Is Fire Conductive?

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bphgravity

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I recently completed building a nice little 9,000 volt, 30 mA Jacob's Ladder. I have been performing a few experiments by seeing what the resulting arc can catch on fire. Basically, I have been suspending items between the copper tube electrodes to see what happens when the arc comes in contact with the material.

I have noticed when an item combusts into flames, the flame instantly spreads between each electrode and allows the arc to continue. I have managed on two occasions to remove the material that has caught on fire, and the flame stays with the arc. As soon as the arc is suppressed by the distance between electrodes, the flame goes out.

This is quite weird to see. It really appears as if the flame itself is acting as a medium for the arc to conduct through. Is this possible? I have tried a few internet searchs and have not found any sites or documents that discusses this phenomenon. Anyone know of any studies on this?
 
Re: Is Fire Conductive?

What about the gas from the burning material? May not be the flame itself, but mighty close to it.

Very interesting. Do certain materials produce the stable arc better than others?

Jim
 
Re: Is Fire Conductive?

I believe flame is conductive. I think some furnaces use this technique to detect the presence of a flame according to a topic posted a few months ago.

Makes sense too. The flame must contain many ions which are conductive.

Rattus
 
Re: Is Fire Conductive?

Sounds like ionization around the electrodes, if I'm understanding what you're doing. That's a factor in arc blasts. :eek:
 
Re: Is Fire Conductive?

AHH, That's right! Carbon-Arc Lamps. Two electrodes with carbon tips. The arc creates great heat in the carbon which then becomes incandescent. As the arc rises and the electrodes separate, carbon vapor must be present allowing current to continue to flow. Neat.

Thanks Wayne!
 
Re: Is Fire Conductive?

Very good Bryan. :D


sperry00.jpg


Carbon Arc Searchlight Facts:

The first 60 inch Searchlight was made by General Electric in 1893
Searchlights were produced for military use from 1932 to 1944 at a cost of $60,000 each!
Lamp Type: Carbon Arc (no light bulb!)
Candle Power: 800 Million
Effective Beam width: 5' plus
Effective Beam length: 5.6 miles
Effective Beam visibility: 28~35 miles

GENERATOR:
Generator Power: 15 KWV nominal - 16.7 KWV max. (15,000~16,700 watts D.C.)
Powered By: Inline 6 cyl. "Hercules" Flathead Engine
Generator Engine Fuel: Gasoline (can also be run using Kerosene or Gasohol)
Combined Weight: 6,000 pounds (3 tons, or the weight of 3 Ford Mustangs combined!)

The beam is made by 2 carbon rods, one positive and one negative, arching within the focal point of a 60 inch parabolic mirror. As the rods "burn" they are automatically fed into the light. The rods last approximately 2 hours and are then replaced. The flame that is visible during the lights operation, is not actually the source of the light, rather, it is a by-product, produced as a result of the electricity arcing between the 2 rods. The flame is the rod slowly burning away as it is fed into the light. The arc draws 150 amps continuously at 78 volts and burns at over 3,000 degrees Fahrenheit. The power is supplied by the D.C. generator which was designed specifically for this purpose.
Click to expand...
CULAKE1.gif
 
Re: Is Fire Conductive?

Carbon arc search lights are very cool. 800 million, wow.

Bryan, congradulations on the success of your project. I'd be interested in photos or shematics. Like I said in another thread, mine didn't work to good. :(

The flame is very interesting. I'll have to think about this some.

If my understanding is correct, the light produced by a flame comes from the energy that's contained in a molecular bond being released when it's seperated into two molecules and or atoms. At certain energies a photon shows up.

This is really conjecture on my part but I'm thinking that what happens with your gadget is that gases and or suspended particles are in the arc and some or all of them are ions and or molecules that aren't electrically neutral and so they respond to electric and magnetic fields. The arc may just be capturing non-neutral stuff.

And different elements emit different frequencies when they spit out photons. I think that by putting different materials in the arc you get different colors and that makes it look more like a flame than an arc.

It sounds like fun Bryan. :cool:

Edit: I left something out.

[ June 05, 2005, 03:50 PM: Message edited by: physis ]
 
Re: Is Fire Conductive?

Don't know about fire, but one time in a Navy engine room we had a steam leak and were getting shocked. We had sparky come down (I was a mechanic) and check the leak with a voltmeter. One lead in the steam on on the pipe and there was voltage. It was static, but sure got your attention. We used to check for steam leaks with a broom stick. the high pressure superheated steam was invisible but it would cut the broomsitck in half.
 
Re: Is Fire Conductive?

From what I can find at least part of some flames are plasma. There seems to be some disagreement but I'm pretty well convinced that flames have at least a signifigant plasma component.

If that is true, then, yes, flames are conductive. And not just a little either.

This big table is a pretty good description of the characteristics of plasma. It comes from this page. Also click on "flames" there and the subject "science of fire" on that page is useful. It's pretty concise, you don't have to read a lot.

Plasma_Characteristics_Table.jpg


It's an interesting subject. I've never really gotten around to looking at it much. I'm glad you brought it up.

Here's a candle flame on a space shuttle (I presume) in microgravity.
candle_microgravity.jpg

I wouldn't have guessed that.
 
Re: Is Fire Conductive?

You are darned right flames are conductive. Hot gasses expanding from an arc are condutive too. We had a situation where we were doing UL destructive testing inside some equipment. THe test was to create a short, stand back, and flip on the power. To pass the test, nothing inside could short to the case. There was all kinds of mayhem inside the unit when we did this (that was planned) but we kept getting shorts to the case, through a plastic barrier! :eek: Turns out, the hot expanding gasses that exploded out of things that were shorted out, would fill the interior, eventually find a crack or a pinhole, and then the case is shorted to live wires through a conductive gas. All this happened in milliseconds time, once the main fuse blows the fun is over. While not exactly a "flame", this illustrates how arcs can spread from an original phase-to phase short to a three phase bolted fault in a matter of milliseconds. The hot gasses in a flame should work very similarly.
 
Re: Is Fire Conductive?

That's a very interesting thought. It's never occured to me before that when something blows up the gases around conductors can short those conductors.

I don't think I've ever seen it considered.

I'm having a hard time imagining that sticking an extension cord in a flame could pop the breaker without the wires touching though.

Hmm.

Edit: Error A

[ June 06, 2005, 05:40 PM: Message edited by: physis ]
 
Re: Is Fire Conductive?

Many, many years ago, there was an article in POPULAR ELECTRONCS that led me to using conductive flame as a lo-fi speaker. By adding different ions to the flame through a wick, we actually got a few squeeky sounds out of a bunsen burner.

The electrodes inserted into the flame had a high voltage DC bias, onto which was impressed an audio signal.Dang thing actually worked.

The line in the article I really enjoyed was,
"Let's stick a couple of electrodes ino an oil well fire and see if we can WOOF Texas off the map!

Flame really conducts well.
 
Re: Is Fire Conductive?

Wow. I've always been interseted in new ways to deal with guitar signals using "natural" methods.

Guitar signals and transitors and digital processing all fall short. At least so far.

Putting a signal through a flame could be very interesting.

Edit: It's at least similar to tubes. not exactly the same though.

Edit: Maybe it is the same.

[ June 06, 2005, 11:14 PM: Message edited by: physis ]
 
Re: Is Fire Conductive?

I'm not sure what to make of all this.

First of all: plasma's??? I've heard the term before (and I caught part of the discussion between Physis and Iwire about the plasma in a MH lamp in a magnetic field), but I don't really know what a "plasma" is.

Physis: your source said a gas has very low conductivity, but that depends on the type of gas. Any gas with ions in it will conduct since the ions are free to move and are charged. (Maybe a plasma is just an ionized gas????)

STeve
 
Re: Is Fire Conductive?

Originally posted by steve66:
...but I don't really know what a "plasma" is... ...(Maybe a plasma is just an ionized gas????)
Click to expand...
Plasma is a state of matter. Many people only think of three states of matter; gases, liquids, and solids. In actuality, there are 6 forms of matter. Plasma is one of them. It is very similar to gas properties but at extremely high temperatures. And yes, it does have very conductive and magnetic properties as well.

Can anyone else name the other 2 forms of matter?
 
Re: Is Fire Conductive?

Fisson and thermonuclear ?? As a "wild guess" only interested in the subject and poking at a answer.
 
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