261 - The story of the Cone Calorimeter with Vyto Babrauskas

Why Cone Calorimetry Matters

Wojciech Wegrzynski 0:00

Hello, everybody. Welcome to the Fire Science Show. If you have ever used a cone calorimeter, raise your hand right now, or if you've ever used the reports coming from cone calorimeter, used it as a data input for any of your analysis or relied on it to understand flammability of a material, well, that means you're a fire engineer because that, that's what we do, and, uh, cone calorimeter is one of the most used, most fundamental tools that, uh, we have. And, due to its compact nature, uh, robustness, and, kind of ease of use, it probably is the first piece of equipment I would buy if I was starting a new fire laboratory today. And, you know, for such an important piece of infrastructure, I thought it would be cool to invite, uh, again, Dr. Vyto Babrauskas to the podcast to discuss how this tool, uh, came to life. And, uh, and that's what I'm having for you today. I think it's quite a treat to listen about the age of discoveries, '70s, '80s, Vyto was at NIST back then, and that's not the only device that was developed, uh, in there, and we also discuss a little bit about that. We discuss about the climate in which these tools were developed. What were the ideas behind them? what was the need that drove them? And, uh, also-- Well, the record's also written. Vito has written the papers about this, which you are free to read, but I'll, I'll-- I've tried to, ask some questions, you know, regarding the design choices because I, I was very curious about them. Why the sample is 10 by 10? Uh, how about the orientation choices? How about the heat fluxes, et cetera? So I think I got a little bit more complete, overview on the-- not just the background of why Cone Colorimeter was created, but also On why particular choices Went into the machine that you know and, and use today. It was a beautiful time at NIST, golden era of fire science, filled with, uh, discovery, filled with, bright minds. Vyto says it was the largest the team has ever been at NIST. There were multiple teams at NIST, and that's also a part of this podcast episode. And, yeah, I think it just, uh, is nice to know our history. And here I invite you to, to listen this piece of history of our discipline, uh, with Dr. Vyto Babrauskas. Let's spin the intro and jump into the episode.

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Wojciech Wegrzynski 3:02

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The 1970s Problem Of Measuring Fire

Wojciech Wegrzynski 4:03

I am joined today by Professor Vyto Babrauskas. Hello, Vyto

Vyto Babrauskas 4:07

Good morning

Wojciech Wegrzynski 4:08

Hey, th- thank you for taking the invitation, uh, to the podcast. And, today's, uh, topic of the discussion will be around the, uh, cone calorimeter, which, uh, you're basically the author of, this technology that today so many of us, so many engineers, young researchers, old researchers, all kinds of researchers and engineers use. I just thought it could be quite fun to discuss where it came from. so I, I don't even know where to start. How did it look like in the '70s when this technology was about to be born? What was the landscape before the cone calorimeter?

Vyto Babrauskas 4:47

Well, let me kind of tell you a starting point which is not in the official NIST, uh, records, but

Wojciech Wegrzynski 4:55

Okay

Vyto Babrauskas 4:56

where, you know, we started and, uh, I was a-- to coming to NIST, I was a student at Berkeley, Which was a very good experience, the way. It was, like, the right time and the right place to be studying fire science in that era. one, time we had a visit through, uh, Professor Williamson into the lab by a, famous engineer by the name of Rexford Wilson, and, he was a early, person in the profession who felt that, uh... Because you see, to go before, like, before my era, we did have fire protection engineering, but it was, purely code compliance insurance company support activities.

Wojciech Wegrzynski 5:46

Mm-hmm.

Vyto Babrauskas 5:46

Uh, there, there was no science in there. And, uh, Rex Wilson, he was known as Rex by everybody. Uh, uh, he felt that, the fire protection engineering needs to have a, a science base. and he was, uh... There weren't all that many people who were having similar views, so he was rather unusual in, offering that viewpoint. And, So he came into the lab, he met me as a young, uh, graduate student there, and he, felt that, I should be able to do good things later on in, in my career. And so, uh, he says to me, What is the most important, task we have to do in, uh, developing fire protection engineering?" And then he answers his own question by saying, "We have to develop quantitative ways, to measure the, size of the fire and to quantify that as, uh, engineering variable." And I, I can still remember to this day that we, go in the lab and we kind of get a rolling start. What we do is we, um, burn some small things and then we grab a handbook on, heats of combustion. And so we look to see long something took to burn, how much, uh, mass it weighed at the beginning of the and then look at the handbook on heats of combustion and an estimate of how much heat was released in the process. So it's a very crude, uh, start. You know, we can do it for some small things. So the, uh, laboratory at the university wasn't really set up for studying heat release rate. They, they basically had, uh Three rigs. They had an, uh, ASTM E119 wall furnace, a full-scale, ASTM-compliant wall furnace. They had a, ASTM roof test apparatus. Uh, again, this was, uh, standard, full-scale compliant. And then Professor Williamson had built a, room corner, rig, and that was, uh, at that time, non-standard. It was his experimental Uh, much later after I, finished there, he actually developed that further and then basically the equivalent of a ISO 9705 room there. So I was hired by, NIST or they were called National Bureau of Standards at that time. And, that, by the way, tell people, that was the high-water mark the fire, um, research there. was, uh, the phone directory had, I believe, 124 names in it, which was maximum it ever had. It had already started in, uh, 1974, which was, uh, uh, a few years before I got there. and What had happened was a sort of a conjunction that the, there was something called the Products Research Committee, and that was the, uh, upshot. there was a famous, uh, government activity, which my professor, Brady Williamson, had been organizing, which was a lawsuit that the f- US Federal Trade Commission launched against, something like 24 plastics manufacturers And ASTM for deceptive, selling of, uh, plastics, uh, products. And, uh, the basis was a, uh, test ASTM test where they were allowed to, slow burning or, I, I forget what the exact terms were. uh, low combustibilities or something like that.

Wojciech Wegrzynski 9:57

Mm-hmm

Vyto Babrauskas 9:58

In terms of, descriptor, an authorized descriptor of the, plastics. And, the Federal Trade Commission thought that that was way over, over the top and, inappropriate. Uh, but they also had some, uh, issues, uh, with, very long-standing, um, E84 standard tunnel test,

Wojciech Wegrzynski 10:24

Mm-hmm

Vyto Babrauskas 10:24

'cause they also felt that that had some role in, improper marketing. So the, Upshot of all of that was a settlement between the Federal Trade Commission and, these companies, plus ASTM. Uh, it's obviously not a plastics company, but it had the unique role of being a, um, a standards, uh, And, there were-- One of the terms of the settlement was that there was to be a products research committee, where, research would be done to the fire safety of plastics

Wojciech Wegrzynski 11:01

Mm-hmm.

Vyto Babrauskas 11:01

and So there were some, funded research projects, but there was also a cadre of industry, plastics industry people that were to be sent to NIST to, uh, they were to be, you know, seconded into there for a number of years carry on this research on the of the NIST, uh, And so when I arrived, the, there was a reason for the high water mark is because, uh, it was, uh, sort of, uh, government employees, but there was also, maybe, I'm not sure what, 45% or something, were non-government employees where the, uh, PRC,

NIST’s Golden Era And Plastics Research

Vyto Babrauskas 11:50

seconded staff who were, to be doing the plastic safety research. Uh, so it was a very fertile, fertile period and had, very good management. And by the way, so the, the manager was a chemist, uh, by the name of John Lyons. And, there was-- I don't know if, uh, people have heard of, but it was kind of famous, this thing called the Peter Principle. And, it's basically said will rise to your level of incompetence in a bureaucratic organization. So what happened is that Dr. Lyons was absolutely best, remarkably good, uh, director of the Center for Fire Research, uh, that the center had. And then he had a series of upwards, uh, promotions and eventually became the head of NIST.

Wojciech Wegrzynski 12:55

Okay

Vyto Babrauskas 12:56

then eventually, he was removed as the head of NIST because there was a, uh, long published in The Washington Post newspaper That to the new, president, I forget who the new president was, but "Dear Mr. President, you are inheriting a bureaucracy with a number of deadwood, administrators, and here is a list." I mean, it's remarkable. They published like a page-and-a-half list government people who should be removed because they are not, effective in the job they are doing. And John Lyon's name was on that list, and he was removed. the, uh, and the reason, I mean, I, I felt that that was, uh, appropriate because, conformed to the Peter principle that he started out being remarkably effective as a manager, then he went to the top and became remarkably

Wojciech Wegrzynski 13:53

Beautiful.

Vyto Babrauskas 13:54

as a, a top manager. And, basically, that was never written, but my summary was, if you do something, you can get into trouble. you do not do something, then you cannot get into trouble. So take your guidance from this, uh, uh,

Wojciech Wegrzynski 14:15

Uh

Vyto Babrauskas 14:15

perspective. I don't think that's a good perspective myself, but, uh,

Wojciech Wegrzynski 14:20

Yeah.

Vyto Babrauskas 14:21

Anyhow, so

Wojciech Wegrzynski 14:23

That's, I'm not sure if I want, uh, our younger colleagues to follow that advice, but it's, uh, advice from a much more experienced, uh, colleague who, who've seen, who, who've seen that. a l- a lot of interesting timelines clashing in here from the plastics industry with their testing programs, you, uh, finishing your education at Berkeley, going to, to NIST, uh, NIST being in a perfect, uh, place, uh, to, to do all of this. One thing I need to understand when Rex Wilson talked to you, y-you, you here used to say the, the, the phrase, uh, he said, "We need to measure fire." Was it obvious that heat release rate is the measure you are looking for?

Vyto Babrauskas 15:02

right. That's right. And you see, we were not yet-- term heat release rate was not yet, uh, fully, uh, developed.

Wojciech Wegrzynski 15:11

Hmm?

Vyto Babrauskas 15:12

so, you know, sometimes I would be instructing people, How big is the fire?" Because everybody understands that. And then, you know, the engineering term would be heat release rate, but, you know, people called it energy release rate. You can call it, uh, output rate. You can, uh, some people call it rate of heat release. So, know, the, uh, one of, you know, in 1992, me and Steve Grayson were... edited this first and only book on heat release in fires, and that was really the time that we adopted the idea for that book, it must be called heat release rate not something else, uh, just to make standard the because, uh, and you know, you sort of look at it from today's viewpoint, becomes especially more important because if you're gonna do a web search on something, you don't wanna search, uh, a of different terms. You wanna search a specific term. it was the, the book in 1992 where we really made firm that that is the term and not, these equivalent terms.

Wojciech Wegrzynski 16:32

W- while I cannot put the whole book in the in the show notes of the podcast episode, I'll can also to the listeners, I'll link it to Vito's paper, "Heat Release Rate: The Most Important Variable in Fire," which, uh, which also g- gives, I guess, the condensed version of the story. I mean, I, I, I ask that because now if, if you ask me today, "Uh, could you design me a, a way to measure the size of a fire?" "Oh, you mean heat release rate." I mean, that already guides your whole thinking process. But h- how could you define how big is the fire? You can say how hot is the fire, what the temperatures it produces, how tall is the fire, how much mass loss do you have, the enthalpy, uh, analysis.

Vyto Babrauskas 17:12

yeah. That's right.

Wojciech Wegrzynski 17:13

S- so,

Vyto Babrauskas 17:13

So

Wojciech Wegrzynski 17:14

in-

Vyto Babrauskas 17:14

let me give you the context because, you know, it's, it's also sort of interesting that... when I got hired into there, you know, you have to have a specific, division and, a group that you're assigned to. So I, I was hired into the furniture flammability group,

Wojciech Wegrzynski 17:30

Okay

Vyto Babrauskas 17:31

that was, um, uh, interesting because they had, uh, just, fired some people from there for not being able to, uh, finish the project. So I came there and they-- uh, it was, uh, uh, these people were a- uh, k- kind of curious in hindsight, they were able to do, good lab work. What they weren't able to do is write a report.

Wojciech Wegrzynski 17:58

Mm-hmm.

Vyto Babrauskas 17:58

it turned out that I was good at being able to, write, uh, reports. So had no problems, you know. There's a big pile of data and, uh, write a report. Sure, I mean, why not? That's, uh, pretty easy for me. Well, apparently there's a, you know, it surprised me that there's a, a lot of people for whom it's very, very difficult. Anyhow, so, you know, I, I first, uh, got these projects to finish where I wasn't in charge of the lab work, but I had to write the report. So I wrote the report, and it became clear that, you know, what's missing is the ability to measure the heat release rates. Now, uh, so, but I was, you know, still working in this group where the name was Furniture Flammability Group, that was what was paying my uh... But you see, in that era, because we had really good, uh, management, uh, what the managers felt is that who's a staff scientist who has good ideas and, uh, has a plan on how to execute them, you just let them be, let them do their thing. which I later learned is not, uh, always the management,

Wojciech Wegrzynski 19:20

Oh, that's very rare. That's very, very rare

Vyto Babrauskas 19:22

L- later on, the manager- management got given over to people who were, you know, like the old Soviet Union, the five-year plan. I was never living in the Soviet Union, but I can appreciate the, strangeness of the five-year plan. So anyhow, the, um, the other extreme. But so in that, in that era, things were, were, were very good. And so I decided that, you know, what's missing to make further progress is, good tools for, uh, release rate, even though-- So I was, I was not working as a instrument designer. I was working as, you know, a researcher in furniture flammability. I just needed tools.

Wojciech Wegrzynski 20:08

Could you, could I ask you to tell me a little bit more about what existed? Because I find it in the literature, I don't find that much about, about it, and I find some interesting things, enthalpy substitute burners, et cetera

Early Calorimeters And Why They Failed

Vyto Babrauskas 20:20

Yeah, exactly. Okay, so le-le-let me sort of paint the picture this way. So first of all, what we identified early on and, and I think that was sort of mostly my work, is that need to do things in three scales: bench scale, in, what, you know, the, you would now call the single burning item scale

Wojciech Wegrzynski 20:43

Hmm?

Vyto Babrauskas 20:44

and, the room fire scale. And I think, you know, to this day, that is, uh, appropriate. So you have three different scales and all of them need, equipment. Now, the... I had no role to play in the room, fire measurement development, you know, the, the actual, what became, uh, ISO 9705 because, what we had, we had a researcher at, uh, uh, NIST, uh, by the name of Jin Fang, uh, we had some more work done by another researcher named Billy Lee, and then we had Professor Williamson had by that time gotten contracts or grants to, uh, study, uh, room scale, develop, develop a room fire test with each release rate. So I was not in that picture. What I was in the picture for the other, uh- The other two scales, uh, the, bench scale and the, whole item scale. Now, the-- this is an interesting story, which I think is-- will be very helpful to people in a sense. So you see, from Berkeley, I came with a, a combustion background that, that, uh, you know, I was in interdisciplinary track, but the, the heaviest, uh, exposure was to combustion science So I came there with a combustion methodology And so you see, w-well, the reason why that's important to say that because the existing orientation in the profession was widget testers. In other words, we have some sort of idea of something, we're gonna make some tester. And I was completely opposed to that idea coming from the combustion background. What I felt is, and you see, combustion science kind of had a blank spot because it, it was mainly focused on, gas phase phenomena, a little bit on liquid fuels, but, uh, nothing on, solid, objects that simply-- and they hadn't gotten to that time and place of covering it. But it was clear what, you know, what the principles would be. you have to make a X by delta Y slice of something, and you have to have conditions over that slice, and then you can start reporting results are per meter squared or per millimeter squared or whatever. And then that will, uh, be a somewhat scale-independent, assessment. you see, that, that is a combustion science perspective did not exist in the, fire protection engineering world. I, proceeded to drag that in there. And, uh, the... Now, in terms of actual hardware You know, th-there were a number of people who had various widget testers. There was a, uh, what was a, an NBS, uh, substitution burner calorimeter.

Wojciech Wegrzynski 24:15

Yeah

Vyto Babrauskas 24:15

There was an Ohio State University, uh, calorimeter by Professor Ed Smith. Uh, there was this, uh, Archie Duarsan at, uh, Mutual had this, uh, round specimen, which is a very difficult, of course, to manufacture and all that. But anyhow, round specimen that in, in his, uh, apparatus, the Tewarson apparatus. think th-those are the main ones. Now, I need to also tell you the story So you see, I, I became a very good instrument designer. I was not a, uh, instrument designer, when I came there. So how did that happen? Well, it happened because I became very, good friends with a scientist named John Tordella. And, uh, John Tordella Was a professional instrument designer from the DuPont company, and he was part of this BRC, uh, that, uh, uh, were there.

Wojciech Wegrzynski 25:26

PRC as the Product Research Committee that was, uh, brought to life after the plastic thing.

Vyto Babrauskas 25:31

That's right, that's

Wojciech Wegrzynski 25:32

Okay. Mm-hmm.

Vyto Babrauskas 25:32

Th-those-- So he was part of that industry, you know, the forty-five percent out of the hundred and twenty-four headcount or something. He was one of those, uh, people. And, you know, and, and that, varied. I mean, there were some people who were sort of literally hiding in a dark room and doing nothing. But at the other end of the scale, there were people who were very active, and he was maybe the most active and, mean, I, I basically apprenticed with him and learned how to do instrument design uh, having lunch day with John Tordella and learning how to design instruments from him. Now, So there's a story there too, because he designed a, heat release rate calorimeter, uh, which there is a single report, uh, with, uh, John Tordella and Bill Twilley as the authors, in this, uh, Tordella calorimeter. I forget what the official name was. it was in this substitution burner, principle. In other words, you, uh, basic registering, um, sensors are, uh, thermocouples, but you, um, put in a specimen, and there was a hydraulic, or a pneumatic, rather, elevator that, uh, went up. And then, you know, you had the specimen burning, and then you had the gas flame burning, and you, uh, ma-made the equivalence

Wojciech Wegrzynski 27:07

Well, so what's the equivalence? Like you measure temperatures from your sample of...

Vyto Babrauskas 27:12

Uh, uh, all right, let's back

Wojciech Wegrzynski 27:13

it's very abstract today, Vito. Like I it's interesting but abstract

Vyto Babrauskas 27:17

the, the crudest, uh, way measure the heat coming out of a fire simply to measure the flow enthalpy with thermocouples. Okay.

Wojciech Wegrzynski 27:29

Mm-hmm.

Vyto Babrauskas 27:30

Now, the problem with that is that, there's a huge amount of, uh, errors that you cannot w-with a instrument that you can Uh, you cannot account for the heat flow. Uh, you know, if you have every, every wall instrumented in every place and then, uh, a computer program to, uh, do the conductive heat transfer into every wall, yeah, you could do that, but that's, uh, costly to instrument. So people typically have just a couple of thermocouples and try to,

Wojciech Wegrzynski 28:05

Figure out

Vyto Babrauskas 28:06

yeah, run it off of that. And so there's So, uh, Ohio State University, apparatus, that-that's how it works. a thermocouple in the stack, and you, uh, you stick in a burner, and you say, well, reference to the burner, and you forget about the fact that, uh, the specimen may be polystyrene, and that has a very different radiant characteristic from your methane burner. So different things happen inside. Now, so the substitution ver-- but, you know, I don't wanna go too much into that because it's really a dead idea. Nobody uses that today an-anymore. But so anyhow, so the-- he built this, uh, apparatus. Uh, uh, what I learned, though, is-- you see, the apparatus took up two rooms. Uh, one was the room with the calorimeter, the other room was the room with a giant air compressor, which was needed to run that.

Wojciech Wegrzynski 29:04

Okay.

Vyto Babrauskas 29:05

uh, what immediately became obvious-- So it was a learning lesson to me. What became obvious to me-- So I started formulating. You know, nobody gave me instruction. I just decided I'm gonna have some fundamental specifications the instrument that I'm gonna design. And one of the specifications is that, it must sit on four wheels and be able to be wheeled into a truck. Uh, you know, I felt that if you do that, you cannot, sell the idea to some other laboratory that isn't your own laboratory. I mean, to me it was obvious, but you know, it wasn't obvious. So, anyhow, so the Tordella machine was, uh, you know, ran one series of tests and it was torn down, and then they put our, uh, toxicity lab in there, and I became in charge of the toxicity people, so we were killing rats in that room, uh, later on. But what, uh-- To, to me, you know, because while John Tordella may not have been, sensitive to some issues, was nonetheless a instrument designer, I needed that, uh, training, to, be able to become a, competent instrument designer myself. And, you know, I had the benefit of learning from things that he didn't do as a ideal, uh, in

Oxygen Consumption Calorimetry Returns

Vyto Babrauskas 30:40

an ideal way. So, that time, the concept of oxygen consumption calorimetry was very, uh, new and very important. And, uh, uh, Clayton Huggett wrote this paper where he, said, you know, 1917, uh, Professor William Thornton, who by the way a polymath, person, you know. I later when I wr- you know, when I write my electrical book, he did a lot of work there.

Wojciech Wegrzynski 31:10

Okay

Vyto Babrauskas 31:11

so Thornton. So, uh, Dr. Huggett, um, uh, rediscovered, uh, what Thornton had learned in 1917, he published this pa- paper in the Journal of Fine Materials "Hey, we should, uh, that." Thornton just wrote this as kind of, uh, curiosity. When, uh, Huggett said, uh, uh, "No, it's more than curiosity. We should run and do things with it." Uh, he was, uh, in a management role. He did not any opportunity to do anything in the lab, and I did. the-- But we had, uh, had a number of, you know, people, on that. We had a- another PRC person named Daryl Sensenig, who was, uh, doing experiments, uh, in, uh, making sure that the heat release rate, uh, concept got debugged. I was able to, uh, from, from what he was doing

Wojciech Wegrzynski 32:08

I- if I can stop you for, for a second because I, I find this really interesting. Y- y- you, you're also like, you know, uh, uh, fixing some holes in my own, uh, perception of things in history of fire. I used to have an idea that, uh, Thornton discovered this, this, um, th- this principle on oxygen consumption when materials burn, uh, wh- which is true, and there's like, uh... I, I've actually... The, the-- His paper from 1917 is available online, the beauty of internet. There's a huge table where he calculates the molecular combustions and everything, uh, how much oxygen they consume, et cetera. But I had an idea that the-- since he published that, it has became, obvious knowledge from that point, and now you bring that it was kind of rediscovered by Clayton Huggett, who brought, uh, "Okay, there's this interesting concept, now we can actually use it."

Vyto Babrauskas 32:58

And absolutely, that's right. For the next, or 60 years or whatever, there was absolutely nobody had ever referenced and nobody had ever done anything with it. It was completely, forgotten. Yeah. So, uh, and I don't know how-- You remember that was way before the internet, so I'm not sure how Huggett, rediscovered that. Uh, you know, you couldn't go to Google Scholar and type things in in that era. So he rediscovered that paper, I'm not sure, but he did. And, he came from the, um, aerospace, uh, industry, uh, him and Bob Levine were two managers at that time who were, uh, from the, aerospace, uh, so obviously that's a pretty heavy duty sector and, uh, Anyhow, so that's, uh, So I soon realized that oxygen consumption would be the, the tool that we were gonna use both in the cone calorimeter and in the furniture calorimeter.

Wojciech Wegrzynski 34:05

you also measured mass loss rate, so you, you already had access to heat of combustion and, uh,

Vyto Babrauskas 34:10

Well, you see, okay, uh, so I'm gonna keep separate the cone

Wojciech Wegrzynski 34:14

Yeah

Vyto Babrauskas 34:14

furniture calorimeter because, you know, the cone calorimeter was really, in my conception, it was primarily combustion science equipment.

Wojciech Wegrzynski 34:25

Hmm

Vyto Babrauskas 34:26

It would be, turned out to be very useful in the fire safety engineering profession, and I, I don't think it really shows up much in textbooks today. It shows up in, uh, safety textbooks. But still, you know, my orientation, because I had come from the combustion work at Berkeley, was to make something that would be, uh, in a combustion lab. and as you may know, I mean, combustion labs are-- The single most important word is diagnostics, okay? So, they are, typically dedicated to a lot of different things in some test, uh, arrangement. And so I took that mentality and said, know, mass loss rate, of course, heat release rate, smoke production, toxic gases, and then we can also do, uh, ignition data. so we really cover, uh, a lot of, uh, properties but that became because it was from a combustion uh, point Now, uh, you know, maybe

Designing The Cone Heater And Ignition

Vyto Babrauskas 35:50

I should tell people a little bit about, uh, the hardware. You see, hardware is actually kind of, uh, difficult when you think about it because back to the, you know, the criteria that I made for myself that you have to have a s- an X by Y specimen with uniform And, uh, that's a lot easier said than done, because typically what people using was panel type heaters. You know, how, how do you heat a specimen? Well, typically they would have like a gas-fired, uh, panel. So the Tordella instrument had gas-fired burners. Uh, the, uh, original NIST calorimeter had gas-fired burners. The, uh, Archie, uh, Tewarson unit has, uh, quartz lamps. uh, i- it's a very, uh, interesting and difficult question how to heat it that you have uniform heating. And of course, you know, what you gotta remember is that you're gonna have ignition, and then there's gonna be

Wojciech Wegrzynski 36:59

Mm-hmm.

Vyto Babrauskas 36:59

flames up there, and that still must not, cause you big trouble. So it was very, you know, serendipitous. at the, across the hall me, I had one of these other, um, industry PRC people by the name of Ted Stolze. he came from BASF. And, He, and by the way, my boss had come from BASF also, you know, who became then a government employee. So he given a, ISO 5657 rig, uh, which was ISO Ignitability apparatus, which has a cone heater.

Wojciech Wegrzynski 37:43

Mm-hmm.

Vyto Babrauskas 37:43

Uh, that was something that was, developed by Steve Grubitz in Australia, and I only learned about that later on. What I, did, you know, when I was actually doing the work, I had not yet found this, that there was a small that Steve Grubitz wrote, but, you know, the Australian research reports, have never been easy to get, uh, I think they're very difficult to get now. what, uh... So I had this, uh, apparatus across the hall from me that, that Sils was running, and I had a draft of the, ISO 56, uh, 57 standard. So looked at it and said, "You know, that's a, a good idea." then I started, so I got my own, uh- Set, and I started playing with it, and I realized, well, it's a good idea, but nothing's right with the hardware. Uh, because first of all, I wanna drive this up to kilowatts per square meter, and I could only drive it up to 60 in, uh, that particular way. what it was, uh, i-it wasn't, you know, it's an ignitability test, so they don't care what happens after ignition. Well, I do. You know, I had the big...

Wojciech Wegrzynski 39:07

You care exactly what's happening after the ignition, right?

Vyto Babrauskas 39:10

So the, what turned out is that, uh, combustion products would mushroom out over the heater, which of course you don't want to do. You want them to go up in the middle. And so the idea of having a heater a good idea, but you had to redesign it so that it would go up the middle rather than mushrooming out the sides. So that's, you know, I made a, a modified cone that there's a straight section in the bottom, and then it, uh, goes conical, and that allows the end products of combustion to get sucked up in the middle so they don't, uh, over the edges. Now, they also had a-- And, you know, I, I, I'm not, uh, uh, faulting anybody for what they did because they did, you know, had the best ideas at that time, but they, you have to progress. And they had this, what we call the dipping duck pilot, you

Wojciech Wegrzynski 40:13

Mm-hmm.

Vyto Babrauskas 40:13

which, uh, it's, uh, mechanically a clever idea. But, you know, again, being... coming from the combustion science world, from that world, it's a very bad idea because you wanna get, the ignition time to a fraction of a second, not to plus or minus five seconds or whatever. So Uh, that was obviously not what I was going to use. uh... And, and this was really the-- up until that point, the really felt that, ignition, you always ignite things with a small pilot flame. and I thought about it, and I was thinking: "Well, yeah, you can do that, but in some cases, it may be better to have an electrical, uh,

Wojciech Wegrzynski 41:02

Okay. Yeah. Mm-hmm.

Vyto Babrauskas 41:03

uh, like you have in, gasoline, uh, motor engines. so the, uh-- Now, obviously, you need a-- I can't just grab one from, uh, uh, automotive because I need a, a certain, electrode configuration. But Then I discovered that there are some, industrial combustion systems which do need, long electrode, igniters. Uh, and so, uh, I was able to, uh, harness that and, to, uh, put that into, uh, into, into play. And, uh, so eventually, it, it all, you know, it came through just in the right time because they had a, management change in, I think, roughly 1981. And, uh, when I was sort of, uh Partway through, uh, the development work. what was, uh, real interesting was, uh, just before that, so when I was actively doing the work, uh, the, uh, John Lyons went, promoted, and then his deputy, Clark, took over as the, uh, director of the Center for Fire Research. And from my perspective, he was also a very good, uh, because he knew to leave us alone they were, uh, if we were doing good work. And so there was this very funny, uh, in that, uh, where, uh, we had this... I, I think some people know there was a guy named Bud Nelson, uh, that was, a section chief for another section, uh, not, you know, related to where I was working. But he, he, he went to this, uh, boss, Fred Clark, and he said, "You know, there's this guy, Vito Babrauskas, who's doing very stupid things. He's trying to invent something that can't be done, and you ought to check into that, and you ought to government dollars from being wasted on,

Wojciech Wegrzynski 43:18

Uh.

Vyto Babrauskas 43:18

uh, this kind of stuff." So uh, Fred Clark, uh, being, uh, uh, uh, what I felt a good manager, he, uh, calls me and he, calls Mr. Nelson and a, a number of other people, I think Randy Lawson maybe, I'm not sure who else, like, uh, say, you know, "What, what's, uh, uh, we... I have this complaint that, people are doing bad things with government money, so I need you to what's happening in, in your lab." And, uh, so I, I explain and, he does understand and, then everything is, uh, you know, he basically tells me, "Well, keep doing what you're doing. It looks to me like you're gonna, uh, be, uh, uh, finishing up something that's, uh, that's useful." So, you know, I did encounter some resistance, uh, and, v-very strange because, uh, you know, I-- there was no real, Mr. Nelson was not, uh, he was not involved in a-- he did not run any labs. He was doing, uh, uh, system analysis type of, uh, work. anyhow, he decided he didn't like what I was doing. But the, what, what I was very grateful for is that, uh, uh, you know, if this would've happened like one year later, if I would've gotten started with the next management after, after Fred Clark, I would have gotten nowhere because, uh, you know, nobody would have had the cone calorimeter in their five-year plan. f- so I was just finishing up as the new management was taking over, and it, it was pretty obvious that, you know, this was, uh, work and they, uh, gonna, uh, stop it. But, uh, they certainly wouldn't have started it, had that been the management at the time

Why The Sample Is 100 By 100

Wojciech Wegrzynski 45:20

it's so interesting to hear about those clashes among people who we now all consider legends. Like, it,

Vyto Babrauskas 45:25

yeah.

Wojciech Wegrzynski 45:26

it's kind-- I, I find it kind of interesting. Um, uh, again, I have a question about stuff that's not necessarily directly written in the papers. Um, the scale of the sample. So you said that you were inspired by the conical heater that came from CSIRO and that, that you've seen, uh, at your floor. So v- and, and you also mentioned that, uh, you want something that has four wheels on and can be moved. but the cone calorimeter is not exactly like, I don't know, TGA apparatus, like, or, or heat of combustion apparatus, where it's just, you know, a, a pure material property. The way what we get out of the cone calorimeter today, a lot of people try to link it to large-scale combustion. So it's like, you know, uh, a full-sized fire but shrinking down to the small sample. Uh, uh, my colleague has done a PhD thesis where he linked, uh, cone calorimeter to room corner tests with quite good degree of success, and I know other people have done that along the l- the years. So it's not just, you know, a tiny physical phenomena versus the full-scale physical phenomena. It's kind of the full-scale physics in the small package. Was that the idea, or it just, uh, luckily happened like that?

Vyto Babrauskas 46:41

Well, you see, okay, the, you know, from a combustion science point of view, it's obvious that you somehow need to study a delta X by delta Y, and that if you do that, then things have to be, pretty uniform over that distance. Now, scale I decided to basically-- and that's a, you know, excellent question. Uh, decided to basically keep the scale of the, uh, iso ignitability apparatus.

Wojciech Wegrzynski 47:13

Mm-hmm

Vyto Babrauskas 47:14

So that has 165 by 165 millimeter, uh, specimen in there. But it's clear that, the edges of that would be extremely non-uniform.

Wojciech Wegrzynski 47:27

Mm-hmm.

Vyto Babrauskas 47:28

So the-- what I worked myself down to is, that 100 by 100 millimeters, uh, is not perfect, but we can get a reasonable enough uniformity that for practical purposes we can, uh, call it uniform. So basically, the scale became, um uh, governed by, the rough scale of the, 56, '57, uh, apparatus. Uh, you know, I changed all its, uh, dimensions because I had to make a different, uh, And oh, the other thing that, uh, you know, you had, the coils would keep drooping out of there,

Wojciech Wegrzynski 48:15

Mm-hmm.

Vyto Babrauskas 48:16

uh, which is a bad problem, so I had to design it so that there'll be less propensity for,

Wojciech Wegrzynski 48:23

う ん。

Vyto Babrauskas 48:23

coils droop out, it's... Now, the other thing I should just mention with that is that the, uh, I think, you know, now of course, people take it for granted, but, uh, this was the very first time, uh, that a feedback loop was incorporated into a fire test apparatus. again, this is all, you know, comes from the combustion science world, not from the fire safety world, that the, uh, once, uh, you gotta look at the, the heat transfer in there. so as soon as the specimen ignites, you are effectively going to make the, heating coils much more efficient because ins-instead of shining down the 298K, they'll be interacting with the, with the flame there. So, how do we keep, uh, the, uh, e-effective radiation, to be pretty constant? you know, and then that was a good error because already in the, uh, the Uh, 1980, uh, timeframe, we were, uh, competent with, uh, uh, feedback loops and PID controllers and, uh, like that. Uh, so the-- I could put in, three thermocouples in there

Wojciech Wegrzynski 49:49

Mm-hmm

Vyto Babrauskas 49:49

and then, uh, connect them to a, uh, uh, a temperature controller so that they have a feedback loop. I mean, that's the first time ever you see that in a, fire test apparatus. And yet, when you think about this, you know, things that, thermal management, that you should be controlling things to be constant, And, and I think still there's very few, places where that is done in, you know, the fire safety world.

Wojciech Wegrzynski 50:19

Okay. A- another question. Have you considered, like how much did you care about this kind of, uh, one-dimensionality of heat transfer? Like how, how did, how did you solve the boundary pro- problem around the corners of the sample?

Vyto Babrauskas 50:35

Well, okay. The, um, what-- first of all, let, let me back up and say the, you know, one thing that was already very much ingrained in my mind was not from the combustion courses, but from, Brady Williamson, that, he was a big proponent of the fire safety of plastics. And, what was learning from him is that these things are likely to sh- to show up as composites or multilayered, uh, products. if things are, composite or multilayered on a really large scale, then of course you can't do it in a bench scale But, uh, most things are, you know, like a mattress, say, or something like that. You know, there'll be different layers, but, uh, it's okay to have a, hundred by hundred millimeter because it'll be representative of what you have in the, in the real world. Now, your-- the answer to your specific question, of what happens in the, the corners, obviously, the-- there is some error in the sense that the, the heating is, uh, fairly uniform, fairly one-dimensional, a big fraction of the hundred by hundred, uh, But, you know, corners do have a, don't behave the, uh, the same way. So the, there is some-- And, and there have been a number of people, you know, in subsequent years who have characterized the uniformity. It's, you know, not, uh, perfect, but, uh, the alternative... You see, let, let, let me back up here a step also. Uh, from the measurement of, um, from the people who wanna measure thermal conductivity, uh, I guess, uh, building science engineers,

Wojciech Wegrzynski 52:39

we call them building phy- building physics people in here

Vyto Babrauskas 52:42

building physics. Yeah. you know, the, some of those apparatuses are built with, uh, guard heaters, the guard heaters are, very, cumbersome technology. So uh, I decided that, uh, the results are, uh, uh, gonna be okay without, uh, without going to guard heaters. Now, uh, you know what we did the-- that's sort of a continued, uh, discussion because I just had some with, uh, Uh, E1354 is being revised, and I'm not sure that I like where they're going because the, uh, you know, there is a question of, how do you treat thin samples and how do you treat the in-depth problem? Now, one, uh, decision that I made early on is that it, it was-- does come from the having worked in the furniture, uh, safety area, that I wanna be able to deal with about millimeters depth. That the, I, uh, have a, you know, let's just say, which we don't normally have, but let's just say we have a very sort of a layer cake, uh, type of a, uh, specimen, which has a lot of layers in there. Not tiny, they're substantive layers. So I decided 50 millimeters is a good, uh, depth to encompass. So the idea was to make the hardware so that we can test it up to, uh, 50 millimeters. And people have generally been, uh, okay with that. Where they're raising questions is at the other end of the samples. And, um, generally my answer is that, you gotta focus on your own reality. There's no truly general answer that the, uh, you know, you have options. You can put it over an air space, can put it over a ceramic fiber blanket, or you can put it over something else, you know. In principle, you could put it over a slab of, uh, steel, but

Scaling Bench Data Toward Real Fires

Vyto Babrauskas 55:15

I think that is very done just because that very rarely is a, representation of, the real-life environment. Now, oh, I wanna get back to what you started before about the delta x versus the big thing. Yeah. So the, uh, you know, that's, uh That is, uh, effectively now we're going into the modeling world and, that I felt I really need to leave to people who are going to be more fully immersed in that. In other words, I think there is several ways you can do this. And, you know, I've talked that a little bit in the SFB handbook, in the, heat release rate, uh, section there. The, the simplest, uh, strategy is to simply, you know, take the delta X by delta Y scale it to the area of the real, uh, life situation.

Wojciech Wegrzynski 56:20

f- full scale sample, like kind of

Vyto Babrauskas 56:22

yeah. Now, obviously what that, uh, ignores is any transient, uh, flame spread aspects over the, the, over the surface.

Wojciech Wegrzynski 56:33

And uniformity of heat flux, which is also

Vyto Babrauskas 56:36

That's right. So, you know, if the flame, if the spreads fast, then it's probably pretty good. If the flame spreads slow, it's not good. and then need, um, to do a more refined, uh, modeling. So But you know, uh, from a safety point of view, you know, like for instance, for the furniture where I was getting involved with, I, I have been involved in the, you know, especially the CBAF project to, uh, do some relationship the small scale and the real scale. But the, uh, I felt, uh, so it was-- see, Cone Calorie and the Furniture Calorie basically got delivered at the same time within the space of a few months because they were Strategized at the, the same time. And, uh, the-- for the, the... Oh, let me also mention for historical. So for the cone calorimeter, I really only had, uh... Well, John Tordel inspired me, but the helper was a man named David Swanson, was my technician, and he did the drawings, and he did the shop fabrication and the assembly. So he was a part of things. But then uh, departed the government service, um, very soon at-after the was being finished. And then I was assigned Bill Twilley, who had been doing something else, and he, uh, well, he was working with John Tordel, among other things. then he came to be, uh, my technician in, uh, things

Wojciech Wegrzynski 58:26

Uh, I must say the pictures in the paper with the first earliest version of the cone, the cone looks very professional. So props to your technicians. This is excellent craftsmanship. It looks very, very nice

Vyto Babrauskas 58:38

Yeah. So the man, the man was, uh, you know, he's, he's not really known, but it's David Swanson. His name is somewhere in the report that the, um, he did the work of the drawings and the, the, uh, the Now, at the same time, the cabinet was, you know, physically a little bit harder because it's bigger scale. So I had, two main people that I worked with was Randy Lawson and Doug Wall. And, uh, Randy Lawson originally came the PRC, uh, program, from, I think from the gypsum industry via Armstrong Cork, or I'm, I'm not sure I'm remembering the details. But the-- he then eventually changed his, um, employment. He, he sat in the same chair, but he became a federal government employee for the, uh, the rest of his career. uh, Doug Walton was a federal employee, and he just died recently, somebody, uh, told me. And, and, and uh, they were scientists. Uh, I mean, they were not PhD scientists, but they were scientists, uh, of those people, and good, uh, So to make the, furniture calorimeter, I had the help of, uh, those two, people. So th-there, there was more scientist involvement, you know. I was the sole scientist on the cone calorimeter, but there were, two other, um, science professionals involved with the, uh, the furniture calorimeter

Picking Heat Fluxes For Realism

Wojciech Wegrzynski 1:00:30

Mm, could you tell me more about the, mm, range of heat, uh, fluxes that you've used? So, uh, today it's mostly used by, uh, with 25, 50 kilowatt per square meter exposures as kind of a typical go-to setting of the cone calorimeter.

Vyto Babrauskas 1:00:45

Yeah. Yeah. Okay. So

Wojciech Wegrzynski 1:00:47

W- w- why, why, why not five? Why not 500?

Vyto Babrauskas 1:00:49

Okay. Well, the, uh-- okay, a very good question. Um, So if you go to a flashover room fire, you typically find fluxes of peak around, say, maybe 120 or so. So, and assuming, you know, we don't have, jet fire impingement or other sort of, uh, more unusual, configurations. Um, so, um, 100 kilowatts seemed like it's going to cover not 100% of room fires, but, the vast majority of room fires, and again, excluding uh, process industry where, yes, uh, you know, impingement zone heat fluxes for, uh, jet fires are gonna be vastly more than 100. But, uh, know, I leave that to other people. Uh, the Then, you know, I did, um, studies of, flames, small fires, and what I concluded is that 35 kilowatts per square meter is, um, very common to see as the peak value in those. Uh, you know, there's a lot of exceptions, there's a lot of special cases, but if you just sort of look at something pretty ordinary a small or a small fire, 35 kilowatts per square meter is going to be, um Very common. So in general, I don't like to go below that because I think it lacks realism. Now, you know, if we wanna do ignitability studies, obviously we need to go down as low as, uh, ignition can be done. But, uh, that's a separate, uh, separate, uh, topic. But, uh, if we wanna just have a representative burning, I feel that there is something quite important about thirty-five kilowatts per square meter because corresponds to, a lot of, uh, fires. And the other thing, I, I don't particularly like doing heat release rate testing at twenty-five, even though I've, you know, done some of that. uh, reason is that ignitability can have a too strong a role in that, that in other words, uh, may elicit specimens, uh, the, uh, ignitability or non-ignitability tends to become, important. And again, you know, in real world, yes, that can happen. But, uh, if we just wanna characterize something in broad brush terms, think it's best to not go in that area because, uh, then you get repeatability statistics which become a, issue. You know, if, uh, one specimen takes, uh, ten seconds to ignite and the next specimen takes two hundred seconds to ignite, there's obviously going to be, repeatability issues. So

Wojciech Wegrzynski 1:04:30

Mm-hmm.

Vyto Babrauskas 1:04:31

I think, th- there's a reason to prefer, thirty-five for, for that

Wojciech Wegrzynski 1:04:38

D-d-did you back then already, mm, perceive the potential of, of this knowledge at different heat fluxes for a material? Because it kind of like gave us opportunity to develop pyrolysis models, et cetera. Like, it, it, it, it can tell you so much more about the, the, the burning behavior of a material at full-scale fire that we really need today. But, uh, from the original '84 paper, I mean, you report the data from different heat fluxes, but that link is not explicitly made, I think.

Vyto Babrauskas 1:05:10

Yeah. You know, because I felt that, you know, my role there primarily as an instrument designer.

Wojciech Wegrzynski 1:05:19

Hmm.

Vyto Babrauskas 1:05:19

So I didn't want to set agendas for fire modeling research, because I felt that that's, uh, you know, there's people that are more, focused on that, that can do a appropriate job because they're in it, and I'm not immersed in it. Yeah. So,

Wojciech Wegrzynski 1:05:40

Mm-hmm.

Vyto Babrauskas 1:05:41

Yeah, yeah. But you know, yeah, that's a very interesting, subtle question you know, I view my role as an instrument designer, much more so than as a, promulgating, uh, fire safety, strategies. Because I felt you know, I give people that tool, then there should be a lot of other people who, take it in these different directions.

Wojciech Wegrzynski 1:06:09

Yeah, and there was a

Orientation Choices And Furniture Calorimetry

Wojciech Wegrzynski 1:06:10

lot of people who have taken that in very, very interesting directions. Uh, that, that's a sign of, of designing a really great apparatus, Vito.

Vyto Babrauskas 1:06:18

Yeah

Wojciech Wegrzynski 1:06:19

i-i-if I I have so many more, I'm sorry. The, the orientation, because it's obviously horizontal. You said it, it can be vertical if it's not dripping. did you felt that it's an, a limitation? I mean, in vertical orientation, there is so much more happening in the physics of the, of the fire itself in-- with the sample kind of with, with itself so much more than when you have horizontal and that feedback loop that you've designed

Vyto Babrauskas 1:06:46

Yeah. Yeah. So, you know, uh, th-this was kind of a unique idea that there hasn't been, any other apparatus designed that way, and there still isn't, to be able to do two different orientations. Now, you know, uh, where this makes more sense is that if you look at the being the combustion science world, and, that things are very different in terms of the flame structure and the, in the pool configuration versus in the wall layer. So you know, I view this as, okay, so we basically have two different experiment test beds here. And what I felt, a- and you see historically, horizontal or vertical always been completely different apparatuses. And I was really the first person to have this idea that there's so much similarity that you can make one apparatus and a hinge there, and, do it in a two different, uh, orientations, and all you need is different, uh, sample holders. So you know, this was again, what you see is that, know, I delivered a, combustion science, uh, test, uh, apparatus. uh, with the idea that Safety engineering applications, there will be a lot of people who have different ideas and can do, different things. And, and I, I still am comfortable with, with that, uh, that decision. Now, you know, the furniture calorimeter was a little bit different because that's, uh, the entire, furniture item. So it is, uh, full-scale, results on that. and you see... And, and that was, uh, completely unique idea because there had been some, you know, including these, uh, reports that, uh, somebody else did the work and I got to write the, the report at, uh, NIST. to that, you know, if somebody wanted to study furniture, well, you go into a test room and you throw in the and then you, you burn it and make the test. Now, From, again, from looking at the, the heat transfer and combustion science involved in that, what is clear is that you may get a significant, uh, room effect compared to, open space. And the, uh, open space results I'm not gonna say that they're completely general, but they're certainly, more generality if you have a small room the ceiling layer begins to play a role in, uh, radiant feedback and all that. and I think, you know, it wasn't, uh, my own unique viewpoint. Obviously, the whole organization at NIST supported of view that it is, uh, we, we were pretty excited about, uh, putting the oxygen consumption, methodology to good use, and, putting it to use in measuring burning the furniture seemed like a, natural fit. So that had, uh, wide support. And, and, and, you know, subsequently, I, I don't think there's actually been a great deal of research done, but what we see is that the, mattresses, there can be-- there will be a huge, uh, room fire effect if you test the mattress in a, uh, a significantly burning, not a, you know, not

Wojciech Wegrzynski 1:10:51

English

Vyto Babrauskas 1:10:51

construction, but a significantly burning mattress in the, in the room fire versus in the calorimeter. But, uh, For chairs, it's, uh,

Controlled Atmosphere Cone And Smoke Metrics

Vyto Babrauskas 1:11:00

less, but still it's, You need to be aware of the possibility

Wojciech Wegrzynski 1:11:05

Yeah. I, I have a few more. Um, there's also, uh, I found it interesting, there's a controlled atmosphere, uh, calorimeter in your paper. I've, I've learned that a few years ago that Fartesting Technology has this controlled atmosphere attachment you can buy through the icon and oh man, that's cool. That could open so many interesting research. And then I see your paper, it's already been there in 1990, so that, that's an interesting... But they didn't get too much work done on, on that one, yeah?

Vyto Babrauskas 1:11:32

there's a story to that, that the-- it was basically a Mark II version of the original Compton calorimeter. In other words, it had, everything the original had, but it had a lot more ergonomically friendly, controls and, of course, the whole, feeding the desired atmosphere. And then, uh, at certain point in that, the took this, uh, stance saying that, uh, uh, you gotta sure that this thing isn't gonna up at somebody. So we had to do quite a bit of, safety, studies, and, uh, Bill Twilley was, um, uh, put in charge to, to do that. But, you know, I, I left in, uh, April of 1993, and, so there was one more-- there was one-- paper published on the instrument. There was a paper published with, uh, me and George Mulholland on, some results, and then, uh, there was some work done for the US Navy. And I'm not sure when, but soon after I departed there, management decided, Well, why, why do we need this? Uh, the device is big and we can rid of it and, uh, use the room for something else." mean, you know, you would have thought that they would have gotten rid of the Mark I version, which was indeed, you know, getting older, kept the Mark II version, but they decided to keep the Mark I version and throw out the brand-new one. Well

Wojciech Wegrzynski 1:13:19

Well, okay. That, that's,

Vyto Babrauskas 1:13:22

That's why you don't see-- don't ever see any, uh, additional work there because, uh, we finished that project, they said, "We're gonna scrap that." But I

Wojciech Wegrzynski 1:13:33

Wow.

Vyto Babrauskas 1:13:33

you know, gone, so

Wojciech Wegrzynski 1:13:34

That's a, that, that's a, that, that's a

Vyto Babrauskas 1:13:36

even sure who made those decisions

Wojciech Wegrzynski 1:13:38

pity. L-l-l-last thing on my list, you, you've mentioned George Mulholland just now. I've learned that, uh, the smoke measurements came into the device later. So if you can tell me about introduction of, of this, uh, smoke obscuration measurements, perhaps introduction of Smogra as a parameter as well in that. Because today that's like the baseline. You, you take it for granted as a part of the cone analysis, right?

Vyto Babrauskas 1:14:01

yeah. Yeah, so, you know, ori-- yeah, that's right. that was not, there. And I'm not really sure what, uh... You see, um, one very pivotal thing is George, uh, by himself wrote this paper called something like, "How Well Are We Measuring Smoke?"

Wojciech Wegrzynski 1:14:21

Mm-hmm.

Vyto Babrauskas 1:14:21

And, uh, and Fine Materials Journal. And what he basically there is, "You guys have been doing this all wrong. You have been putting incandescent light bulbs in and the, science us you should be making monochromatic, measurements because if you make just this incandescent spectrum measurement, the data are not as, uh, not have the same amount of validity." So, I took that as good advice But I, I think basically the history at that point was that we simply hadn't gotten around to doing the smoke yet. And once George, uh, out that paper, uh, it became clear, not only sh-- really we do need to measure smoke, but we have instructions from how to do that. And, then what happened is that there was at that point a company called Custom Scientific, which then was sold and doesn't exist for, you know, a long time now. But at that time, they were building the first commercial cones in, uh, America. And so they also, basically came to me and said, need to have smoke measurements." And they helpful in, getting the hardware debugged and At that time, you know, we were already having very inexpensive helium-neon lasers available. but the issue with those devices is that, they do not have, a great baseline stability. And

Wojciech Wegrzynski 1:16:16

Oh, yeah.

Vyto Babrauskas 1:16:17

that was the-- So as you know, the basic design

Wojciech Wegrzynski 1:16:23

They drift like hell

Vyto Babrauskas 1:16:24

yeah, it's a reference cell, type of a design that you ratio it to the reference cell. It's not just a straight-through measurement.

Wojciech Wegrzynski 1:16:34

Hmm

Vyto Babrauskas 1:16:35

And that was because, you know, the affordable helium-neon lasers were not stable enough that you could just a baseline and rely on it

Wojciech Wegrzynski 1:16:46

Affordable lasers today are either not that. Like it, it, they were, we're, we're still being plugged by thermal drift of laser emission or LED diode emission, whatever you like to use to emit your light. It's, it's a, it's a, it's a pain when you want to build a device on your own and you, you get to that point. Uh, but, uh, s- you were obviously interested in hit release rate. I think measuring smoke is an interesting addition from the perspective of completeness of this fire safety, you know, value that you get through the, through the device

Vyto Babrauskas 1:17:20

And you see the, the-- what that also entailed is the contribution, you know, between me and George that the, to this concept of the, uh, specific extinction area because you know, like up to that point, say UL would be measuring smoke in a lot of their tests, and they would be simply transmission over like a five-foot length of, uh, beam, which is not a, it's, it's not an engineering number that has any, computational, applicability. So thinking as a combustion science, uh, perspective, you need to have something that's a material property.

Wojciech Wegrzynski 1:18:12

Mm-hmm.

Vyto Babrauskas 1:18:12

other words, if I, double the airflow rate I, double the irradiance on the specimen, I don't want, value that I report to, greatly change. I want it to be, in some sense, something that is characteristic of the material, divided by delta x divided by delta y.

Wojciech Wegrzynski 1:18:39

Mm-hmm.

Vyto Babrauskas 1:18:39

So, in li- in that case, of course, it proved that it's, uh, mass lo- loss rate is, is the uh, denominator. But, that was the origin of the, the thinking there and then, you know, various other things, uh, sort of piggybacked onto that like- caller smoke, uh, and whatnot So, the idea was that, uh, would have some that has a reasonable amount of non-dimensionalization

Wojciech Wegrzynski 1:19:10

Mm-hmm

Vyto Babrauskas 1:19:11

that, you know, if I were to double or half the specimen size or whatever, it shouldn't have a great effect on the,

Wojciech Wegrzynski 1:19:19

it, it has definitely found a lot of practical use and, and helped us a lot. There's still an ongoing debate on whether that number is, you know, universal for all kinds of combustion. We're also into that, uh, with some colleagues from Germany. The colleagues from Germany were reporting some very interesting

Who Uses The Cone And Why

Wojciech Wegrzynski 1:19:35

findings in that, so... But, but, but we would not get there if, if this was not started by, by George and you. a final question, like you, you've observed this method like being used for 40-plus years. Uh, i-is there like-- If you ca- if you had to pick like one, maybe two studies that surprised you with creativity where people got using the cone, I mean, th-there has been hundreds of people using the cone calorimeter and, and hundreds of people reporting interesting thing. My, my personal, I really enjoy Spearpoint's papers from his master thesis with, with Jim, Anything for you like that?

Vyto Babrauskas 1:20:14

Well, you know, the, the-- just to tell you sort of the big picture, I mean, clearly the people who found this the most, valuable have been, uh, polymer development people.

Wojciech Wegrzynski 1:20:30

Okay

Vyto Babrauskas 1:20:30

Uh, that's just n- that's not my, statement. This is just observing the literature. that's the community that has, uh... And right from the very start, even the very early days, you know, like around 1990 or whatever, the, largest, section have been people who are looking at a, at a relative basis, um, polymers, uh, of various sort. so just in terms of a, a very crude, Evaluation of the output. Now, you know, that's, that's actually not what I would prefer to see, uh, I mean, with the due, uh, due respect to, to that community. the-- What I would like to see more, applications for is in, more direct fire safety engineering applications as, uh, more as part of the toolkit of fire safety engineers. and I think that still is a growth area uh... Because, you know, you, you look at things, okay, from the, ideal point of view, real scale, recreation of some hazard is the best study of the, the hazard. but the economics are, very often not conducive to doing that. So if you're going to do in a much smaller scale, I certainly do think that, uh, doing it in a cone calorimeter a, good way to do that. And, We have seen a lot of work there, but, I don't think we have seen, maybe enough, that, is still a, a big growth area I view as a, from a positive perspective

Wojciech Wegrzynski 1:22:32

I wonder h-how many are there in the world, the cone calorimeters?

Vyto Babrauskas 1:22:37

Well, certainly over 500.

Wojciech Wegrzynski 1:22:39

over 500

Vyto Babrauskas 1:22:40

yeah, that's, uh, fair to say. And, uh, eh, you know, the biggest, um, users are, uh, plastics industry, test labs and, universities. I think those are the three, big categories. And by the way, I don't think, the US is, uh, necessarily any leader in that, uh,

Wojciech Wegrzynski 1:23:08

Yes

Vyto Babrauskas 1:23:08

uh, that area. I mean, it's, uh, there are enough, uh, instruments available here, but I don't think, uh, it has taken as strong a, a role as maybe some other parts of the world

Wojciech Wegrzynski 1:23:21

Well, o- o- one thing I've learned when you start a fire lab, that's like the first thing you buy. So it's a it's a, it's a good starting point and you can get, uh, really, really far with, with, uh, with just it.

Vyto Babrauskas 1:23:33

Well, you

Wojciech Wegrzynski 1:23:33

there-

Vyto Babrauskas 1:23:33

that goes, I think, to the fact that I, I do feel that I made good decisions from the combustion test bed point of view. the... if you, you have a well-controlled, reliable combustion test bed, then you can do a lot of diagnostics, in that, by just, adding either instrumentation or analytical methods and, uh, keeping your test bed. So I think that's, uh, that's kind of the, the big origin of that

Wojciech Wegrzynski 1:24:14

Yeah. And, uh, I mean, having it in such a reproducible manner with so many of those, it also gives fire science a sense of reproducibility, which we don't really have in many other things, especially full-scale tests, right? So I, I think that's also a huge value in the method. And, and on, on your previous thought about you would like to, to see more engineering use, it's not that easy, to be honest. I mean, it's kind of tempting to just measure your heat release rate per unit area with cone and just scale to 100 square meter facade, but we know it doesn't work like that, right? though there's-- I, I know a lot of effort of, of people, like I-- as I mentioned, my colleague who is approximating a room corner w- from a cone, it was reasonably successful. Uh, a lot of people are trying to get Arrhenius-type pyrolysis reactions from the data straight from the cone into your pyrolysis model. Some are going great, some are going not great, but i-i-it's, it's, it's a, it's a development, you know? I think there's, uh, still a lot of stuff that, can help us streamline this, you know, pathway from question through test, which is cone, into the answer that you need to apply in your full-scale project. I see--

Lithium-Ion Battery Research Needs Better Questions

Wojciech Wegrzynski 1:25:30

I, I, I don't see this unit retiring anywhere soon, to be honest

Vyto Babrauskas 1:25:35

you know, now let, let me-- it just occurred to me. me make one comment about heat

Wojciech Wegrzynski 1:25:40

Yeah

Vyto Babrauskas 1:25:40

release rate research, and want to maybe, hopefully encourage people in the right direction that in the last like, oh, you know, good 10 years, you ask what is the single most dominant, research papers in the fire safety profession, I believe the answer is lithium-ion batteries. And I sadly disappointed at the overall low quality of those research efforts, that the... You know, so I, I'm obviously a major proponent of heat release rate, importance. But, what I see countless papers that says, uh, and this will be more likely not in a cone, but in a, uh, you know, a

Wojciech Wegrzynski 1:26:37

General colorimetry spurs

Vyto Babrauskas 1:26:40

scale calorimeter where, somebody went and measured the heat release rate of some lithium-ion battery pack, and there's a graph of time versus release rate. And, that's great, you know, I'm, uh, promoting, uh, heat release rate, but the-- I don't think that's enough. I think, uh, the simply documenting, release rate curves for batteries is not going to create a safer world. So, think, I would urge that researchers in that field do a little more thi-- Like, well, for instance, let me make sort of personal perspective comment. You know, these, these days I, I work largely in the forensic, and explosion, area. the-- one thing that we don't have enough, papers on is on the, forensics of those inc-incidents. In other words, um, the-- you have, uh, some debris where lithium-ion batteries burnt and exploded, and there's some junk on the ground. there's some questions that are, likely to be asked. one important question, for example, uh, was this device the or the victim of the event? And, uh, you know, it's kind of a fundamental starting point question. And even on something that important, you know, we have a few papers, but nowhere near uh, a large collection of papers. anyhow, I would urge people to, uh, working in that area to try to formulate some more insightful not just deliver us papers with a heat release rate graph at the end of it, because good, but not good enough.

Wojciech Wegrzynski 1:28:50

I mean, I'm, I'm not 100, 100% sure how universal oxygen consumption calorimetry is for battery fires as, as, at, at, at, at the core, as a core principle of how you calculate. Perhaps, you know, y- y- hour ago you said the enthalpy measurement is a thing of a past. Maybe that's the thing where we dig it out of the grave and bring it back because that could perhaps in a well-instrumented, you know, space could give you much more detailed information about the, the growth. And there's also like accelerating rate calorimetry that's being used in that space, which obviously is, is a different, uh, a different story. But yeah.

Vyto Babrauskas 1:29:27

And, you know, and I think that-- Well, people can look in my ignition handbook. the-- A lot of these so-called industrial calorimeters, I think are, There are some serious questions about the, um, eh, universality of the data that they return. In other words, uh, you know, those instruments are really not necessarily better than the older thermal analysis equipment. And, not exactly correct to say that if you, a, thermal analysis that you're working with, you can get any number you want by simply selecting a particular data reduction algorithm. there is a lot of truth in that, uh, implication. And, to me, That, that's why, you know, uh, I've written very clearly in the ignition handbook that if you're studying self-heating, uh, problems, which is a very important engineering problem, which is sometimes needing, uh, engineering work, that the, uh, use thermal analysis is, uh, diluted, not, uh, legitimate because if you take the gold standard as being the, uh, FRS oven basket testing, uh, protocol, you do not get adequate correlation to

Wrap-Up, Links, And Listener Email

Vyto Babrauskas 1:30:50

that

Wojciech Wegrzynski 1:30:51

Yeah. Thank you. Thank you so much, Vito. Uh, it's like s- so much more we could discuss about, but let's perhaps, uh, put a pause on here, and, uh, I would like to thank you for, for coming to the Fire Science Show and, uh, telling us the story o- of how this extremely important piece of instrumentation, uh, was brought to the world of fire science

Vyto Babrauskas 1:31:11

Well, you're, you're, you're most welcome. It's, uh, uh, it's a, it's a, it's a good opportunity to, put, put that down so that people who weren't there, uh, uh, way back can have some, some feel for it. Yes

Wojciech Wegrzynski 1:31:24

And you know what? Uh, when you do cone calorimetry tests, uh, the time flies slowly, so listening to a podcast is a perfect way, uh, to, to m- to maintain. I know a lot of people are doing that. So if you were listening to the history of cone calorimetry when, uh, doing cone calorimeter, please write us an email. I would love to hear from you. Okay. Thank you so much. And that's it. I don't really have much to say after this beyond the words of appreciation to Dr. Vyto Babrauskas for spending two hours of time with me recording this interview. there's a paper by Vyto, uh, multiple papers by Vyto, but one that discusses the history of cone calorimeter which is linked in the show notes. There are also interesting press releases from NIST, um, on the, the birthdays of the cone calorimeter, uh, where they also share some information. You can see some more technical pictures of the Mark 1 version of the cone calorimeter. I think it's also nice to go through those. They are also linked in the show notes. And, uh, you know, I, I just think it's necessary to learn our history. We need to be respective towards our history, and we have to understand why some things are like we have them today, because this context is quite important in, in many of our things that we do in our everyday's job. Therefore, I will try to bring more-- a little bit more of that. It's not easy to bring those episodes up, uh, but I'll do my best to try and interview the people do- who created our history, and I will keep going, uh, interviewing people who are creating history as we speak. Uh, thanks so much for being here, uh, with me today, and look forward to next Wednesday where you will get your another dose of, uh, Weekly Fire Science. Thank you. Bye.