Hello and welcome to Technically Speaking, a podcast where scientists and engineers come together to chat about a common interest share knowledge and satisfy some curiosity. I'm Aneeqa and in this episode I'm joined by Rwayda and Laura to talk about fire safety and materials used in fire safety. Rwayda I know you have a background... your PhD was was in fire safety of buildings so can you tell us a little bit about why you care about this topic?
So first I will start this with a question this time, so I will say: would you build a furnace out of timber? Only if you wanted to burn the furnace at the same time as getting heat. Yeah, so basically you just answered your own question about fire safety and why we are
interested in it. So basically we need to use the appropriate material for a specific application so if we need to burn that furnace we will build it out of timber because that timber will be burned or we can glad that with the material that is not flammable and we protect the furnace there's different technical names for fire safety so called fire engineering fire protection engineering or fire safety engineering they all refer to the same thing
that is the science behind how we are making building or other structures safe from fire. Laura, your background's a little different so why are you interested in fire safety?
Yeah you're right my background is very different! Fire safety sits inside the wider spectrum of just general safety science and when I first started in the nuclear industry a long long time ago now I did a lot of courses on how to make things safe not just about radiation but more generally what is called conventional safety and all these courses started off with something that's a little bit like anatomy of disaster which I think is a TV show. I've only heard of Grays Anatomy.
I think that's a bit different. Just a little bit, yeah! Erm, but all these things would start off with looking at like a big industrial incident and the the chain of events that led up to that and kind of showed us that it was never just one thing that caused the incident it was multiple things. Some of these incidents have led to changes in legislation. I mean there was a health and safety at work act in 1974 that had big changes for how people did things and these sorts of things, like,
sort of permeate through society as well. So an example of a really big event that I kind of remember learning about in primary school was the fire of london in 1666 because we were taught the nursery rhyme that went with it so all the safety stuff is sort of... it's part of our society and we don't really think about it that much and I guess a really good example of it fairly recently it was
the 2020 Bahrain formula one grand prix where Roman Grosjean's car crashed in the very first lap and it burst into flames this huge fireball. I'm not much of a formula one watcher but I was really shocked to see it. It was quite scary! The fireball was caused by a fuel system being damaged but amazingly Roman Grosjean got out of his car and walked out with this fireball. He had some burns to his hands and feet and that was about it which I thought was
flipping impressive. All the engineering that went into that to keep him safe! So this guy was literally in a ball of fire and all he had was a few burns on the back of his hands and feet and he walked out of it? That's insane! What makes things fireproof like in that incident? Well the first thing I learned about when I was doing fire safety training was about the fire triangle which essentially says that you need three things to start a fire: oxygen, heat and a fuel. To add to
the resultant reaction must be self-sustaining and that's pretty widely known
in the safety sphere. I have personal experience of that from when I used to eat... well, not eat matches but I used to put matches out in my mouth as a child because of the principles of the fire safety triangle it's starved of oxygen so when it's in your mouth you've created a seal around it the flame goes out and you don't get burnt and your mum doesn't come at you with a cricket bat as we've previously discussed go back to episode i can't remember what episode it was it's the
very first one where you fell out of a tree yeah i mean we're talking about wrists well it's my favorite one so that's my personal experience of the fire triangle so did you know about the fire triangle when you were doing that with the map of course yeah i'm like this is why it's it's been put out when i put it in my mouth it's not getting oxygen and i'm not going to hurt myself i use science in a controlled manner science kept you safe at knowledge can you say definitely yeah
so we talked about this oxygen there i work with chemists quite a lot i should point out right now that i am not a chemist myself so i've picked up lots of chemistry terms from my colleagues over the years they can probably explain this better than i can but if there's oxygen there then that suggests to me the fire is about oxidation so it's a chemical process and when i was reading up on this loads of articles described this in terms of oxygen bonding to things that contain carbon
and hydrogen which are of course hydrocarbons if you have some heat there as well that provides the chemicals with enough energy to overcome some sort of thermodynamic energy barrier i guess and this then starts off the oxidation reaction and the oxidation reaction is exothermic which means it gives off heat and hence that puts more heat into the reaction so it becomes self-sustaining so there's a little bit of chemistry behind why things can be set on fire yeah and i think that's
that's so relevant because we've seen so many like forest fires these days so about the reaction being self-sustaining then it keeps burning can it happen without oxygen being present i know we said that you know we have oxidation but if there's no oxygen can we still have combustion happening i think so because another way of looking at oxidation from chemists again is redox reactions for reduction oxidation so oxidation is essentially loss of electrons right
oil right oxidation is loss reduction is gain is that right yeah i think so that is pretty much what went through my head when i slowed down to think about it an example i saw on a few websites was a reaction between hydrogen and chlorine so if these are sitting around quite happily you'll normally have two chlorine atoms bonded to each other and two hydrogen atoms bonded to each other and they get along fine but if you put some energy in there it creates this redox reaction
so one of them gives off electrons first of all they split into radicals see i've been around chemists for too long and i forget that there are some very weird terms in there i've not been a lot of chemists for too long so i'm having a intense learning experience right now yeah i'm trying to think how best to break this down when i'm so used to talking to kevin so we all know what radicals are of course but a radical is essentially it's usually an atom or it could be fragment of a
molecule it's missing some electrons to make it whole essentially so that makes it really reactive so if your chlorine molecules split apart into individual atoms and then missing electrons that makes them more active or they there is an electron imbalance i shall say so obviously you can oxidize something you can make it lose some electrons there's a good example from the royal society of chemistry where i think they expose a mixture of hydrogen chlorine to light
and that causes it to have this really explosive combustion occurring i think uh it looks like a pretty cool experiment to me thanks laura so as we've already kind of discussed if you remove one part of the fire triangle that should make the chemical reaction stop and and make the fire go out as i have experience of with my matches is that is that always the case or was i just very lucky i think so yeah so from my experience of a non-chemistry thing thankfully i can stop talking
about chemistry a little bit for example if i've been sitting around a barbecue and you're pretty much done cooking but the coals are still there and it's quite nice to sit beside it because it's getting a bit chilly in the evening and those coals are surrounded like a layer of char so if you kick the barbecue carefully special point out you can knock that layer of char off and it gets a lot warmer so that reaction that has been prevented by the the char forming
blocking the oxygen getting to it then makes the reaction continue so that would be the optimum temperature for barbecue without the char yeah i guess so yeah i've never actually thought about barbecue temperatures i feel like i should do some experiments now leave a potato to bake on the charcoal that's what we used to do right on the leftover heat just put loads of potatoes or vegetables and just leave them overnight and then in the morning they'd be really
really yummy so we've talked a bit about the fire triangle and about how fires form so now let's go on to the materials kind of things what's the difference between a fire proof material and a fire resistant material fire proof material it's a material that cannot be burned and fire resistant material is a material that would resist the heat for a certain amount of time then start to fall off and be flammable then my experience as a fire safety structural engineer what we're trying to do
because it's so expensive to have the material to be fully fire proof we will make the requirement to make it fire resistant is basically to give the time to people to escape the building when it would start in flames in this case um so like in building generally if we think back to the fire triangle you'll have the oxygen and you have the heat and you have the material we can't live without the heat or the oxygen can we we need to breathe so we can't remove that from buildings
we can't remove the oxygen and we need the heat otherwise we'll freeze or not eat any cooked food i'm a fan of cooked food i wouldn't want to get rid of that essential heating as well the main thing we could modify to keep the building safe is the material so is having the appropriate material the key thing to avoid a catastrophe if we talk about something as simple as a gliding material do you think it would need a certain sort of requirement to be safe yeah there should be some
kind of requirements for safe materials i know this hasn't always been the case as we've seen a lot buildings have caught fire so i don't think it's always the case but i assume there should be some kind of regulation yeah so if we take for example one of the glading material aluminium composite panels made of thin aluminium layers with polyethylene and polyethylene is a plastic and if we don't get the right amount of material in there it would become flammable because the
plastic is a flammable and if it catches fire it will transfer it which leads us to something else and structural fire safety engineering we call it traveling fire so the fire will travel from one bit of the building to the other bit of the building and the media or the mean in this case will be the glading material so the gladink will transfer fire into bits of the material so we would need to apply a specific regulation to keep these uh material safe for the glading so
this might be a silly question but why was the cladding material made from something that was flammable you get oxygen there it seems like a bad idea because of the cost and safety and also the construction ability of the building it is easy to use plastic to do that it's very expensive to glade it all with aluminum so if you got the amount of the material right so like the certain thickness of the sheets and so on it would be safe it would be totally fine to use but if for
any reason you added a bit more plastic it won't breathe so that's why we have the regulation to specify what is safe and what is not safe and it would be reviewed every now and then seems quite like a fine balance i know that there's so many buildings that have not suitable cladding at the moment and that's a huge problem isn't it for people to change it okay so we've discussed a bit about materials chemistry when it's come to buildings and the
regulations now let's go back to the formula one example that laura gave about grosjean what made what he was wearing fireproof and how did the change come about because i'm sure they've not always used such materials a lot of the fire engineering that relates to ppe started in about the 1960s and it was in relation to racing cars in modern formula one stuff they were an inner body suit called nomex that was developed by a company called i think it's pronounced dupont
but i might be wrong i've only ever seen it written down it's sort of a self-extinguishing fiber and over that roman grosjean was wearing a specially designed outer suit made by alpine stars um and all the suits the racing drivers were they've got proprietary technology in them that they won't talk about in a lot of detail so exactly how they make them fireproof that alpine star suit it might have had air pockets in it that expand in the heat as they provide sort of
a layer of insulation between you and the flames so it gives you enough time to get out of that fireball wow it's a very scary statement actually getting out of a fireball in time yeah it feels like something from a magic it represented i know i guess if you understand the materials chemistry well enough that's what it's like right so yeah that nomex suit that he was wearing it's made from something that's called a meta aramid that sounds like something
out of the future not something developed in the 1960s it's essentially a semi-crystalline fiber and the chemical structure of it is uh rings of carbon atoms which are essentially benzene which is highly flammable so i find it a little bit weird in a way that it contributes to a flame resistant suit but i guess if you connect those benzene rings together it changes the ignition temperature and linking those benzene rings are some carbon oxygen nitrogen hydrogen groups which
chemists will know as amide bonds so that particular chemical structure means that it doesn't ignite in normal air and it also stops burning as soon as you remove the heat which suggests that there isn't a self-sustaining chemical reaction in that particular material and that's what the dupont website says it's fire resistant because of the chemical structure that sounds like something from star wars movie that someone would wear not to burn in the atmosphere
or something yeah it's it's very yeah space aged and not continuing to burn once it's removed from a heat source meant that well i assumed that even if it had caught fire in while he was in that like wall of heat as soon as he managed to walk out that heat source is removed and so it would stop burning and i guess that contributed to him having such minor injuries considering the scale of the incident yeah the fibers transfer heat really slowly and the weave is quite thick so that would
also help protect his skin and give him enough time to get out without getting too badly burnt yeah i think the report said that he had burns on just his hands and feet um and i know that the gloves um i think i read something that was saying something about they're updating the regulations and it was still coming through a new technology would be put into the gloves that would give them a better heat transfer index so it would protect his hands for longer oh if they'd had the newer
regulations he may not have even had any burns on his hands with the new heat transfer index regulations so it seems that formula one has their own regulations that they stick to within their industry that their equipment has to meet so going back to buildings is there something similar in terms of heat transfer index regulations there is quite a lot of details on uh regulations especially in the uk so there's like two approved documents so approved document a is to do with the
structure and how to build it the safety of that the loading and so on there's a proof document b which is all about fire safety and fire resistant because we can't really make it fireproof would be very expensive for a building to be a fireproof so it would be a regulations and requirement that you must have in your building so would which make your uh building resist fire for a certain amount of time so it would be an hour two hours and so on and the more hours you add the more money
you would add to the project so if you want your building to be safe for three hours would be much more expensive than if you want your building to be safe for one hour and so on it's all detailed depending on what you're doing and what kind of construction it is in the approved documents it's making me think do you have any examples in your own life where you can do things that you wouldn't expect you'd be able to do because of properties of materials i remember in chemistry
labs in school we had bunsen burners on the desks i don't know if they use them now are they gone to hot plates because i presume hot plates are safer i would wave my hand through the flame on in the bunsen burner i think that's worse than the eating matches but what i'd read was this like a layer of air around your hands that protects you it provides that insulation so you can wave your hand through fast enough and not get burned do not try this at home is that similar to putting
off a candle i think so i think well you meant to wet your fingers when you do the candle aren't you yeah and you can definitely feel your fingers getting hotter if you do it with dry fingers and you have to do it fast right if you do it too slow then you do burn yourself so is it the air that put off the fire not your finger what when you pinch a candle yes well yeah it's the fact that you stop the oxygen getting to the the flame right that puts it out but i think having the water
the layer of water on your fingers provides you with some insulation whilst you do the pinching because obviously that wick is still going to be hot you have to go with with confidence confidence in science yeah that's what it was oh gosh we were terrible children so i have a story of when i i was a kid so i was in pakistan in the kitchen and the gas is a bit temperamental sometimes so i turned it up really high on the cooker because the flow was very very low and i had like a
towel behind the cooker and suddenly the gas came back and it was really strong and it was on high and so the flame just um maybe it's called the traveling fire as i've learned today it traveled onto the towel and the towel caught on fire and me being like absolute disaster in panic situations i just picked up the towel and just stood there like holding like this flaming towel i don't know why i was doing this i just stood there like holding it a minute he's just like looking at me like
what are you doing and just grabbed the towel from me and just stood on it so again i think it's the same principle of like starving it of oxygen so stamping on it works as well rather than just the water and things like that so if you need to put a flaming tea towel out standing on it it works holding it doesn't work waving it around through the air to give it more oxygen yeah yeah it's a flag a flag a flag of fire like a fire that's what i was going for so obviously
there's several very like flammable materials and i wondered does anyone have any other examples of how you could fire proof so how could i have fireproofed that tea towel so that it wouldn't catch fire when the when the gas kind of jumped in the supply in my undergraduate days but i did a lot of work with theater and the old theater we were in it was it was quite historic and there was a lot of wooden structures in there we were told that the theater curtain that comes down
across the stage you can hold a blowtorch to it for 15 minutes and it will not set on fire what yeah which is quite impressive i think that's to give enough time for if there is a fire on stage obviously you've got a lot of wood and you've got some really hot lights it gives the audience enough time to evacuate which i guess ties into building regulations to some extent because you've got evacuation times to consider but i was also on a committee that organized an end-of-year ball
and we had a lot of fabricious decorations and we had to spray it in a compound that would make it fire resistant which apparently is quite a standard thing that any wall decoration has to be able to withstand fire when i looked into this some of this stuff we were using it was some sort like nitrogen-based compound with an aqueous polymeric binder which sounds less futuristic than the formula one racing suits i think there was something about when you apply heat to that the
nitrogen is released from this aqueous binder and nitrogen starves the oxygen getting to the material so it stops it from catching fire for a while at least until the nitrogen is exhausted and i also read that there are some fire proofing compounds that are sort of boron based and also contain a lot of water and apparently in an endothermic reactions that's when the chemical absorbs heat it releases water the rest of the compound then melts and coats whatever
fibers you have in this boron which of course if you're coating something with something again stops the oxygen from getting to it that prevents the oxidation there are quite a few things out there that can make something that is flammable less flammable for long enough that you can get out of danger that's really cool i didn't know that they could spray things to make them less flammable but it kind of suggests that there's more to consider
than just the type of material that we're using for a way that given your background in civil engineering what else needs to be considered so as laura mentioned you need a time to evacuate people one other aspect is introduced now to the fire safety engineering which is human behavior because we need to understand how the human behave in fire so like in your case anika you hold the towel and the other person who came in put the towel on the ground and stand off it so that's an example
of two different human behaviors so in order to design the building to be safe and get the evacuation exit in the right positions we need to understand how people behave and the other thing we would need to understand is how the smoke travels because the smoke is sneakier than the fire and even caused more death because you will die from healing the smoke because there's no oxygen anymore because the fire ate that up so we need to make sure that ventilation is right so
the smoke won't be stuck in the building in a case of a fire so there's lots of other aspect that we would need to consider regardless of the material is resisting fire and so on is how to get out of the building is a totally different story depending on the human behavior on fire as well yeah if you don't have a way to get out then all the other things are a bit useless and i think some of my learned safety behavior it comes not just from courses but from you know watching
things on tv there are lots of tv programs that will have a fire into some sort of disaster and you're meant to get down on the floor aren't you and you see people doing this in the program and get down on the floor and get away from where the smoke is unless you're vin diesel and then you can walk through the fire without any injuries because he's fire proof what's been diesel made of but he's made of diesel but according to fast and furious he can walk through flames and make out
alive you need to be made out of what that's similar to the banzing thing that he used to do the suit isn't it yeah maybe he sprayed himself in one of those fire resistant compounds it sounds like that's a good place to leave it because i could just start talking about fast and furious i think we should draw the conversation to a close it seems there's a lot of science and engineering that goes into making us safe we've discussed some of the chemistry behind flammable
materials and fire retardants and we also heard about how regulations are constantly evolving to continue to improve safety we don't see or experience most of these things and it's all come about because of research development and historical events find us on twitter at technically spur 11 what a catchy twitter name guys technically sp11 just you know just so you remember that one if you want to carry on this conversation or leave us a review and we'll
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