Re: Tesla Coil Firehazards (Exploding paint cans) (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sun, 12 Aug 2007 07:29:35 -0700
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>, tesla@xxxxxxxxxx
Subject: Re: Tesla Coil Firehazards (Exploding paint cans) (fwd)

At 05:49 AM 8/12/2007, Tesla list wrote:

>---------- Forwarded message ----------
>Date: Sat, 11 Aug 2007 20:48:50 -0700
>From: Nathan Stokely <50kva.54uf.750a@xxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: Tesla Coil Firehazards (Exploding paint cans) (fwd)
>
>Well, I assume that the streamer went to the seam on the can. This is
>because the seam has no paint thus making it slightly more conductive than
>the rest of the can. When I have had this happen, I have not been paying
>close enough attention to know exactly how it happened. Because of the
>nature in which I use my coil, it is totally possible that the streamers
>were striking the can for an extended period of time. If anyone knows the
>exact temperature of the average streamer, please let me know.

It's not a temperature of the streamer thing, it's a energy carried 
in the streamer, which would then be transferred to the can, heating 
it up.  I would be somewhat suprised if a streamer carried more than 
5% of the coil's input power to whatever it hits. Not only is there a 
fair amount of input energy dissipated in the spark gap and the 
series resistance of the secondary, but there are probably many 
smaller streamers dissipating some power, and, of course, you have to 
keep the streamer hitting the can hot enough to be ionized, which 
takes a fair amount of energy.


That said, if one had a small NST powered coil with, say, 450 W 
feeding it (the usual 15kV 30mA), and you got, say, 20 Watts into the 
target, and the target was a low melting alloy solder, it might 
melt.  Think of using a soldering iron.  Pretty iffy, though... 
you've got that big can sitting there as a heat sink.  Heating the 
valve might be more productive as a means of destruction: low thermal 
conductivity, low melting point.


>I am not
>always watching my coil when it is in operation. I suppose it would be a
>good idea to have a highspeed cam watching the coil and put a paint can in
>the streamers for an extended period of time to see exactly what happens.
>However, I am not going to try this. I will let somebody else (like a
>pyotechnician) replicate this.


An easier test... get a cheap soldering iron in the tens of watts 
range, rig up a jig to hold it in contact with the can.




>On 8/11/07, Tesla list <tesla@xxxxxxxxxx> wrote:
> >
> >
> > ---------- Forwarded message ----------
> > Date: Sat, 11 Aug 2007 16:19:43 -0700 (PDT)
> > From: Yurtle Turtle <yurtle_t@xxxxxxxxx>
> > To: Tesla list <tesla@xxxxxxxxxx>
> > Subject: Re: Tesla Coil Firehazards (Exploding paint cans) (fwd)
> >
> > As someone who has placed a fair number of aerosol
> > cans in fires, I'm dubious. Placed in the middle of a
> > hot fire, a can takes "a while" to blow up. And I'm
> > talking about a fire with HOT coals.
> >
> > However...
> >
> > The can's Achilles heel is the valve. It's possible
> > that the valve could have failed, causing the flamable
> > spray to be released, then ignited. A quick Google of
> > "WD 40 flame thrower" or "WD 40 burn" will turn up
> > lotsa hits.
> >
> > However, the odds of a strike causing a valve to fail
> > on more than one can seems a little high. There's no
> > way a coil can heat the contents enough to boil.
> >
> > Again, I'm dubious, but not quite ready to call him an
> > outright liar.
> >
> > Adam
> >
> > --- Tesla list <tesla@xxxxxxxxxx> wrote:
> >
> > >
> > > ---------- Forwarded message ----------
> > > Date: Sat, 11 Aug 2007 09:32:22 +0800
> > > From: Peter Terren <pterren@xxxxxxxxxxxx>
> > > To: Tesla list <tesla@xxxxxxxxxx>
> > > Subject: Re: Tesla Coil Firehazards (Exploding paint
> > > cans)
> > >
> > > I'll call your bluff on this one and say that you
> > > made this one up.
> > > You say you have encountered explosions with paint
> > > "most often".
> > > Two reasons I find it hard to believe you.
> > > A can is almost a full Faraday cage and it is hard
> > > to imagine how a strike
> > > could give a spark inside a can.  The contents are
> > > probably not flammable
> > > themselves (hydrocarbon propellant and paint) until
> > > mixed with air.
> > > Striking the outside of a can results in very little
> > > heat transfer. Try
> > > heating a full coke can and you will be very
> > > disappointed.
> > > So as you started this, please give details of :
> > > 1 Exactly how many explosions you have had?
> > > 2 What were your TC details including power?
> > > 3 Was it just streamers that ignited the cans as you
> > > say, not direct sparks?
> > > 4 Did the cans have caps on them?
> > > 5 Why didn't you stop having the TC strike the cans
> > > after the first flash
> > > fire?
> > > 6  If no-one on this list can reproduce your
> > > findings and we believe that
> > > you have lied, what should the group response be?
> > >
> > > Peter
> > > http://tesladownunder.com
> > >
> >
> >
> >
> >
> > 
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