There's More to Fire Than Heat, Fuel and Oxygen (or, Fire Exists Within a Sphere of Changing and Interdependent Circumstances)

Fire is an interaction between Heat, Fuel and Oxygen completely dependent on proportions, conditions and physical relations. It is not a self controlling, self adjusting system created to serve us; no, that it is not. What fire really is, is a sometimes beautiful, sometimes terrifying expression of physical laws, chemistry and energy which can serve us without intention or harm us without malice. Fire is the product of a universe which we can understand functionally and work with; one which does not judge, reward or punish.

By Steven Edholm

Hey all you pyros!  I wrote this a while ago.  I was going to take some relevant pictures and make it more of a tutorial, but I think it stands pretty well on it's own and video might just be a better format to explore some of the details.  So here it is in all it's theoretical, abstracted glory.

We've all heard of the three things it takes to make a fire… HEAT, FUEL and OXYGEN.  While it’s true that these are essential elements of fire, it is also true that without a fourth and equally important requirement there is no fire! Understanding this fourth requirement is key to effectively starting, controlling, utilizing and maintaining fire.  It can be understood both logically, and intuitively through experience.  It is the underlying and unifying principal of fire and no more or less dependent on the other three elements than they are on each other.   And what is the secret ingredient?  Drum roll please:  The secret is simply the sphere of circumstances in which the heat fuel and oxygen exist, which allows the chain reaction to continue or vary in quality.  Put more simply, we have to put heat, air and fuel together effectively to make fire happen and continue.   And then, to expand a little further, how heat, fuel and oxygen are put together, the condition each is in, and the quantity of each affects the characteristics of the fire.  Simple?  Basically yes, but it is still something of a journey from that simple idea to effectively maintaining and managing fires for various uses.  When you factor in the many circumstances which contribute to or detract from this chain reaction and consider that we want different types of fires for different purposes it becomes less simple, but then so much more compelling!  Join me in exploring a few details of this sphere of circumstances, because it is the details, some of them minute, that make the difference in how (or even whether) a fire burns.

There is a model that is use to explain fire called the tetrahedron of fire.  It is a 3 dimensional pyramid with 3 sides and a bottom.  The three sides represent one each of heat, fuel and oxygen.  The bottom represents an uninhibited chain reaction, or the fourth element.  This fire model used to consist of only three parts, fuel, heat and oxygen, represented as a one dimensional triangle, but it was modified to represent the fact that fire does not exist without the proper relationship of the three tangible elements.  Thus, the tetrahedron roughly represents what I am trying to tell you, which again is that fire exists and varies within a sphere of changing and interdependent circumstances.  However, the tetrahedron model is so simple that it begs description and actually communicates nothing without additional information and explanation.  I suppose that the series of articles I hope to write, and of which this is the first, will partly be that explanation and information from a practical standpoint, and of use to laypeople like us.  I would like to see a fire model communicate some practical details, but my attempts to make a better model or diagram have been a fail.  I suppose that the simplicity of the tetrahedron model may sometimes be an asset as it does not describe any one of the many types of fire.  On the other hand the model is unable to communicate in any way the manner in which a fire functions and far too little about how it can be modified and controlled toward practical ends.  I find that the tetrahedron model has little practical use here beyond what I’ve already discussed.

HEAT, OXYGEN AND FUEL DOES NOT ALWAYS A FIRE MAKE:  When I was 20 something I was on top of maintaining fires at public gatherings and such.  Now I'm inclined to sit back and let some eager, enthusiastic youngster do the job…. but they often don’t, which kind of sucks.  I still often find myself raising my creaking, cold butt from the lukewarm side of some smokey waning fire to go fumble around in the dark for some firewood.  If I'm patient or stubborn enough to wait for someone else to get up to add wood to the fire or, often more importantly, make adjustments to the wood that is already in the fire, my patience is not often well rewarded.  Frequently, the poorly selected (… if selected isn't even just too strong a word to use lol) wood is added haphazardly or with an evident lack of understanding.  All too often the new wood is somewhat randomly thrown on often creating more problems than there were in the first place.  Kids today… sigh…  Adding more fuel to the fire or just blowing on it does not fix everything.  Fire is an interaction between Heat, Fuel and Oxygen completely dependent on proportions, conditions and physical relations.  It is not a self controlling, self adjusting system created to serve us; no, that it is not.  What fire really is, is a sometimes beautiful, sometimes terrifying expression of physical laws, chemistry and energy which can serve us without intention or harm us without malice.   Fire is the product of a universe which we can understand functionally and work with; one which does not judge, reward or punish.  Understanding a little fire theory can go a long way in enabling us to create, control and influence fire.

No, fire is not just Fuel, Heat and Oxygen, but in a very real way it is a product of specific relationships between those three elements which allows them to undergo the continuing chain reaction of combustion.  Lets look quickly at some varying conditions:

*If you have the heat of a match a foot away from some well sized and placed fuel, even with oxygen all around in the air, you do not have fire.

*let us say that you have a big round log being heated with a propane torch while surrounded by air.  Thats a lot of heat, and plenty of air, but in most circumstances the log on its own will not really flame a whole lot, it will more likely smolder and eventually go out after the heat is removed.  If we add another log or some smaller fuel, in the proper spatial relationship, our big round log will burn more quickly,  more thoroughly and longer, basically because of the interaction of the burning fuel units with each other.  They heat each other and bounce heat back and forth.

*If we have a healthy fire burning away and add a quantity of very green moisture laden wood, the fire will falter and slow down mostly due to the effect of the moisture on the factor of heat.

*Throw a bucket of water on the fire and so much heat will be removed as steam to heat the water that the fire is likely to go out completely.

*Cram the logs in a fire too close together or smother it with dirt and you will not have enough oxygen for a healthy blaze.

*Move the logs too far apart from each other and they will not contribute to a mutual build up of heat between them and are likely to smolder and each may eventually just stop flaming, begin to smolder and eventually just go out.

 All of the above examples illuminate the importance of specific relations between the three concrete elements of fire.

Fires have almost living characteristics.  Like a living body, fires that we use to our ends often need attention and feeding to achieve certain goals.  Maintaining and using fire effectively is all about details and the details that make a very functional fire can be very subtle and minute.  No one really taught me to use fire properly.  I learned by immersion.  The lifestyle I chose demanded that I understand combustion enough to maintain an acceptable level of functionality.  If I couldn't make a fire quickly with damp wood I wasn't going to finish cooking dinner before dark.  If I managed the fire poorly every night I was going to wake up with sore eyes and a woodsmoke hangover.  By the time Mors Kochanski introduced me to the tetrahedron of fire model I already understood it functionally, but had never put it all into place with symbology.  I ultimately can't teach anyone either.  Understanding fire functionally and not just theoretically is a personal journey.  I can maybe start the fire for someone, but their enthusiasm, action, intention and maybe most of all need to keep that fire going, are what will ultimately create a functional understanding.  Fire is fascinating to all people on some level, but most modern people do not find enough use for it to manifest a good working knowledge.   If you want to understand fire functionally and stay in practice, there is no better way than to place yourself in a position of need on a regular basis.  Start fires regularly, and start them from scratch never using paper or accelerants.

The simple but important information I've just presented above forms the foundation of a good working relationship with fire.  Whether you are starting, managing or putting out fires, you are ultimately balancing or working mostly with the following concepts:

FUELS

*Conditions (wet, rotten, dry, warm etc…)

*Structure (dense, pithy, liquid, gaseous, etc…) 

*Composition (Lignin content, chemistry, growth rate, environment, species etc…)

*Sizes

*Shapes

*Spatial distribution (relation of fuel units to each other and to heat source)

*Flamability

AIR

*Access or lack of

*Heat generated drafts

*Air temperature

*Air density

HEAT

*Temperature

*Radiation

*Proximity

*Reflection

*Blocking

*Placement of

I know that information is rather abstract, but you don't have to be a total dorkus like me and memorize it all or anything!  I'm just using the theory to plant seeds that can lead to a functional and intuitive understanding of fire, because that is really where it's at.  When there is an impetus to learn, and these basic ideas are presented in context, people's ability to manage a fire rises very rapidly, within minutes actually.  I've seen this happen over and over when playing fire chess with students and friends.  I hope to write more in this realm and put theory into context with either videos or more blog posts, so stay tuned.

One last thought, its easy to get cocky about ones understanding of fire.  The truth is though that the factors which contribute to a given fire burning or not burning are complicated and not always easy to predict.  However well we think we know it, fire can sometimes surprise us.  Considering the often horrific consequences of uncontrolled fire, it is best to follow the precautionary principal when it comes to safety, and err on the side of caution.

Have something to add?  Did I miss something important?  Leave a comment.

fire

Tetrahedron, Tetrashmeedron: Quest for the ultimate fire model

By Steven Edholm

"Ultimately, I think that where all of this analysis leads to is that..."

When I began writing the post,  There's More to Fire Than Heat, Fuel and Oxygen (or, Fire Exists Within a Sphere of Changing and Interdependent Circumstances),  I wanted a basic model to represent fire.  There is actually already a model commonly used to represent fire known as the tetrahedron of fire.  It consists of a tetrahedron of course, which is a pyramid with 3 sides and a bottom.  The three sides represent one each of HEAT, FUEL and OXYGEN.  The bottom of the pyramid represents the circumstances under which those three elements interact and is commonly referred to as a chain reaction.  The common explanation of the tetrahedron is that if you remove any one of the factors represented by the four sides, the fire ceases, which is true.  I have never felt comfortable with this common model, and indeed part of the impetus for writing that first article was to emphasize the importance, to my way of thinking, of the circumstances which allow, inhibit, and shape the character of, a fire; In other words, to draw what I feel is rightful attention to the bottom of the pyramid.  What I ended up writing instead, or before I got to my point, was the epic analysis that follows!  I decided that I better just cut it out and use it somewhere else.  Lucky you.

I have a number of problems with the basic tetrahedron of fire model, but I think that many of them are due to my perspective as someone who has used fire quite a lot and would like to communicate information about starting and maintaining wood fires to other people.  I feel that from this perspective the tetrahedron model  doesn't emphasize the factors associated with an uninhibited chain reaction… or, especially, the actual means of controlling those factors to manipulate a fire into doing what it is that we want it to do.  In fact, being on the bottom with no real name, I feel that the fourth side of the tetrahedron is actually de-emphasized in the tetrahedron, although, you could see it as the foundation I suppose.  What I would like to see, is a model that demonstrates to some degree, visually as well as with a suitable name, the physical reality of fire.  I guess I feel that the tetrahedron is so abstracted and theoretical that it is not of immediate practical use to most people.  What I probably want is a model that is functional for fire users.  This model would show the interaction of the 3 elements of fire and emphasize that it is the chain reaction itself that is really the most important factor.  Yes its true that if you remove one side of the tetrahedron the fire goes out, but what of the complex interactions between the four sides which can cause a fire to burn, smolder or grow exponentially.

Fire is not a phenomenon that exists in a black and white world of burning or not burning.  Of course it can be reduced to that level of understanding, but that perspective is of limited use.  Rather, fire exists in a spectrum from the smallest smoldering spark to an inferno or even an explosion.  Even when wood is heated below the point of combustion it undergoes destruction.  Upon close scrutiny, what we really see is a spectrum with a few discreet, sensational points of especial interest, and not an all or nothing sort of situation.  In other words, the limited on/off switch simplicity of the tetrahedron model limits its usefulness in a qualitative sense.  When asked “what kind of fire” the tetrahedron simply says one that burns, or does not burn.  The other three necessary elements exist all around, but putting them together in the proper circumstances for combustion is much more rare.  I baked a pie today.  There was heat in the oven, the kitchen is largely made of fuel, and air is everywhere, yet the fire stayed in the oven.  Even the pie, in close proximity with a fairly energy dense flammable crust was just baked and not burned.  Having heat, oxygen and fuel does not necessarily mean fire.

The tetrahedron model doesn't say much to me.  I would like to come up with a model that is more immediately accessible.  Also, I mean accessible to all people.  Something that will say more about the process and requirements of fire at a glance with less need for elaboration.  This may be an impossible task if all forms of fire are represented.  The tetrahedron is simple enough that it doesn't specify anything and therefore can include all types of fires.  A model that is more functional might limit the types of fires represented, but in the interest of communicating information that might be useful to those who use, or would like to use, fire.

My main complaints with the standard tetrahedron are as follows

The fourth side doesn't have a name that really works.  It is usually referred to as the chemical reaction or the uninhibited chain reaction.  I've racked my brain (and plied the thesaurus) and the most descriptive word I can come up with is circumstances not very immediately understandable maybe and not very sexy, but…  Perhaps it needs more than one word?  At least circumstances leaves room for attributes of various individual fires  Either way it still begs description which is un-ideal.  I think being on the bottom also contributes to the minimization of circumstances in the tetrahedron model, and that feels wrong because circumstance is really what fire is all about.  To my mind the concept of circumstances should be at the center of the discussion and of the model because the other three elements are exceedingly common and even throwing them together haphazardly will not always yield fire.

The tetrahedron model doesn't foster any kind of understanding of what our relationship with fire can be as users.  It exists more in a theoretical framework where extrapolations have to be made, or much more data added, to understand fire functionally.  In other words, its hard to look at it and recognize anything.  It doesn't foster an understanding by its nature and says almost nothing on its own.

There is not even a hint at quantity in the model.  If I add more air the chain reaction is intensified.  If I limit air the fire may be either put out or it may be minimized.  It will die out with X amount of air in one set of circumstances and not another, and the same can be said for heat as well.  The variability of fire or its reaction to partial removal or addition of one or more elements is not represented.

A much greater grasp of fire can be had by understanding the spatial distribution of fuels, which the model does not address.  This goes for both the distance between fuel units (also dependent on fuel size and qualities)  as well as the vertical and horizontal alignments.  This point is much more relevant to solid fuels.

The behavior of the elements of heat and air are also missing from the tetrahedron model.  Draft, and the build up of heat between the fuel units, are crucial factors in understanding the behavior and manipulation of fire.  It would also be nice if our model could hint at this behavior.

All of the above hint at the concept that reactions of fire are complex and interdependent.  Change one element in quantity or quality and the others change as well.  An ideal practical model would represent in some way the interdependence and interaction between the three elements.

Maybe this is all too much to ask from a fire model!  I guess I have to give the tetrahedron a couple of points here.  It is kind of neato that there is this geometric model where  A, H & F each touch both of the other two and the bottom touches all three.  But on second thought, the chain reaction (oops, I meant circumstances), being less concrete than the others should probably be set apart as different than the other three and of course you already know I'm not happy about it being placed at the bottom as I feel this minimizes its importance.  The problem I've run into in trying to improve the model though is that if you separate the three it becomes difficult or impossible to draw the connections between the other three.  That is a place where the tetrahedron works.

Another possible merit of the tetrahedron is that it’s simple enough to include all types of fires… but… its too damn simple.  It just doesn't say anything.  Without explanation it's just a pretty shape, and you can explain what it's capable of actually showing in a few seconds.

The challenge in creating a useful fire model or diagram is to make it say something, and to communicate important information easily without confusion.  Some information may have to be left in the dust, and that's fine.  I want a model that can foster as much understanding as possible while still being functional and accessible.  I've tried to work on such a model, but so far I'm not very happy with any of the results.  In fact, I haven't yet decided whether they are even an improvement at all.

Ideally the model would represent:

draft… the crucial fact that burning things and rising heat draw more air into the firesphere.

The focal areas of heat that build up between fuel bodies and how this interaction perpetuates a fire.

The effect of the relationship between fuel sizes and the distance between fuel units on combustion.

fire as a product of the interaction of the Heat, Fuel and Oxygen and the fact that this interaction is widely variable depending on the circumstances.

Ultimately, it would actually require many diagrams and much explanation to show the more practical everyday physical realities and concepts of fire, but it would be nice if one primary and more encompassing model showed something immediately useful other than “it takes these three things to make a fire”…. and then as an afterthought, “oh yeah, they have to be uninhibited”…. and “if you take one away it stops”.  What about "if you take some of this away it slows down but doesn't stop"?… or "if you add more it goes faster"?

The quest for a better fire model may be a lost cause, and for now, I've given up.  I think my main beef with the tetrahedron is subjective, and simply that it seems to infer less importance to the things that really matter in practical fire applications; the things that I’m always trying to communicate to people as very important to working understanding of fires, and which I can see that many people have a poor grasp of.  Ultimately, I think that where all of this analysis leads to is that an actual fire makes the best model!  Imagine that!  I mean it's interactive, three dimensional and fun!  Perhaps we can only learn so much with two dimensional models, and will never understand fire by surfing the internet.  With a fire in front of us, and a little nurturing by someone competent with fire, a rapid understanding of the circumstances of combustion is possible.  And I’ve seen this over and over again when playing fire chess.  Immersion is generally the best teacher.  Put ourselves in circumstances which require competence and competence is fostered.  Hey, stop surfing and start burning!

http://www.youtube.com/watch?v=3UmC6acEHk0

Fire Chess: A fire learning game

One night at Glass Buttes Oregon (or day, or something in between), I was sitting by a fire with Tamara, Margaret Mathewson and Jim Riggs.  I’m sure there were other people there too, but I remember those guys for sure.  The fire, and how it was or wasn’t being managed, was a common topic in those days.  All of us were inclined to be geeky about fire, and we all used it enough to have a strong working knowledge.  We were observant and critical when someone added wood or adjusted the fire.  As fire enthusiasts, that kind of geekery was our idea of fun, but it was also serious to us.  Like if you put a bunch of chefs together and they’d be eyeing each other cooking and saying like “dude, that’s too much anchovy” and stuff like that.  It was all good humored, but this wasn’t just “lets geek out and be funny and nerdy”, it’s what we did.  And if you do something a lot and are good at it, you care, you notice details and you develop opinions.  None of us wanted to sit around in the smoke, or be cold, so the fire should be done right.  It was the focus of camp life and not to be accepted in just any old state that it happened to be found in.  Fire does not tend itself all that well, and tending is a matter in which attention to detail yields great returns in results.  Inattention, on the other hand, generally leads to discomfort, annoyance, cold food, burnt food, tearing eyes, cold butts or moving of chairs closer and farther from the fire. So anyway, we were all sitting around flicking each other crap about where the wood should be put and how, and what about that smoking end there, or Jim with his “upward focus” and me with my parallel fuels, and fire chess was born.  Someone was probably like Ok, that’s fine I guess, but If you do it this way that smoking end is dealt with.  And someone else was like hey, it’s my turn, and eventually it coalesced into a set of simple rules.  Each person gets a turn in rounds to either add a piece of fuel, or make one adjustment.  After each move everyone else analyzes the move and makes comments.  We thought that was fun for a while and used to play it occasionally when nothing else was going on and we were sitting around the fire, which was fairly often.

What I noticed though was that when new people unversed in the ways of fire tending were around, they picked up a great deal of understanding extremely fast.  So Tamara and I started using fire chess in classes, and sure enough, people went from fire losers to fire cruisers in no time.  Most people haven’t grown up around open fires and don’t understand how to manage them to desired ends.  Further, it often seems that it barely occurs to them that management of the fire beyond tossing some wood on every once in a while is worthwhile at all!  That’s Ok, we all have to start somewhere and we are what we do. One of the first campfires I had to start on my own, I used an entire candle's worth of wax, dripping and relighting to get it to finally start burning.  I had damp wood to work with, and I just did not understand how the system worked.  It was somewhat sobering just how lame I was in that capacity, and I started paying attention.  I soon put myself in the position of needing fire everyday for cooking and various other things, so I was forced to perform, but it was a gradual process.  I believe that fire chess works to quickly foster an understanding of fire starting and management for two basic reasons.

The first reason is that there are frequent and specific opportunities created for comment and feedback.  Feedback from both instructor/mentors and from other participants is frequent, but it is tied directly to actual results and occurrences second by second.  Fire reacts quickly in many cases providing dramatic lessons in a short period of time.  The results, positive or negative are visual and often immediate.

The second reason, and maybe the most important, is that participants are invested in the results.  They are paying close attention because someone might screw up their move, or make the move they are planning.  If someone does something that works well it’s noticed and commented on, which drives the point home so it sticks.  When the players turn comes they can build on what has gone before and they want to do well in the eyes of the group.

A few tips for instructors

*Start with a short discussion about the four elements of fire- heat, air, fuel and the relations and interdependence of those 3 tangible elements.  The less tangible fourth element of fire, how heat, air and fuel are in relation to one another, is what fire use and management are all about, so drive that home.  Upcoming posts should deal with that subject in depth.

*next a short discussion asking “what makes a good fire?”  This opens the mind and leads inevitably to the conclusion that there is no one good fire and that fires are managed for different uses.  Sometimes we want just smoke and no flame, and sometimes we want no smoke at all, more heat, less heat, different shapes, etc...  You can still play the game as if you want no smoke and to be comfortably warm.  The understanding gained by playing for a clean fire is the most generally useful and can ultimately foster understanding of the management of other types of fires as well.

*It’s not “all good”.  Sometime in the 60’s or 70’s criticism became uncool, everyone was doing their best and everyone got an A for effort.  The good and relevant points which began as that message are largely lost and the residue we are left with is a dogma that can hamper achievement.  Be critical.  Don’t be mean, that’s not constructive and it’s not the point.  Critical and mean are not the same hat.  If you have opinions, let them out and encourage others to do so as well (and don't use upspeaking when you do it!).  Constructive discourse requires analysis of information, formation of ideas and opinions, and expression of those opinions, along with the open consideration of the opinions of others.  It can be argued that everyone is doing their best under the circumstances, but the circumstances can change and constructive criticism can be an important part of that evolution.  Don’t be stingy with praise either.  Positive reinforcement works.

*If you are the teacher and think you know what you’re doing, stand back a little and let people learn at a comfortable pace.  You might be surprised how little prompting  is required by you.  As long as basic goals are understood and held in common, progress can be rapid even with people totally unfamiliar with fire tending.

*Start small since fires grow fast when constantly fed.

*Sized and types of fuel are as important as placement and maintenance, so have a mix of fuel types and sizes.  Dense long burning woods, dense fast burning woods, light fast burning woods, woods that throw sparks, woods that don’t throw sparks, woods that tend to smolder, woods that make long lasting coals, some bark, some leaves, etc...  Fuel type is important and having all types of wood will open windows for education.

*Mix all the woods together in a pile.  Throw in some inappropriate wood.  Nothing toxic, but a few chunks of pitch wood, some very punky wood and some green wood could be instructive.  Very few novices will notice that wood is green, but the seasoned will usually notice at first heft.

*Don't allot much time for fire chess, because it doesn't take long, and the fire will just get too large pretty fast.

What started as a natural pass time among fire nerds, developed into an effective learning tool.  Fire chess, in spite of the name and the critical element of the game, is not very competitive.  Everyone has the same goal, so cooperation is more common than competition.  If anything the competition is with the self, to understand more and function better.  For people who teach long term classes in outdoor living, you’ll find that after just a game or two of fire chess, the campfires will be managed much better for the duration of your time together.    It is also a good item to throw in a one day class about fire. Lessons learned are not limited to tending fires, but lend an understanding of the function of fire generally, including the important skills of starting them and putting them out.