause if you know what the most important steps are, you can design, a tool or a method to help you, simplify, I should say, the problem, uh, such that it can be applied, but you have to go into all of the details, I think

00:25:38.829 --> 00:25:39.190
<v Wojciech Wegrzynski>you can

00:25:39.200 --> 00:25:40.816
<v Rory Hadden>just, that, make that, uh,

00:25:41.046 --> 00:25:41.486
<v Wojciech Wegrzynski>simplification.

00:25:41.762 --> 00:25:44.982
<v Wojciech Wegrzynski>Man, this was supposed to be an introductory epi and it's already crazy.

00:25:45.333 --> 00:25:52.779
<v Wojciech Wegrzynski>I , I'm sorry to everyone who came here to, to figure out the, the definitions, but, that's the beauty of fire science.

00:25:52.779 --> 00:26:04.210
<v Wojciech Wegrzynski>Like that's the reason why it's such a complicated science and, why we are not getting out of our jobs anywhere soon because that's, it's, it's, yeah, it's not easy

00:26:04.289 --> 00:26:07.529
<v Rory Hadden>and and in some levels, you know, why should it be, right?

00:26:07.559 --> 00:26:08.849
<v Rory Hadden>I think very often,

00:26:09.059 --> 00:26:09.549
<v Wojciech Wegrzynski>Yeah

00:26:09.863 --> 00:26:14.339
<v Rory Hadden>people have a perception that, uh, I've seen fires, you know, I've built campfires.

00:26:14.339 --> 00:26:16.539
<v Rory Hadden>I, you know, have a wood burner at home.

00:26:16.569 --> 00:26:18.500
<v Rory Hadden>I have a, a coal firer at home.

00:26:18.648 --> 00:26:21.559
<v Rory Hadden>and, and there's this kind of everyday familiarity with fires.

00:26:21.559 --> 00:26:29.880
<v Rory Hadden>And one of the things I see, you know, as my job, um, when I'm teaching, you know, undergraduate students or MSC students, is to try and break down that, you know that.

00:26:30.182 --> 00:26:39.450
<v Rory Hadden>comfort with the phenomena of fire and trying to introduce all of these complexities because, I think I've said it before, but the, one of the best bits of engineering in my house is the fireplace.

00:26:39.450 --> 00:26:46.089
<v Rory Hadden>You know, it's extraordinarily simple, but every single time I light a fire there, I get a more or less consistent result.

00:26:46.089 --> 00:26:53.930
<v Rory Hadden>You know, the, from how the chimney operates Hmm air flows in, through the, the bottom of the fireplace to how the heat's radiated into the room.

00:26:54.119 --> 00:27:00.130
<v Rory Hadden>It's an extremely efficient piece of engineering and something that we engineered before we really understood all of these,

00:27:00.394 --> 00:27:00.815
<v Wojciech Wegrzynski>Hmm

00:27:01.363 --> 00:27:05.903
<v Rory Hadden>so think, the complexity and things, I think we have to acknowledge that they're there.

00:27:06.145 --> 00:27:07.455
<v Rory Hadden>as we go through um

00:27:07.685 --> 00:27:07.965
<v Wojciech Wegrzynski>these

00:27:07.976 --> 00:27:08.365
<v Rory Hadden>problems.

00:27:08.769 --> 00:27:19.855
<v Wojciech Wegrzynski>I think, uh, another breakthrough in in your personal pathway as a fire safety engineer comes when, for the first time you experience, a really large fire.

00:27:20.266 --> 00:27:35.393
<v Wojciech Wegrzynski>like when you take a piece of, I don't know, polyethylene, uh, and you put it into bomb to measure the heat of combustion, in the end you get a slightly hot water and, and a number.

00:27:35.692 --> 00:27:39.952
<v Wojciech Wegrzynski>You put that thing in a cone calorimeter okay, it's gonna burn quite nicely.

00:27:39.952 --> 00:27:48.680
<v Wojciech Wegrzynski>But it's not a very, very impressive thing uh, if you take a larger piece of that and somehow ignite it, it's, it's interesting to observe how it ignites.

00:27:49.019 --> 00:27:53.972
<v Wojciech Wegrzynski>And if you put that thing on a facade, it's a raging inferno it's nothing you've seen in your life.

00:27:53.972 --> 00:28:01.150
<v Wojciech Wegrzynski>Like someone opened a portal to hell and, For me, it was a huge lesson of, I, I didn't even know, know the world.

00:28:01.150 --> 00:28:07.230
<v Wojciech Wegrzynski>Like it, it was really interesting to see how much the scale changes the fire.

00:28:07.730 --> 00:28:26.415
<v Wojciech Wegrzynski>And once you heat a particular large scale with a very bad material, how bad and how quickly it can, evolve, and once you first time in your life experience that, uh, when you see a results from cone color, okay, this one has like 20% more heat release rate than the previous one.

00:28:26.737 --> 00:28:29.619
<v Wojciech Wegrzynski>that doesn't seem like a, such a huge deal, but it is in the end.

00:28:29.859 --> 00:28:30.500
<v Wojciech Wegrzynski>It it is.

00:28:31.210 --> 00:28:33.140
<v Wojciech Wegrzynski>Same when you observe compartment fires.

00:28:33.140 --> 00:28:39.653
<v Wojciech Wegrzynski>So I I wondered why in larger scale, these bad fuels are even worse?

00:28:39.653 --> 00:28:39.932
<v Wojciech Wegrzynski>Why?

00:28:39.932 --> 00:28:52.210
<v Wojciech Wegrzynski>Why these fires can so tremendously accelerate and, uh, Why we have such a hard time slowing that down, like making these materials slow down are um

00:28:52.960 --> 00:29:01.259
<v Rory Hadden>are uh all about feedbacks  The thing that you often don't see in a small scale test, is really the, the way in which those feedbacks occur.

00:29:01.259 --> 00:29:05.940
<v Rory Hadden>And that's usually because a test has been designed in some way to try and eliminate those, right?

00:29:05.940 --> 00:29:08.460
<v Rory Hadden>Because they're difficult to control and whatever.

00:29:08.640 --> 00:29:20.363
<v Rory Hadden>But once you start building up, you know, big assemblies, um, and, and you let the fire, experience or certainly let the materials experience those feedbacks then you get really rapid or you can get really rapid fire growth.

00:29:20.363 --> 00:29:25.002
<v Rory Hadden>And I think that that is a thing that takes most people by surprise, certainly takes me by surprise.

00:29:25.053 --> 00:29:31.883
<v Rory Hadden>Um, now and then when you are doing a large scale test and you know, it's these, it's these transitions, uh, that the fire go through.

00:29:31.883 --> 00:29:34.890
<v Rory Hadden>The most famous one of course, would be the flashover in a compartment fire.

00:29:35.069 --> 00:29:43.650
<v Rory Hadden>But even just if you've got, you know, a spreading wildfire or a, a spread on a facade as the flames you know, they get larger, you're burning more fuel.

00:29:43.710 --> 00:29:47.730
<v Rory Hadden>You start to get things like the effects of char oxidation if you've got charring materials.

00:29:48.154 --> 00:29:51.154
<v Rory Hadden>Playing a role, uh, external variables, you know, the flow.

00:29:51.494 --> 00:29:55.127
<v Rory Hadden>All of these things, generally act to enhance the fire spread.

00:29:55.127 --> 00:29:56.928
<v Rory Hadden>And we don't often see that in a small scale

00:29:57.157 --> 00:29:57.877
<v Wojciech Wegrzynski>in a laboratory,

00:29:58.768 --> 00:30:06.107
<v Rory Hadden>because we don't have, you know, we're not releasing enough energy to create huge buoying flows, and we don't have the external influence of wind, for example.

00:30:06.397 --> 00:30:12.580
<v Rory Hadden>So I think for me, the, the way of, of measuring the size of a fire, is always one that's a bit tricky.

00:30:12.580 --> 00:30:15.340
<v Rory Hadden>And then I'm gonna try and pull this back onto a learning point if we can.

00:30:15.765 --> 00:30:23.075
<v Rory Hadden>uh, is, you know, when we measure the size of a fire, we don't do it based on how tall is the flame or how wide is the thing that's burning.

00:30:23.938 --> 00:30:26.688
<v Rory Hadden>we always measure it in terms of the energy that's released.

00:30:27.563 --> 00:30:33.326
<v Rory Hadden>And, you know we would call that the Hmm rate, or the energy release rate or, or what have you.

00:30:33.326 --> 00:30:40.923
<v Rory Hadden>But the rate at which basically the, the, the fire's producing energy, and that is measured in, it's a unit of power, right?

00:30:40.923 --> 00:30:43.883
<v Rory Hadden>So it's, um, measured in watts, maybe kilowatts,

00:30:45.032 --> 00:30:45.712
<v Wojciech Wegrzynski>megawatts

00:30:45.722 --> 00:30:47.242
<v Rory Hadden>uh, some some proper

00:30:47.673 --> 00:30:47.913
<v Wojciech Wegrzynski>going.

00:30:48.182 --> 00:30:53.742
<v Wojciech Wegrzynski>which is jewels per second, like the amount of energy generated per second of of the process Right

00:30:53.873 --> 00:31:01.810
<v Rory Hadden>per second,  you know, in a fire you can go from something, I don't know, a candle flame is on the order of, I don't know, 10 watts, something like that.

00:31:02.005 --> 00:31:07.647
<v Rory Hadden>but you can have very easily, a compartment fire that's on the order of megawatts in size.

00:31:07.788 --> 00:31:12.167
<v Rory Hadden>And if you look at some, uh, extreme wildfire behaviors, they will be measured.

00:31:12.438 --> 00:31:15.407
<v Rory Hadden>It's usually measured in terms of megawatts per meter, right.

00:31:15.407 --> 00:31:18.230
<v Rory Hadden>And that's meter of the, the width of the fire line So

00:31:18.724 --> 00:31:22.954
<v Wojciech Wegrzynski>uh, I, I just had Kevin McGrain on the show when we were discussing World Trade Center.

00:31:22.994 --> 00:31:34.421
<v Wojciech Wegrzynski>Listeners know that you don't know that , but, uh, listeners know that there was a Kevin on, on the show and, from their assessment, uh, size of the fire in the World Trade Center was approximately 2000 megawatt.

00:31:34.421 --> 00:31:35.980
<v Wojciech Wegrzynski>So it was in the gigawatt range.

00:31:36.310 --> 00:31:38.500
<v Wojciech Wegrzynski>So, so that's that's impressive Yeah

00:31:38.645 --> 00:31:44.113
<v Rory Hadden>you start putting these numbers in context, I mean, it's, you try to find something to Yeah a two gigawatt fire.

00:31:44.113 --> 00:31:46.232
<v Rory Hadden>I don't know what, you know, what is that?

00:31:46.232 --> 00:31:48.192
<v Rory Hadden>Is that a nuclear power station?

00:31:48.192 --> 00:31:48.833
<v Rory Hadden>Is that the output?

00:31:48.833 --> 00:31:49.833
<v Rory Hadden>I mean, I, I don't even know.

00:31:49.833 --> 00:31:53.313
<v Rory Hadden>You start, it's getting handle on this and what it feels like is quite, is quite tricky.

00:31:53.313 --> 00:32:01.296
<v Rory Hadden>And I, I Hmm people who haven't, been able to do this is to, you know, try and find a lab somewhere that will let you come in and see what a fire looks like.

00:32:01.296 --> 00:32:07.240
<v Rory Hadden>Because, in our lab we can run fires of up to, around a megawatt, depending on who's looking maybe a little bit more.

00:32:07.569 --> 00:32:19.069
<v Rory Hadden>and you know, I think the first time somebody sees a fire that's of that size, it's eyeopening, you a one megawatt fire is Mm think many people would feel comfortable dealing with or being near

00:32:19.349 --> 00:32:19.700
<v Wojciech Wegrzynski>Mm

00:32:19.782 --> 00:32:24.173
<v Rory Hadden>uh, so getting, and it's difficult to put, you know, sizes on this, you know, waste paper, basket fire, what's that?

00:32:24.173 --> 00:32:25.133
<v Rory Hadden>A hundred kilowatts.

00:32:25.133 --> 00:32:26.373
<v Rory Hadden>I mean, maybe something in that.

00:32:26.843 --> 00:32:28.472
<v Rory Hadden>In that order, maybe a little bit less.

00:32:28.833 --> 00:32:38.663
<v Rory Hadden>so it's difficult to, I think for, because of the way of the units are, are given, you know, this, this idea of power, it's quite difficult for people to get a sense of that, think.

00:32:39.279 --> 00:32:43.772
<v Rory Hadden>but, you know, hmm relate it, you know, the, a kettle is, you know, three kilowatts.

00:32:43.772 --> 00:32:44.133
<v Rory Hadden>Right.

00:32:44.133 --> 00:32:45.292
<v Rory Hadden>But does that help?

00:32:45.292 --> 00:32:45.653
<v Rory Hadden>I don't

00:32:45.843 --> 00:32:46.403
<v Wojciech Wegrzynski>know Right.

00:32:46.403 --> 00:32:48.170
<v Wojciech Wegrzynski>You a hundred kettles per second.

00:32:48.170 --> 00:32:50.329
<v Wojciech Wegrzynski>That's not, not a great unit of measure Right

00:32:52.440 --> 00:32:57.960
<v Rory Hadden>of the things that is a bit tricky and until you, you see it, you know, the, it's quite a difficult measurement to get to wrap your head around.

00:32:58.150 --> 00:33:04.019
<v Rory Hadden>but the useful thing about measuring heat release rate, is you can use it to track the fire growth.

00:33:04.019 --> 00:33:05.579
<v Rory Hadden>So fires don't normally start

00:33:06.248 --> 00:33:06.647
<v Wojciech Wegrzynski>Hmm

00:33:07.012 --> 00:33:07.692
<v Rory Hadden>release rate, right?

00:33:07.972 --> 00:33:09.492
<v Rory Hadden>Normally fires grow in some way.

00:33:09.492 --> 00:33:11.212
<v Rory Hadden>They start small and they get.

00:33:12.143 --> 00:33:17.232
<v Rory Hadden>and the nice thing about heat release rate is you can track the fire growth, using this, this measurement.

00:33:17.546 --> 00:33:21.705
<v Rory Hadden>and we've got different ways we can measure heat release rate, which is I think, quite useful.

00:33:21.955 --> 00:33:36.205
<v Rory Hadden>Um, but uh, we can talk about them Hmm a minute, but nevertheless, tracking the fire size, um, as a function of time is really, really useful in terms of how we understand the burning of individual materials, but also how we understand the burning of objects.

00:33:37.086 --> 00:33:41.309
<v Rory Hadden>so it's one of these kind of concepts that unifies uh, a lot of things in fire science.

00:33:41.319 --> 00:33:51.425
<v Rory Hadden>So, if you're running a small scale test in the laboratory, for example, using the cone calorimeter, which is, a device that basically allows us to impose some heating onto a material.

00:33:52.385 --> 00:33:56.105
<v Rory Hadden>the heating is by radiation that increases the temperature of the material.

00:33:56.519 --> 00:34:05.182
<v Rory Hadden>eventually we will reach the point where we will have a flammable mixture, as the material decomposes into the Mm-hmm A flammable mixture will exist above the surface of the fuel.

00:34:05.313 --> 00:34:11.012
<v Rory Hadden>We have a pilot flame, sorry, pilot spark, in there that will ignite those Hmm and the material will burn.

00:34:11.202 --> 00:34:14.213
<v Rory Hadden>Once the material starts burning, we can measure the energy release.

00:34:14.213 --> 00:34:26.213
<v Rory Hadden>And if we have something like, a common plastic polyethylene was an example you used before, that will burn in a way that basically very quickly it reaches, uh, kind of a, a maximum steady value and it'll burn like that.

00:34:26.302 --> 00:34:30.782
<v Rory Hadden>Um, releasing more or less a constant amount of energy until we consume all of the material.

00:34:31.072 --> 00:34:35.702
<v Rory Hadden>Um, and then of course, there's no fuel left, nothing to burn, so the heat release rate drops back to zero.

00:34:36.730 --> 00:34:39.715
<v Rory Hadden>materials if you've charring materials, so things like, timber.

00:34:40.411 --> 00:34:45.490
<v Rory Hadden>Um, or any kind of, uh, cellulose kind of derived product, they're typically all charring.

00:34:45.820 --> 00:34:51.864
<v Rory Hadden>Um, that will, that means that the, once the sample is heated, we produce the flammable gases in exactly the same way as before.

00:34:52.114 --> 00:34:53.505
<v Rory Hadden>We then ignite those gases.

00:34:53.514 --> 00:34:56.498
<v Rory Hadden>and in this case we can track the energy release as we do before.

00:34:56.498 --> 00:35:05.137
<v Rory Hadden>And what we'll see is the energy release, uh, immediately reaches some kind of maximum value and then decreases as the material burns.

00:35:05.215 --> 00:35:09.840
<v Rory Hadden>and it never reaches really a steady it's always kind of decreasing as the material burns.

00:35:09.840 --> 00:35:19.324
<v Rory Hadden>And that's really useful information because now we've got information that, um, is telling us how much energy these materials are releasing and also how they're releasing, that energy.

00:35:19.664 --> 00:35:23.965
<v Rory Hadden>And the thing about heat release rate is, I mentioned before about feedbacks.

00:35:23.965 --> 00:35:30.391
<v Rory Hadden>It's one of the main things that The energy that you release from the fire will, determine how much energy you have available.

00:35:31.090 --> 00:35:39.315
<v Rory Hadden>To go back to the material to heat it up some more, to keep it burning, to spread the flame to grow the fire that way it will also determine the airflows that you get around.

00:35:39.315 --> 00:35:44.684
<v Rory Hadden>So if you have, a larger heat release rate, you'll generate more, uh, more buoyant airflow.

00:35:44.974 --> 00:35:50.525
<v Rory Hadden>Um, larger airflows typically will again, be a positive feedback, uh, into a, a fire system.

00:35:50.775 --> 00:35:59.927
<v Rory Hadden>So by tracking that evolution, by understanding how, different materials burn and how they release the energy as they burn, you can learn a lot about how things might uh

00:35:59.958 --> 00:36:05.422
<v Wojciech Wegrzynski>might manifest I, I have another observation, another change in the life of a fire safety engineer.

00:36:06.000 --> 00:36:21.949
<v Wojciech Wegrzynski>so the fact that something is difficult to ignite doesn't mean it doesn't ignite, and it doesn't mean it burns it, it just means that this particular setting of these feedbacks that you've described is slightly different than from material.

00:36:21.949 --> 00:36:23.389
<v Wojciech Wegrzynski>Let's, let's say an easy to ignite.

00:36:23.519 --> 00:36:27.023
<v Wojciech Wegrzynski>So if you have polyethylene, it's, let's say easy to ignite.

00:36:27.023 --> 00:36:29.023
<v Wojciech Wegrzynski>So you need lower heat feedback.

00:36:29.472 --> 00:36:36.103
<v Wojciech Wegrzynski>It can self sustain the combustions simpler, quicker, easier, and just, just burn off.

00:36:36.202 --> 00:36:40.175
<v Wojciech Wegrzynski>And if you have, let's say, strongly fire retarded polyethylene.

00:36:40.481 --> 00:36:43.521
<v Wojciech Wegrzynski>where someone has engineered modifications to this material.

00:36:43.971 --> 00:36:45.681
<v Wojciech Wegrzynski>So it is harder to ignite.

00:36:45.811 --> 00:36:51.340
<v Wojciech Wegrzynski>It doesn't mean it does not, it, it just means this whole, feedback loop is on, on a quite a different level.

00:36:51.681 --> 00:36:58.338
<v Wojciech Wegrzynski>But if you reach that level and you, you get net positive heat, loop in there.

00:36:58.588 --> 00:37:04.588
<v Wojciech Wegrzynski>So by by burning it, it, it generates more energy than it needs to ignored and keep burning.

00:37:04.588 --> 00:37:05.827
<v Wojciech Wegrzynski>So, so it's not positive.

00:37:06.268 --> 00:37:07.588
<v Wojciech Wegrzynski>It'll eventually grow.

00:37:07.588 --> 00:37:19.467
<v Wojciech Wegrzynski>And, and I, I think that's something that, that we observe in, in, in this faucet were brought as an, as an example that you can put a very good materials from our, for our standards, like very high euro class materials.

00:37:19.467 --> 00:37:23.394
<v Wojciech Wegrzynski>And because of this specific way how.

00:37:23.896 --> 00:37:25.186
<v Wojciech Wegrzynski>Facade is constructed.

00:37:25.186 --> 00:37:27.945
<v Wojciech Wegrzynski>That enables a lot of interesting feedback loops.

00:37:27.945 --> 00:37:28.346
<v Wojciech Wegrzynski>Inside.

00:37:28.806 --> 00:37:35.385
<v Wojciech Wegrzynski>You may still be in the regime where, okay, it's very hard to ignite, but after you do that, it can self sustain and, and propagate

00:37:35.965 --> 00:37:38.076
<v Rory Hadden>uh, people often ask what it is that I do.

00:37:38.215 --> 00:37:40.016
<v Rory Hadden>a fire scientist, you know, what the hell is that?

00:37:40.235 --> 00:37:49.496
<v Rory Hadden>And, you know, my, my response sometimes is a bit flippant, which is, you know, I, I take things that obviously burn and show that they don't, and I take things that shouldn't burn and show that they do.

00:37:49.693 --> 00:37:54.795
<v Rory Hadden>and you know, as long as something's got some carbon in it, I think, you know, we can usually find the way, to make it burn.

00:37:54.795 --> 00:37:56.195
<v Rory Hadden>And, and you're absolutely right.

00:37:56.195 --> 00:37:59.905
<v Rory Hadden>You know, this is the process of something burning, is all about these feedbacks.

00:37:59.905 --> 00:38:10.282
<v Rory Hadden>And actually the, the, is, you know, there's quite simple expressions, uh, for that, you know, I won't recite the equations now, but, you know, there's quite simple ways to conceptualize, that problem.

00:38:10.543 --> 00:38:14.797
<v Rory Hadden>And basically, Just because something is hard to ignite doesn't mean it won't burn.

00:38:14.797 --> 00:38:16.998
<v Rory Hadden>And I think those are concepts that often

00:38:17.382 --> 00:38:17.543
<v Wojciech Wegrzynski>Hmm

00:38:18.038 --> 00:38:19.797
<v Rory Hadden>sometimes a little bit misused.

00:38:19.797 --> 00:38:23.358
<v Rory Hadden>You know, something is fire retardant, well that means it will still burn.

00:38:23.358 --> 00:38:23.838
<v Rory Hadden>Right?

00:38:23.838 --> 00:38:27.757
<v Rory Hadden>You know, like it means it might be harder to ignite it, but it will still burn.

00:38:27.757 --> 00:38:49.257
<v Rory Hadden>And under some, you know, you also also have to ask the question like, what are the conditions that show that this is harder to ignite because, uh, you know, I can guarantee Hm know, a non-fire, retarded piece of wood and a fire retarded piece of wood in a compartment fire, the fire retardants aren't gonna be massively effective, uh, once you start having a heat flu of, you know, a hundred kilowatts per square meter.

00:38:49.268 --> 00:38:53.230
<v Rory Hadden>So, so you have to be a little bit careful about How you evaluate these things.

00:38:53.230 --> 00:38:57.630
<v Rory Hadden>But, but in the end, you know, the, the energy balance is what we're looking at.

00:38:57.650 --> 00:39:05.835
<v Rory Hadden>And if you're burning something, you have the heat feedback from the flame to the surface of the, the material that will keep it burning.

00:39:06.715 --> 00:39:08.115
<v Rory Hadden>and you will have some heat losses.

00:39:08.115 --> 00:39:11.063
<v Rory Hadden>And the heat losses can be, in many different forms.

00:39:11.670 --> 00:39:15.969
<v Rory Hadden>due to, surface reradiation, they can be due to conduction in depth.

00:39:16.159 --> 00:39:19.369
<v Rory Hadden>They can be due to, um, literally removing mats.

00:39:19.369 --> 00:39:25.489
<v Rory Hadden>You know, so if you're materials melting and dripping and flowing away, um, there's lots of ways to manipulate this, this energy balance.

00:39:25.489 --> 00:39:30.079
<v Rory Hadden>But in the end for something to burn, as you point out, you have to have more energy arriving at the.

00:39:30.565 --> 00:39:33.135
<v Rory Hadden>Then you need to pyrolize the next piece of

00:39:33.485 --> 00:39:33.684
<v Wojciech Wegrzynski>material

00:39:34.445 --> 00:39:48.260
<v Rory Hadden>I think this concept of fire retardants and, and whatever is, is one that, is, is quite complex to understand, in the end, because, you know, the, the chemical formulations can all sound a little bit tricky, but in the end, what you're basically doing is modifying that energy balance somehow.

00:39:48.260 --> 00:39:54.244
<v Rory Hadden>You could be doing it, by also, um, changing the properties of the flames so you can make the flame release less energy.

00:39:54.614 --> 00:40:00.161
<v Rory Hadden>Uh, you can also delay the formation of flail mixture by producing, inert gases.

00:40:00.161 --> 00:40:06.641
<v Rory Hadden>So things decomposed to form water or carbon Hmm All of those things, uh, can have an impact on the, the burning of the material.

00:40:06.820 --> 00:40:09.081
<v Rory Hadden>But it is at the end of the day a feedback.

00:40:09.181 --> 00:40:09.885
<v Rory Hadden>and if you can

00:40:09.945 --> 00:40:10.434
<v Wojciech Wegrzynski>Yeah

00:40:10.954 --> 00:40:14.525
<v Rory Hadden>energy in your system, then you can make, you can make something burn.

00:40:15.204 --> 00:40:15.405
<v Rory Hadden>yeah

00:40:15.657 --> 00:40:22.235
<v Wojciech Wegrzynski>and, um, to the fire safety engineer who's listening it's not that they don't work or, or they are useless.

00:40:22.244 --> 00:40:23.275
<v Wojciech Wegrzynski>It, it's not about that.

00:40:23.275 --> 00:40:29.034
<v Wojciech Wegrzynski>It's about understanding the purpose of these engineers changes to the materials.

00:40:29.244 --> 00:40:42.704
<v Wojciech Wegrzynski>If the purpose is to, make it harder to ignite by introducing these ways of, of additional heat losses and moving the, the balance away from the, the point you're changing the regime in which the fire can even start.

00:40:42.704 --> 00:40:47.295
<v Wojciech Wegrzynski>And I guess that was like a case of, ignition of a mattress by cigarette.

00:40:47.804 --> 00:41:00.039
<v Wojciech Wegrzynski>where, uh, Eventually engineered the material in a way that energy carried by this source is insufficient to ignite, which it's not a huge change from grand scheme of things.

00:41:00.210 --> 00:41:06.960
<v Wojciech Wegrzynski>Uh, perspective if there's a flashover in there that compartment, that sofa will burn as, as vigorously as as another one.

00:41:07.420 --> 00:41:14.360
<v Wojciech Wegrzynski>But you've changed the amount of fires that can happen because suddenly the common ignition source is enabled to, to cause a fire.

00:41:14.469 --> 00:41:17.880
<v Wojciech Wegrzynski>It's enabled to, to pass from just ignition to the fire Right

00:41:18.036 --> 00:41:20.074
<v Rory Hadden>that's exactly the role of a fire retardant.

00:41:20.074 --> 00:41:26.994
<v Rory Hadden>It's to make things harder to ignite and perhaps to, you know, then slow down those early stages of, of fire development.

00:41:27.005 --> 00:41:33.311
<v Rory Hadden>So, you know, you, you basically, you, you buy time, in order for people to evacuate and you know, all of these things to happen.

00:41:33.617 --> 00:41:41.130
<v Rory Hadden>and, and there are multiple ways of doing that and I think, you know, there are lots of statistics that show that that is successful, in terms of reducing the number of fires.

00:41:41.498 --> 00:41:45.661
<v Rory Hadden>but, the key thing I think to remember is that that's happening in the early stages of the fire.

00:41:45.661 --> 00:41:54.791
<v Rory Hadden>So if you're interested in that and you're looking at an Hmm calculation, for example, then I think, the fire retardant issue in material selection and material choice.

00:41:55.130 --> 00:42:07.590
<v Rory Hadden>But the question of does the fire retardant work at the scale of a compartment fire, of a sad fire, a wildfire, those are different And you know, you probably need different mitigation techniques, uh, to address that.

00:42:07.590 --> 00:42:09.518
<v Rory Hadden>There's no, no silver bullet in this.

00:42:09.518 --> 00:42:11.918
<v Rory Hadden>Uh, you know, there's not one, one Yeah

00:42:11.987 --> 00:42:19.936
<v Wojciech Wegrzynski>for everything I would also like to point out that cigarettes changed a lot and modern cigarettes carry much less energy as an ignition source.

00:42:20.335 --> 00:42:29.056
<v Wojciech Wegrzynski>Actually, from a lab fire laboratory perspective, that's quite a problematic, I think the last batch of cigarettes used for the test we had to purchase in Ukraine.

00:42:29.215 --> 00:42:34.456
<v Wojciech Wegrzynski>Cause the polish ones were, were not, uh, burning vigorous enough.

00:42:35.150 --> 00:42:38.460
<v Wojciech Wegrzynski>y you are also known, uh, as the, the wildfire scientist.

00:42:38.690 --> 00:42:42.900
<v Wojciech Wegrzynski>I wonder like we, we've talked about solid fuels like timber and stuff.

00:42:43.250 --> 00:42:47.672
<v Wojciech Wegrzynski>now loo looking at, living fuels, like, it, it, there's many, many differences.

00:42:48.190 --> 00:42:53.980
<v Wojciech Wegrzynski>one that for me is the most obvious is, is the, well two, two are obvious to me.

00:42:54.000 --> 00:42:57.179
<v Wojciech Wegrzynski>One is the moisture content in the fuel and the second is it's porosity.

00:42:57.630 --> 00:43:00.619
<v Wojciech Wegrzynski>So how does change this fundamental behavior?

00:43:00.730 --> 00:43:03.139
<v Wojciech Wegrzynski>I guess the the the science is the same is

00:43:03.472 --> 00:43:04.429
<v Rory Hadden>I, you're absolutely right.

00:43:04.429 --> 00:43:07.550
<v Rory Hadden>This, for me, the way I look at this is that the science is the same.

00:43:07.679 --> 00:43:16.150
<v Rory Hadden>Um, you know, it's the same heat transfer processes, the same fluid mechanics processes, the same mass transfer issues, the same, uh, chemical reaction problems.

00:43:16.239 --> 00:43:20.389
<v Rory Hadden>So in many senses, I see way more similarities in differences, and I think.

00:43:20.780 --> 00:43:28.565
<v Rory Hadden>You know, one of these things that, I get a little bit of a, a b in my bonnet about is, you study, you know, structure of fires or wildfires.

00:43:28.565 --> 00:43:29.806
<v Rory Hadden>Well, why not both, right?

00:43:29.806 --> 00:43:32.925
<v Rory Hadden>You know, you're an experiment or a not both right?

00:43:32.945 --> 00:43:38.382
<v Rory Hadden>And I think these sorts of artificial divides that we've kind of created, our, in our community the

00:43:38.503 --> 00:43:39.672
<v Wojciech Wegrzynski>community the Tribes

00:43:39.992 --> 00:43:41.500
<v Rory Hadden>something that I find quite frustrating.

00:43:41.500 --> 00:43:45.019
<v Rory Hadden>I think, you know, the best work is done at the interface of all of these things.

00:43:45.382 --> 00:43:51.715
<v Rory Hadden>and you know, I think that Hmm a lot that, fire scientists can bring to the table, in wildfires and in the discussion around that, and that is happening.

00:43:52.005 --> 00:43:56.275
<v Rory Hadden>Um, don't get me wrong, that's definitely happening, and I think that's extremely positive.

00:43:56.606 --> 00:43:57.606
<v Rory Hadden>and vice versa, right?

00:43:57.606 --> 00:44:04.623
<v Rory Hadden>There's a lot we, need to learn as fire scientists, about wildfire behaviors and, and the ecological aspects and, you know, all those other parts that play

00:44:04.693 --> 00:44:05.132
<v Wojciech Wegrzynski>role in this

00:44:05.143 --> 00:44:05.382
<v Rory Hadden>problem.

00:44:05.382 --> 00:44:11.440
<v Rory Hadden>So, what I prefer to try and look at this problem is one or more of, of commonalities than, than differences.

00:44:11.847 --> 00:44:14.050
<v Rory Hadden>now of course, that brings challenges.

00:44:14.050 --> 00:44:17.769
<v Rory Hadden>When you start getting to the, the kind of application edge of this.

00:44:17.769 --> 00:44:22.409
<v Rory Hadden>If you want to build a model to predict wildfire spread, then you make different assumptions.

00:44:22.409 --> 00:44:29.996
<v Rory Hadden>And if you want to build a model to predict, you know, fire spread, in microgravity or fire spread on a facade or whatever, and that's normal, I think.

00:44:30.416 --> 00:44:52.489
<v Rory Hadden>But the, the fundamental Hmm approach to studying this, and the, the approach that, that I've tried to take, in the work I've done is or been involved in is to, you know, how much can we apply the techniques and the methods of fire science into these, wildland fuels, that the moisture content is super important, but that in a way is, is it's not simple to deal with, but you can view that as an, an energy sink.

00:44:52.489 --> 00:44:56.130
<v Rory Hadden>So you've got an energy part of the problem, uh, with the moisture, and

00:44:56.199 --> 00:44:58.489
<v Wojciech Wegrzynski>you've got the fluid A actually, sorry.

00:44:58.489 --> 00:45:02.690
<v Wojciech Wegrzynski>It's, it's, it's very similar to what we've just discussed as, as fire retardant.

00:45:02.690 --> 00:45:07.695
<v Wojciech Wegrzynski>Another way to, to dissipate the heat that doesn't go into heating up your fuel

00:45:07.786 --> 00:45:14.826
<v Rory Hadden>there are in in terms of some of the, the, the moisture content problems, that is a very nice way to think about it as, as more or less a heat sink.

00:45:15.056 --> 00:45:21.489
<v Rory Hadden>Some of the other, work that's going on in your should, it's a little bit more complex in the sense of, you know, is it free water or is it somehow bound?

00:45:21.489 --> 00:45:22.130
<v Rory Hadden>And, and

00:45:22.610 --> 00:45:23.219
<v Wojciech Wegrzynski>Mm-hmm

00:45:23.250 --> 00:45:25.010
<v Rory Hadden>implications does that have?

00:45:25.010 --> 00:45:29.210
<v Rory Hadden>And I'm not sure we've fully resolved, that there's some re nice work going on around it.

00:45:29.210 --> 00:45:37.286
<v Rory Hadden>But, in the end, for some fuels, for example, if you have dead fuels aren't living, that simplifies the problems hugely.

00:45:37.295 --> 00:45:42.405
<v Rory Hadden>Um, and we spent a Hmm with, with dead fuels, um, because of that simplification.

00:45:42.545 --> 00:45:46.333
<v Rory Hadden>But of course wildfires don't only burn in dead fuels, they also burn in these live fuels.

00:45:46.333 --> 00:45:47.052
<v Rory Hadden>So we need to think.

00:45:47.525 --> 00:45:47.686
<v Rory Hadden>that.

00:45:47.686 --> 00:45:51.373
<v Rory Hadden>So there's huge similarities there in terms of the porosity, issues.

00:45:51.523 --> 00:45:55.228
<v Rory Hadden>I think that's something that, is perhaps less well, uh, understood.

00:45:55.615 --> 00:46:07.460
<v Rory Hadden>there's again, really nice work around that, I think is now becoming more, mainstream perhaps, you know, work in the US Forest Service that's looking explicitly at linking the burning of wooden cribs to poorest fuels.

00:46:07.519 --> 00:46:19.635
<v Rory Hadden>And that goes all the way back to the kind of genesis of some of these wildfire models, which were all kind of developed using, wooden cribs or these sort of like manufactured synthetic porous materials.

00:46:19.969 --> 00:46:23.789
<v Rory Hadden>and for me that, that's something that's really interesting cuz it, it also puts you on.

00:46:24.003 --> 00:46:28.063
<v Rory Hadden>The edge of having a flaming fire and a smoldering fire.

00:46:28.219 --> 00:46:36.570
<v Rory Hadden>uh, as soon as you bring in this ity, so you change also the, the mode of burning, as well But we don't shift it into a world that we don't understand.

00:46:36.570 --> 00:46:42.289
<v Rory Hadden>I mean, we've been studying smoldering combustion, you know, since the 1950s, uh, if not since before then.

00:46:42.655 --> 00:46:43.896
<v Rory Hadden>and we understand all these things.

00:46:43.896 --> 00:46:53.016
<v Rory Hadden>So for, for me, wildfire and propagation of wildfires, if you look at it through the lens of fire safety, engineering, there's a lot you can, you can contribute.

00:46:53.036 --> 00:46:56.576
<v Rory Hadden>And, you know, it's, it's not the only way of solving the problem.

00:46:56.606 --> 00:47:02.295
<v Rory Hadden>I, I, I'm wise enough, uh, and old enough to recognize that, you know, there's more than one way to skin a cat.

00:47:02.485 --> 00:47:03.775
<v Rory Hadden>but there's a lot that we can do.

00:47:03.775 --> 00:47:11.003
<v Rory Hadden>And I think that, that for me has been one of the, uh, the most interesting, parts of my, my career so far is, is looking at how far you can push that.

00:47:11.195 --> 00:47:14.987
<v Rory Hadden>which of our fire engineering techniques, make the most sense in these different settings?

00:47:14.987 --> 00:47:24.800
<v Rory Hadden>You know, measuring the heat release rate, for example, that's still a pretty good way to go to try to understand, the Hmm or moisture content on, on the burning of fuels, measuring the mass loss rate.

00:47:24.800 --> 00:47:33.521
<v Rory Hadden>You know, these are things that we do all the time, in fire science that help you to understand, um, how these different materials are gonna burn.

00:47:33.521 --> 00:47:35.601
<v Rory Hadden>So from my point of view, there's not really a difference.

00:47:35.601 --> 00:47:39.936
<v Rory Hadden>I mean, I, I, I wear these two hats because I feel like I'm, Hmm made to wear these two hats.

00:47:40.233 --> 00:47:46.358
<v Rory Hadden>when you talk to people, you know, or wildfires are somehow different from structure fires, but I don't know, it's the same hat and just turn backwards,

00:47:46.628 --> 00:47:46.748
<v Wojciech Wegrzynski>guess.

00:47:47.335 --> 00:47:47.824
<v Wojciech Wegrzynski>Okay.

00:47:48.047 --> 00:48:00.257
<v Wojciech Wegrzynski>I, I had an episode with, with Sarah McAllister on the podcast, and we were talking about de combustion different scales, and at some points we also ventured in this weird place where I was talking about opening factors in combatant fires.

00:48:00.398 --> 00:48:09.418
<v Wojciech Wegrzynski>She was talking about foresting Cris, and we've realized it's essentially the same thing in the end, how air can penetrate your source of fire.

00:48:09.668 --> 00:48:14.737
<v Wojciech Wegrzynski>So, so, uh, it, it, it also reaffirms your, your view that it, it's the same thing.

00:48:14.737 --> 00:48:23.740
<v Wojciech Wegrzynski>It's just just a little different, scale or different, application of, of the knowledge, um, for, for the end, something that was mentioned here many times, uh, measuring fires.

00:48:23.740 --> 00:48:29.117
<v Wojciech Wegrzynski>I, I think that's, uh, that's also a fascinating thing to understand how does one actually measure fire?

00:48:29.117 --> 00:48:32.518
<v Wojciech Wegrzynski>I, I think maybe, uh, you'll agree, but I, I think.

00:48:32.860 --> 00:48:42.880
<v Wojciech Wegrzynski>The moment where fire scientists achieved ability to measure fire in terms of it release rate was, uh, one of the biggest turning points in the history of the discipline.

00:48:42.911 --> 00:48:49.831
<v Wojciech Wegrzynski>Like we've finally received a tool that can, quantify the fire itself, not the consequences of it

00:48:50.476 --> 00:48:54.481
<v Rory Hadden>Uh yeah, I mean, I think The ability to measure the energy that's released by a fire.

00:48:54.481 --> 00:48:59.077
<v Rory Hadden>I think it did our way to look as a paper, by Babrauskas isn't there?

00:48:59.077 --> 00:49:03.197
<v Rory Hadden>That says, you know, heat release rate is the most important variable in fire science or something like that.

00:49:03.197 --> 00:49:04.077
<v Rory Hadden>It's, is the title.

00:49:04.257 --> 00:49:38.478
<v Rory Hadden>And I think that goes back to the conversation we were having before about how the energy release drives so much of the feedbacks and the other processes um, that are going on and the ability to measure know, came I suppose once, uh, the diagnostics had become sufficiently advanced I guess in the seventies and, and in the, the early 1980s, in order to measure it using the technique of oxygen consumption, Caltrate, which, is, you know, it's a pretty, uh, robust method, of measuring Hmm Um, that's based on an understanding of the chemistry, at one end, and then the ability to measure the amount of oxygen that has been.

00:49:39.302 --> 00:49:42.032
<v Rory Hadden>Consumed by the reaction, uh, on the other end.

00:49:42.163 --> 00:49:46.512
<v Rory Hadden>So if we tackle the chemistry bit to begin with, that's pretty fundamental in terms of how this works.

00:49:47.090 --> 00:49:53.000
<v Rory Hadden>is that, you know, for most things that we burn from a chemical point of view are pretty similar, right?

00:49:53.170 --> 00:49:55.400
<v Rory Hadden>They're made of carbon, mm-hmm hydrogen.

00:49:55.552 --> 00:49:57.672
<v Rory Hadden>sometimes they have some oxygen in there as well.

00:49:57.882 --> 00:50:00.592
<v Rory Hadden>Of course, we have exotic things that will have other stuff.

00:50:00.592 --> 00:50:10.432
<v Rory Hadden>You know, PVC will have some chlorine in it and, and, um, you know, polyurethane will have some nitrogen in there, but mostly these things are made of carbon, and oxygen.

00:50:10.856 --> 00:50:17.590
<v Rory Hadden>and if you understand the way that energy's released in a fire, I mean, it's made by breaking bonds, for which you have to put energy in.

00:50:17.920 --> 00:50:24.829
<v Rory Hadden>Um, and then bonds reforming, um, to make new molecules in the case of a fire that's usually carbon dioxide and water,

00:50:25.050 --> 00:50:25.318
<v Wojciech Wegrzynski>Hmm

00:50:25.318 --> 00:50:31.219
<v Rory Hadden>uh, the reason that a fire, can spread and can grow is because it releases more energy than it requires to break those bonds.

00:50:31.829 --> 00:50:36.590
<v Rory Hadden>So, if you think of Hmm terms of those chemical, uh, terms, you know, you've got fuels that are.

00:50:37.039 --> 00:50:41.199
<v Rory Hadden>Broadly, quite similar products of combustion that are basically always the same.

00:50:41.199 --> 00:50:44.159
<v Rory Hadden>You know, carbon dioxide, carbon monoxide, maybe some water.

00:50:45.079 --> 00:50:48.840
<v Rory Hadden>and, and what we're actually looking at are the, the ratios of bonds, right?

00:50:48.840 --> 00:50:49.920
<v Rory Hadden>How many bonds do I break?

00:50:49.920 --> 00:50:51.599
<v Rory Hadden>How many bonds do I form?

00:50:51.853 --> 00:50:57.929
<v Rory Hadden>and once you start breaking down to that level, you can see, well again, there's more similarities and differences between the fuels.

00:50:58.376 --> 00:51:00.239
<v Rory Hadden>and, you know, some work was done.

00:51:00.239 --> 00:51:03.320
<v Rory Hadden>I think actually the first work was done like a really long time ago.

00:51:03.409 --> 00:51:05.550
<v Rory Hadden>Um, and I can't remember, the, the paper

00:51:05.840 --> 00:51:10.179
<v Wojciech Wegrzynski>but some um, was by Thornton Thornton

00:51:10.190 --> 00:51:15.079
<v Rory Hadden>Um and he found that basically you always get the same amount of energy per, kilogram

00:51:15.139 --> 00:51:15.820
<v Wojciech Wegrzynski>of oxygen.

00:51:16.235 --> 00:51:17.726
<v Wojciech Wegrzynski>That's like 1920s.

00:51:17.726 --> 00:51:20.365
<v Wojciech Wegrzynski>That's, that's really a hundred years old Uh piece of work

00:51:20.425 --> 00:51:23.980
<v Rory Hadden>it took, the guys at NIST a little while, I guess, to figure out, um,

00:51:24.289 --> 00:51:26.829
<v Wojciech Wegrzynski>to make the diagnostics work on How exactly.

00:51:27.039 --> 00:51:27.460
<v Rory Hadden>and,

00:51:28.340 --> 00:51:28.829
<v Wojciech Wegrzynski>Yeah

00:51:29.019 --> 00:51:38.972
<v Rory Hadden>so in the 1970s or so, once we had the ability to measure oxygen concentrations, in a relatively simple way, we were able to develop this idea of the oxygen consumption calorimetry.

00:51:39.250 --> 00:51:46.179
<v Rory Hadden>and really, I mean, you simply, you measure how much oxygen you have in the air, which is normally always 21%.

00:51:46.400 --> 00:51:54.353
<v Rory Hadden>And then you ignite something and you keep measuring the air, And as you burn the object, you reduce the amount of oxygen that's in the exhaust stream.

00:51:54.492 --> 00:52:02.052
<v Rory Hadden>And, you know, by doing some calculations to turn concentration into a mass, you can figure out how much energy, is released.

00:52:02.635 --> 00:52:07.280
<v Rory Hadden>the magic number that you need to convert, between all of this is something that you hear fire scientists talk about a lot.

00:52:07.280 --> 00:52:11.320
<v Rory Hadden>This so-called 13.1 megajoules per kilogram, of oxygen.

00:52:11.545 --> 00:52:12.264
<v Rory Hadden>it's an average.

00:52:12.335 --> 00:52:14.545
<v Rory Hadden>I mean, some materials it's a bit higher.

00:52:14.545 --> 00:52:15.985
<v Rory Hadden>For some it's a little bit lower.

00:52:16.248 --> 00:52:24.338
<v Rory Hadden>but in terms of ability to make the measurement, usually that's good enough and it's also really powerful Mm we don't have to worry about what we're burning anymore.

00:52:24.427 --> 00:52:32.864
<v Rory Hadden>if you're burning individual pure materials, then fine, you can go and look up, you know, is it 13.1, 13.2, you know, is it 12.9?

00:52:33.264 --> 00:52:33.385
<v Rory Hadden>Whatever.

00:52:33.565 --> 00:52:37.344
<v Rory Hadden>But if you're burning something like couch or you know, something that

00:52:37.545 --> 00:52:37.704
<v rory>is

00:52:37.704 --> 00:52:39.465
<v Rory Hadden>a, a composite or made of many

00:52:40.070 --> 00:52:40.630
<v Wojciech Wegrzynski>Bagel.

00:52:41.264 --> 00:52:43.184
<v Rory Hadden>13.1 number is, is then very useful.

00:52:43.478 --> 00:52:48.460
<v Rory Hadden>it also means that, you know, we have to take these measurements in that context, you know, there's may be no sense

00:52:48.655 --> 00:52:49.266
<v Wojciech Wegrzynski>Mm-hmm

00:52:49.621 --> 00:52:49.820
<v rory>places

00:52:49.820 --> 00:52:51.420
<v Rory Hadden>the heat release rate of your fire.

00:52:51.751 --> 00:52:53.804
<v Rory Hadden>but technique is so powerful in letting us.

00:52:54.800 --> 00:52:55.039
<v Wojciech Wegrzynski>some

00:52:55.050 --> 00:52:57.170
<v Rory Hadden>handle on that, that fire size.

00:52:57.480 --> 00:52:59.016
<v Rory Hadden>there's a lot of tricks in there though.

00:52:59.016 --> 00:53:03.016
<v Rory Hadden>The, the, the process is not one that is super easy to follow.

00:53:03.076 --> 00:53:08.293
<v Rory Hadden>And, you know, I would encourage people to go and look at the original work and, unpick that calculation.

00:53:08.505 --> 00:53:18.903
<v Rory Hadden>there's a lot in there that is, translating from the general concept that I've just described to implementing it, to making those measurements Hmm technologies um, that's not quite so straightforward.

00:53:19.074 --> 00:53:22.784
<v Rory Hadden>Um, but that's the jive of it, I think, you know, is, is finding these devils in the details.

00:53:23.159 --> 00:53:38.349
<v Rory Hadden>the other way to measure heat release rate that I think is really powerful as well is just by measuring the weight of the thing that's burning And if you measure the mass of it, and we know roughly the heat of combustion, that gives you a separate way to try and, evaluate the energy that's being released.

00:53:38.559 --> 00:53:40.670
<v Rory Hadden>Um, again, that can be quite complex if you're burning.

00:53:41.364 --> 00:53:44.385
<v Rory Hadden>not pure materials because what is the heat of combustion of a couch?

00:53:44.385 --> 00:53:45.144
<v Rory Hadden>I mean, I don't know.

00:53:45.385 --> 00:53:48.525
<v Rory Hadden>but you know, it can give you a sanity check, uh, on these numbers.

00:53:48.860 --> 00:53:49.278
<v rory>and

00:53:49.628 --> 00:53:55.425
<v Rory Hadden>I think the nice thing about the mass loss technique is, is that something that you can, deploy at different scales, right?

00:53:55.594 --> 00:53:57.704
<v Rory Hadden>Um, and it's relatively easy to do that.

00:53:57.985 --> 00:54:09.795
<v Rory Hadden>So one of the things, Hmm coming back to my time in, the wildfire world, one of the things I've been trying to do there is, you know, which of our usual techniques can we take out of the lab and into the woods?

00:54:10.007 --> 00:54:23.251
<v Rory Hadden>uh, we can't put a giant, extraction system on top of the forest that we would need to Yeah heat release rate by oxygen consumption color imagery, but we can maybe put a load cell, uh, underground, you know, build a platform and put a load cell there.

00:54:23.262 --> 00:54:25.492
<v Rory Hadden>So the mass loss technique, I think.

00:54:25.735 --> 00:54:26.704
<v Rory Hadden>It's pretty useful.

00:54:26.742 --> 00:54:29.829
<v Rory Hadden>from that point of view, uh, it's, it's a little bit more adaptable.

00:54:29.860 --> 00:54:31.190
<v Rory Hadden>It's a little bit more robust.

00:54:31.190 --> 00:54:33.190
<v Rory Hadden>You know, you only need to make one measurement.

00:54:33.190 --> 00:54:35.349
<v Rory Hadden>There's only one piece of hardware that you need.

00:54:35.690 --> 00:54:43.867
<v Rory Hadden>so I think, you know, looking at, at the techniques and, asked the question of, of, our, um, ability to measure fires has improved massively.

00:54:43.996 --> 00:54:45.226
<v Rory Hadden>Um, which it totally has.

00:54:45.356 --> 00:54:50.940
<v Rory Hadden>Um, but I think the other thing we have to remember as scientists is you know why do we want to make the is going on here?

00:54:50.940 --> 00:54:55.927
<v Rory Hadden>And, Hmm it comes to measuring fires, I always think that, there's two levels of the measurement.

00:54:55.927 --> 00:55:04.166
<v Rory Hadden>There's like the global measurement, so that could be the heat release Hmm Um, for example, uh, in a wildfire it might be the rate of spread in the wildfire.

00:55:04.536 --> 00:55:11.699
<v Rory Hadden>Um, and mm really things to characterize a fire, but then always interested in the next level down.

00:55:11.699 --> 00:55:14.018
<v Rory Hadden>You know, why is that the spread rate that we have?

00:55:14.039 --> 00:55:16.219
<v Rory Hadden>Why is that the heat release rate that we have?

00:55:16.478 --> 00:55:28.811
<v Rory Hadden>And that's where we we're able to kind of pull back on all those ideas we talked about in terms of, know, what is the flame, uh, understanding the, the processes that drive a flame, understanding the heat transfer mechanisms that result in the feedbacks.

00:55:28.942 --> 00:55:33.909
<v Rory Hadden>So we're, we live in an age where, you know, people before us made it easy to make these measurements.

00:55:34.048 --> 00:55:37.668
<v Rory Hadden>Now what I think the Hmm we're living in is the, is the why.

00:55:37.668 --> 00:55:41.429
<v Rory Hadden>You know, why is that the heat relief rate, why is that the rate spread of a wildfire?

00:55:41.429 --> 00:55:44.268
<v Rory Hadden>Why is that the rate spread, um, on our facade?

00:55:44.268 --> 00:55:46.789
<v Rory Hadden>You know, why is that Hmm growth rate in my timber compartment?

00:55:47.168 --> 00:55:55.199
<v Rory Hadden>And I think those questions are much more interesting Forms of question than just, you know, how big or how fast or whatever.

00:55:55.242 --> 00:56:02.208
<v Rory Hadden>because once you know the why, you can then actually start to engineer systems and products and materials much much better

00:56:02.293 --> 00:56:14.764
<v Wojciech Wegrzynski>There, there's one more way, which is extremely hot, but I know there was an attempt, like technically it's a release of so by solving the complete heat transfer of your whole thermodynamic system of your compartment, you can do that.

00:56:14.764 --> 00:56:18.244
<v Wojciech Wegrzynski>And there was this Edinburgh Tall Building, uh, experiment.

00:56:18.583 --> 00:56:24.599
<v Wojciech Wegrzynski>I think Juan made a quite a decent attempt on figuring out from heat transfer, but, but that, that's hardcore, uh, right.

00:56:24.599 --> 00:56:26.000
<v Wojciech Wegrzynski>It's, it's not easy to solve that

00:56:26.065 --> 00:56:30.824
<v Rory Hadden>I think we have to think carefully about what measurements do you want to make and why, you know?

00:56:30.824 --> 00:56:38.199
<v Rory Hadden>Cause if you want to solve Yeah that way, you need to make a very different set of measurements then, if you want to solve it in a different way.

00:56:38.199 --> 00:56:39.994
<v Rory Hadden>And this is for me is now the hard part.

00:56:39.994 --> 00:56:42.114
<v Rory Hadden>Cause we do have a lot of toys at our disposal.

00:56:42.114 --> 00:56:50.873
<v Rory Hadden>You know, we've got lots of different Yeah things, you know, mass loss, temperature, heat flux, uh, energy release, you know, whatever we can, we can do it.

00:56:50.873 --> 00:56:51.114
<v Rory Hadden>Right.

00:56:51.114 --> 00:56:53.514
<v Rory Hadden>The, you know, we can even shine lasers into flames

00:56:53.664 --> 00:56:54.384
<v Wojciech Wegrzynski>look at the structure.

00:56:54.827 --> 00:56:58.161
<v Wojciech Wegrzynski>you can see where the, uh, ions are in the flame.

00:56:58.161 --> 00:56:58.641
<v Wojciech Wegrzynski>Exactly.

00:56:58.641 --> 00:57:00.242
<v Wojciech Wegrzynski>Like, oh, age group, where is it?

00:57:00.242 --> 00:57:03.492
<v Wojciech Wegrzynski>And you, you can actually map that in, in real time It's amazing

00:57:05.277 --> 00:57:11.643
<v Rory Hadden>question I always end up coming back to is, do you want to do it how does it help you to take a step forward?

00:57:11.643 --> 00:57:18.003
<v Rory Hadden>Because, you know, sometimes I think the most difficult thing is having lots of data and then not being able to see the wood for the trees.

00:57:18.003 --> 00:57:18.364
<v Rory Hadden>Right.

00:57:18.574 --> 00:57:23.059
<v Rory Hadden>So I think bit of experience that I've, uh, developed over the, the years is,

00:57:23.119 --> 00:57:23.320
<v Wojciech Wegrzynski>is

00:57:23.594 --> 00:57:32.121
<v Rory Hadden>really hard ahead of time about the measurement that you want to make, make that measurement really well, and then try to compliment that measurement, in the context of your problem.

00:57:32.121 --> 00:57:34.481
<v Rory Hadden>Because these days, yes, we can measure everything.

00:57:35.164 --> 00:57:36.565
<v Rory Hadden>question is, is it desirable to do that?

00:57:36.565 --> 00:57:38.125
<v Rory Hadden>You know is it going to actually help you?

00:57:38.295 --> 00:57:42.485
<v Rory Hadden>Um, do you have, you know, three years to spend crunching through all that data or whatever.

00:57:42.574 --> 00:57:46.945
<v Rory Hadden>So I think, you know, we, we've moved on from the age how to make the measurements.

00:57:46.945 --> 00:57:48.505
<v Rory Hadden>Now I think as I've said it's about

00:57:48.644 --> 00:57:49.764
<v Wojciech Wegrzynski>about what do those measurements.

00:57:50.005 --> 00:57:50.425
<v Wojciech Wegrzynski>Why?

00:57:50.501 --> 00:57:51.255
<v Wojciech Wegrzynski>Fantastic.

00:57:51.565 --> 00:57:52.885
<v Wojciech Wegrzynski>that was a fantastic journey.

00:57:53.335 --> 00:57:58.360
<v Wojciech Wegrzynski>It might be my new, one of the favorite episodes,. Thanks Rory for that.

00:57:58.704 --> 00:58:02.664
<v Wojciech Wegrzynski>I would like to, place an advertisement  on your behalf.

00:58:02.675 --> 00:58:13.675
<v Wojciech Wegrzynski>Uh, I know that University of Edinburgh is starting a new masters in, f you already had a structural one, like you are very well known for a structural curse.

00:58:13.724 --> 00:58:20.074
<v Wojciech Wegrzynski>So maybe you can, uh, tell anyone listening who, who would like to, to pursue a formal education in fif engineering.

00:58:20.074 --> 00:58:22.355
<v Wojciech Wegrzynski>Uh, what what's in the offer from Edinburgh Nowaday

00:58:22.590 --> 00:58:26.204
<v Rory Hadden>you as you said, yeah, we've, had an MSC since the 1970s.

00:58:26.429 --> 00:58:31.739
<v Rory Hadden>um, the MSC started by, uh, Doug Drysdale, professor Rasbash and, uh, Eric Merchant.

00:58:31.923 --> 00:58:35.746
<v Rory Hadden>and we have a long history of teaching fire, um, in Edinburgh.

00:58:36.489 --> 00:58:46.108
<v Rory Hadden>uh, what we've launched for, students starting in 2023, um, is a new, version of that MSC that I think, reflects more the needs, of fire engineering today.

00:58:46.900 --> 00:58:47.300
<v Rory Hadden>the MS.

00:58:47.550 --> 00:58:53.476
<v Rory Hadden>C focuses on really delivering, a solid, grounding in the basics of, of fire science.

00:58:53.728 --> 00:58:55.880
<v Rory Hadden>the, the MSE is called fire Engineering Science.

00:58:55.889 --> 00:59:03.800
<v Rory Hadden>So it's, um, really trying to put at the forefront of fire engineering the, the concepts and the scientific principles that underpin the discipline.

00:59:04.090 --> 00:59:13.619
<v Rory Hadden>Um, so, you know, we draw on, know, areas of, of combustion heat and mass transfer, and of course the fire engineering itself, you know, how you apply, uh, these sorts of things.

00:59:13.719 --> 00:59:13.960
<v Wojciech Wegrzynski>of things

00:59:14.300 --> 00:59:20.094
<v Rory Hadden>uh, we also have, as, as part of the, the class as, as part of the degree, practical work in laboratory as well.

00:59:20.094 --> 00:59:34.693
<v Rory Hadden>So, you know, being exposed to making the kinds of measurements you've been speaking about, understanding the complexities of that, understanding the value of some measurements, um, under different contexts, looking at standardized test methods, as well, you know, and, and analyzing the data from them.

00:59:35.559 --> 00:59:40.018
<v Rory Hadden>So, hopefully, an exciting kind of, broad, uh, education in fire engineering science.

00:59:40.079 --> 00:59:40.958
<v Rory Hadden>, so the graduates can

00:59:40.958 --> 00:59:41.079
<v rory>go

00:59:41.079 --> 00:59:49.070
<v Rory Hadden>into careers where, you know, they're talking about, the important concepts of fire science that underpin the issues around, whether it's timber, buildings, facades, wildfires.

00:59:49.070 --> 00:59:53.849
<v Rory Hadden>Really the idea is to try and create the broadest possible, spectrum, uh, for fire engineers.

00:59:53.849 --> 00:59:55.289
<v Rory Hadden>And so we're excited about it.

00:59:55.300 --> 00:59:59.112
<v Rory Hadden>Um, we'll make sure that the link is in the, podcast episode somehow.

00:59:59.322 --> 01:00:04.072
<v Rory Hadden>Um, if people are interested in finding out more or applying or, or they can of course feel free uh to get

01:00:04.092 --> 01:00:14.891
<v Wojciech Wegrzynski>to get in touch And, yeah, you heard the man, the masters, program is, is this exact podcast episode by, but spread out over two years and filled with amazing content just

01:00:14.952 --> 01:00:15.072
<v Rory Hadden>year.

01:00:15.072 --> 01:00:15.552
<v Rory Hadden>Just yeah

01:00:15.612 --> 01:00:15.891
<v Wojciech Wegrzynski>yeah.

01:00:15.911 --> 01:00:16.492
<v Wojciech Wegrzynski>one year.

01:00:16.492 --> 01:00:16.744
<v Wojciech Wegrzynski>Okay.

01:00:17.728 --> 01:00:19.153
<v Wojciech Wegrzynski>Rory, thanks for doing this.

01:00:19.153 --> 01:00:20.990
<v Wojciech Wegrzynski>It was amazing, talking to you

01:00:21.090 --> 01:00:21.760
<v Rory Hadden>Alright

01:00:22.675 --> 01:00:26.844
<v Wojciech Wegrzynski>And that's, it's a very brief introduction to combustion in the flame for fire safety engineering.

01:00:26.875 --> 01:00:28.014
<v Wojciech Wegrzynski>I hope you've enjoyed that.

01:00:28.405 --> 01:00:31.105
<v Wojciech Wegrzynski>Let me know what you think about this type of content.

01:00:31.105 --> 01:00:33.804
<v Wojciech Wegrzynski>And I'll, we'll try to bring more if you like it.

01:00:33.981 --> 01:00:40.641
<v Wojciech Wegrzynski>There's so many subjects that could be covered in this way with, uh, some, all stars of the fire discipline.

01:00:40.641 --> 01:00:41.365
<v Wojciech Wegrzynski>I always found it.

01:00:41.378 --> 01:00:44.947
<v Wojciech Wegrzynski>Very interesting to learn the basics from the best.

01:00:45.367 --> 01:00:49.148
<v Wojciech Wegrzynski>It's usually very interesting experience to actually try and listen.

01:00:49.177 --> 01:00:54.277
<v Wojciech Wegrzynski>What the world's brightest minds have to say about the most fundamental phenomenon.

01:00:54.487 --> 01:00:55.777
<v Wojciech Wegrzynski>You always learn something.

01:00:55.838 --> 01:01:00.807
<v Wojciech Wegrzynski>As I said, I have learned lots during this interview and I have enjoyed talking to Rory a lot.

01:01:00.858 --> 01:01:05.117
<v Wojciech Wegrzynski>So I hope that this type of content can be interesting for any type of fire engineer.

01:01:05.507 --> 01:01:07.547
<v Wojciech Wegrzynski>I don't think there's much to add in here.

01:01:07.847 --> 01:01:13.697
<v Wojciech Wegrzynski>Um, outside of three books debts, you definitely should have on your, on your bookshelf.

01:01:13.697 --> 01:01:16.668
<v Wojciech Wegrzynski>I'm going to link this, uh, titles in the show notes.

01:01:16.967 --> 01:01:19.307
<v Wojciech Wegrzynski>That's an introduction to fire dynamics, Bali duel.

01:01:19.338 --> 01:01:21.228
<v Wojciech Wegrzynski>A little Drysdale and absolute classic.

01:01:21.273 --> 01:01:30.152
<v Wojciech Wegrzynski>There are fundamentals of fire phenomenon by Quintiere and Enclosure Fire Dynamics by Quintiere and Karlsson three magnificent books that cover.

01:01:30.452 --> 01:01:32.733
<v Wojciech Wegrzynski>So many aspects of fundamental fire engineering.

01:01:32.733 --> 01:01:36.992
<v Wojciech Wegrzynski>And if in your career path, you've never had the chance to go through them.

01:01:36.992 --> 01:01:44.972
<v Wojciech Wegrzynski>I absolutely recommend that because there's no many other places in the world of fire science where you can learn as much as reading through this masterpieces.

01:01:45.349 --> 01:01:47.210
<v Wojciech Wegrzynski>Anyway, I won't prolong this too much.

01:01:47.210 --> 01:01:48.829
<v Wojciech Wegrzynski>I'm still recovering from my flu.

01:01:49.103 --> 01:01:53.123
<v Wojciech Wegrzynski>Has every good employee I took my week off after Christmas.

01:01:53.123 --> 01:01:53.512
<v Wojciech Wegrzynski>And.

01:01:54.143 --> 01:01:55.193
<v Wojciech Wegrzynski>And Colton nasty flu.

01:01:55.373 --> 01:01:56.753
<v Wojciech Wegrzynski>So I spend most of it in bed.

01:01:57.172 --> 01:01:59.161
<v Wojciech Wegrzynski>It's still recovering, but It's going good.

01:01:59.346 --> 01:02:04.346
<v Wojciech Wegrzynski>so yeah, I'll go back to rest and, hope to see you here back in next Wednesday.

01:02:04.465 --> 01:02:10.465
<v Wojciech Wegrzynski>And there's another episode waiting for you and next week's going to be quite interesting for the podcast.

01:02:10.465 --> 01:02:10.856
<v Wojciech Wegrzynski>I think.

01:02:11.096 --> 01:02:13.286
<v Wojciech Wegrzynski>So you rather don't want to miss that.

01:02:13.346 --> 01:02:13.826
<v Wojciech Wegrzynski>Cheers.

01:02:13.856 --> 01:02:14.215
<v Wojciech Wegrzynski>Bye.