Forums > Technical Discussion > temperature of a burning wick?

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arashi
arashi

Pooh-Bah
Location: austin,tx
Member Since: 21st Mar 2002
Total posts: 2363
Posted:Like, for real though.

How hot does the flame from a _large_ poi wick soaked in kero or paraffin get? Does volume of fuel or surface size matter to the overall temperauture?
I'm only looking for general ranges, say within +_ 20 degrees here.

How about the same for Coleman's?

does anybody have a laser thermal reader? i'd also like to know how hot a piece of metal gets with continual immersion in the flames of both fuels, if it's different from the flame tip. obviously size would matter here as a function of burn time, but let's say maximum temperature possible.


-Such a price the gods exact for song: to become what we sing
-Seek freedom and become captive of your desires. Seek discipline and find your liberty.
-When the center of the storm does not move, you are in its path.

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mtbeer
mtbeer

ARRRR!
Location: Charlotte, NC, USA
Member Since: 11th Aug 2004
Total posts: 529
Posted:There was an old thread on this:
http://www.homeofpoi.com/ubbthreads/show...rev=#Post132073
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Not much in the way of concrete numbers. I would also be very interested to know the temps for different fuels.


"My skin is singed but it heals my heart and with glowing pride I'll wear my scars." -Davey Havok

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UCOF
UCOF

Carpal \'Tunnel

Member Since: 17th Apr 2002
Total posts: 15414
Posted:I dont think Coleman's fire poi are very much different to anyone elses wink

A question on that thread ...

hang on a minute...

should we just not post in that thread instead of carrying on with this one?

That is the whole point of searching for a thread....

smile


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arashi
arashi

Pooh-Bah
Location: austin,tx
Member Since: 21st Mar 2002
Total posts: 2363
Posted:well thanks for the link but even with all the big wig fire boys nobody knows. is there not ONE fire spinner in the world who's also a mechanic and has a thermal laser?

-Such a price the gods exact for song: to become what we sing
-Seek freedom and become captive of your desires. Seek discipline and find your liberty.
-When the center of the storm does not move, you are in its path.

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ImmortalAngel
Scientist!
Location: Waterloo, Ontario, Canada
Member Since: 19th Jan 2004
Total posts: 578
Posted:Go to a university with an enginering campus, befriend people and get them into spinning, and pray the university has a thermal laser ^.^'
If you befriend the right people, it could mean more than just thermal lasers, it could have dozens of breakthroughs in all fire toys biggrin
It could revolutionize Poi as we know it!
Do you have it in you?


Educate your self in the Hazards of Fire Breathing <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> STAY SAFE! <img src="/ubbthreads/images/graemlins/hug.gif" alt="" />

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mtbeer
mtbeer

ARRRR!
Location: Charlotte, NC, USA
Member Since: 11th Aug 2004
Total posts: 529
Posted:That's a good idea. I have a few friends in the field\school that most likely have access to an IR thermometer. I have always wanted to be a mad scientist but I guess being the guinea pig would be cool too.

"My skin is singed but it heals my heart and with glowing pride I'll wear my scars." -Davey Havok

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marco
enthusiast
Location: uk
Member Since: 27th May 2004
Total posts: 328
Posted:
Firstly, non contact infra red thermometers or thermal lasers as you describe them, which the're not, the laser pointer is there for the operator to judge positioning etc, are not a reliable means of assesing lit wick temps, since I'm sure your aware that a large proportion of the spectral output for fire poi is in the infra red region, anywaty the temps encoutnered in fire vary significantly, due mainly to oxygen flowrates and design, stationary poi tend to run at a substantially lower tempreture than rotation poi, faster the rotation, the more fuel and oxygen is burnt, during this mode of operation the surface sick temp will tend to be much higher, it would be kind of amusing to try following poi ratation at several revolutions per sec with a hand held thermal non contact device, I'll leave you to work out the mechanics of that one,

To answer you question though, kero poi tend to burn around 600 to 700 degrees cel, flame temp, the kevlar wick surface 'tends' to be much lower than this, however this rises with burning time, since fibre glass obsorbes some of the generated heat, obviously, typically though after an interupted burn the poi head can be handled without burns, provided the exposed metal parts are kept away from, intially surface temp counts are to be expected around around the 65 deg mark, although this rises as the surface and interior material take on some of the heat generated, i've enncountered surfave temps pf around 150 deg, plus, although this drops fairly quickly.

exposed metal work however being typically a very good conductor compared to the wick, runs very much hotter, poorly built poi head i've seen getting chery red, after repeated burnings, a good heavy build however will easily reach temps of around 800 degrees after repeated burnings, although dipping in fuel will act as a coolant,

For contact and burning times though, you can reliably bounce a lit poi head off skin, for arm wraps and things, however any exposed metal work will cause second degree to third degree burns on contact,

As for colmans aka refined petrol you shouldn't even be considering this for poi application, check out the safety info on this site regarding fuels, as for fire poi temps, i wouldn't know since i don't use the stuff for anything else than fakir, a very different art.

To sum up then,

non contact infra red thermometers not a reliable way to assess temps

wick size and fuel loads and saturations will affect temps

speed of spinning will afffect temps

wick surface temp will be very different from flame temp

wick temp increases with buring time however flame temp will remain fairly constant

metalwork will be much higher in temp

probably not possible or certainly not practical to assess accurately within the temp ranges your asking,

you will need a thermal pile to check temps, for checks when spinning you will need to wire wrap the probe to the wick surface, affix safely and securely the cable from the probe to the chain, strap or tape securely the recording instrument to the arm, or if you have a long enough cable suggest pocket,

i might have a play witt this over the weekend,


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mtbeer
mtbeer

ARRRR!
Location: Charlotte, NC, USA
Member Since: 11th Aug 2004
Total posts: 529
Posted:I still need to do a comprehensive controlled set of tests but here are some basic observations from last night. All measurements are in degrees Fahrenheit taken by an IR thermometer off the wick (not the flame) at close range.

The size of the wick seems to have very little effect on the temperature however the burn time does. Large wicks with greater fuel capacity generally burn longer and achieve higher temperatures. As an example, a 4" staff wick quickly rose to 300+ degrees after ignition, then gradually climbed to 412 degrees by the middle of the burn and finally ended at 502 degrees.

Another major factor is the initial temperature of the wick before you light it. Cold wicks take a few minutes to heat up and may not get hot enough to produce a large flame. Warm wicks will light up faster, burn brighter and end with the highest temperatures. There was about a 30 degree difference in final wick temperature between a cold and warm start.

I don't have any solid numbers on how the speed of your spin effects the temperature. At first glance it appears to be another major factor in the final wick temperature. After a moderately paced poi spin with kerosene, the final wick temperature only rose to around 300 degrees.

I only tested three fuel types: Kerosene, Ethanol\Boric Acid and Ethanol\Copper Chloride. Both ethanols ended up about 15 to 20 degrees hotter than the kerosene but also had much shorter burn time which implies a much hotter fuel.

Depending on the combination of variables here you can expect wick temperatures in the range of 300 to 650 degrees. Keep in mind that most Kevlar blends will melt\burn at just over 700 degrees so a warm wick combined with a hot fuel will quickly degrade your kevlar.

Here are some variables that need further testing:
Air temperature
Humidity
Altitude
combination fuels (white gas, lamp oil... etc.)
speed of the spin
temperature of metal parts


"My skin is singed but it heals my heart and with glowing pride I'll wear my scars." -Davey Havok

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arashi
arashi

Pooh-Bah
Location: austin,tx
Member Since: 21st Mar 2002
Total posts: 2363
Posted:Thank you so much for your intelligent and useful responses!
As I suspected, it seems that spinning a wick will decrease the temperature of the wicking due to air cooling the surface.
I believe the reason the tempreature increases with burn time is due to the wicking properties of the kevlar changing with it's temp. With an increase in temp, wicking happens faster because the fuel is in a higher state of vaporization at the barrier.

sometimes folks like to burn with straight coleman's due to the lower burnoff toxins, which is why i was interested in the temps for it as well.. i believe it would be at least 20-30 degrees hotter. Mixes, well, i'm less interested in them as they vary for each toy. knowing each ingredient's temps is enough, no?
as for the temp of the metal... i considered this to be closely indicative of the actual temperature, so it seems if you took a wick and burned it repeatedly while holding a piece of metal in various areas eventually it would achieve the highest temperature for that region of flame, giving you a complete topograpghy of the temp zones. It would be even easier and quicker with copper or something that conducted better.
I believe air temp would mostly effect the wicking effects of the kevlar by abovementioned air cooling rates. seems like the variables for air temp and kevlar temp would go up and down together. but once ignited, chemically the fuel will want to burn the same amount of air given the same air pressures. so air temp would basically only affect rate of vaporization, right?


-Such a price the gods exact for song: to become what we sing
-Seek freedom and become captive of your desires. Seek discipline and find your liberty.
-When the center of the storm does not move, you are in its path.

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Gri-gri
Gri-gri

Member
Location: Richardsbay, South Africa
Member Since: 14th Dec 2004
Total posts: 84
Posted:Okay, you guys are way too bright for me, but I'm going to put in my couple of cents regardless of how misdirected I may be...

From what I can gather, in relation so the speed at which the poi are spun and the temps reached. I would assume that there will be an optimal level at which the wick burns hottest.

As the poi spin faster there is more oxygen available for it to burn, however, as mentioned there would also be a gradually increasing cooling affect from the very air that's helping it burn.
So I believe that what you'd find is that the poi would be at there hottest at a speed where the most oxygen is made available for the wicks to burn, but not so fast that the atmosphere begins cooling it down again. And of course this speed will vary according to the temp of the air around you.

Having said all that, I have absolutely no qualifications to back any of this up, I just know, when I do a wrap and it goes wrong, it's *&%$@!!# HOT!!!!


Where the mind goes,
The body will follow...

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arashi
arashi

Pooh-Bah
Location: austin,tx
Member Since: 21st Mar 2002
Total posts: 2363
Posted:you know, i suppose i'm interested in the temperature of the flame itself as well and not just the wick.
i found a buddy who has an IR thermometer i might be able to borrow. so now i was trying to design experiments. my aim is to measure the heat given off of the flames from various wicks due to various fuels.

i was thinking of immersing several pieces of copper wire in various areas of the flame, from the sides of the wick to the flame tip. At various times, and multiple burns, take the temperatures of the wires. If i'm not as dumb as i look, the temp. of the copper should reflect the hottest temp achieved.
i will use a small fan to measure the effects of various speeds of spinning.
1. should i use a metal with lower conductivity like steel? the conductivity would only affect the rate of heat absorption, right?

i'm going to do staff wicks, eating wicks, poi wicks, several fuels.

anybody else wanna replicate and compare notes or help me redesign a better experiment?


-Such a price the gods exact for song: to become what we sing
-Seek freedom and become captive of your desires. Seek discipline and find your liberty.
-When the center of the storm does not move, you are in its path.

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mtbeer
mtbeer

ARRRR!
Location: Charlotte, NC, USA
Member Since: 11th Aug 2004
Total posts: 529
Posted:Most IR thermometers have a pretty wide field of view that they read from. Something like +/- 8 degrees. They take the average temperature within that field of view so a copper wire would most likely be too thin to get a reading from. Obviously the chaotic nature of flame would also make it very challenging to get a consistent reading. Taking the temperature of a wick is pretty easy as long as you get close enough to keep the entire field of view over the wick.

You might want to try some type of immersion thermometer where a metal probe does the reading. The trick is to find one that can handle temperatures of 800-1000 degrees F. I have seen a few that go up to 650 degrees F. Again, you will still have the problem of a chaotic flame and the temperature will only reflect an average over a period of time.


"My skin is singed but it heals my heart and with glowing pride I'll wear my scars." -Davey Havok

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Nucleopoi
Nucleopoi

chemical attraction
Location: Ilkeston, Derbyshire, England
Member Since: 6th Nov 2004
Total posts: 1097
Posted:i think we can say that wicks get very hot and hurt when they hit you...

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Nate
Nate

Groovy ga watashi no namae desu!
Location: Oxford, Oxfordshire, England
Member Since: 5th Aug 2004
Total posts: 1530
Posted:i aggree with nucleopoi.......'nuf said



however i did enjoy reading your findings guys, and look forward to more.......an interesting scientific experiment....it cant be ubblol


I like Languages.

Educate your self in the Hazards of Fire Breathing STAY SAFE! <img src="/ubbthreads/images/graemlins/hug.gif" alt="" />

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vanize
vanize

Carpal \'Tunnel
Location: Austin, Texas
Member Since: 21st Aug 2001
Total posts: 3899
Posted:ro answer the original question - a fire with the same fuel has the same temperature regarless of size - it just radiates a lot more heat when it is big - twice as big puts off roughly 4 times as much heat (ballpark guess - it will e exponential, but not sure if the expnent is exactly "2" in this case), but the core temperature of the flame is still the same.

-v-

Wiederstand ist Zwecklos!

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