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Flammable Caps, and Hydrogen Sparkgaps.
>Yes, it did smell, Jim. It smelled just like auto oil, though not as
>thick. When I examined the label closer, it said "highly flammable-do
>not expose to fire or flame". Hmmmm. Is a cap exposed to flames?! Since
>I wasn't into pipe bomb capacitors, I called the retailer and he had
>just gotten shipment of pure mineral oil in. I was able to exchange it
>straight across, I filled my new caps, and am slowly breaking them in
>today.
>
>Thanks to everyone for the responses!
>Bob V
Bob,
Just a quick point: All fuels require oxygen to burn. In a 21% oxygen
atmosphere a typical higly flammable fuel such as petrol will only
burn if the fuel / air ratio is above 1/8 and below 1/20 (or so). What
this means is that if your cap container had the capacity of one
litre, you'd need about 60cc of petrol vapour to cause a fast
combustion (petrol burns the fastest at 1/16). At that ratio the
combustion would not be explosive (it never is in air with normal
hydrocarbon fuels) and you should expect less than 100PSI to be
developed.
Now, besides the fact that your pipe will most probably stand
100PSI+, and the fact that 100PSI explosions are not particularly
nasty (not supersonic), there is the fact that your cap is FULL of
oil, and there is therefore no room for air and possible combustion.
Add to it the fact that any air gap would be saturated with vapour,
and that oil vaporises extremely slow, and that sparks under oil are
not able to ignite anything (no air where the spark develops) and you
can be 101% sure that your cap will NOT explode. Now, if it was to
overpressurise and burst, that would be another matter (It could start
a fire). That is why some people use Kerosine on their caps.
Hope this is not too off-topic. I just hate hearing some popular
beliefs, such as if you use an aerosol spray can as a flamethrower the
flame will go back inside and cause it to explode, etc...
Sam Barros.
P.S. Good thing this safety stuff came up. I was looking at some
chemical data sheets and look at what I found (you probably already
know this):
Hydrogen has 5 times more thermal heat capacity than air at the same
temperature and pressure.
Hydrogen is several times more effective than air in carrying heat
away by convection.
Hydrogen has almost 2 times the voltage breakdown value of air.
Hydrogen has the fastest ion decay of all gases, and is one of the
most difficult to ionise.
Metals do not oxidise in Hydrogen (duh).
Therefore, Hydrogen is the very best gas you could possibly have in a
sparkgap. It will heat up 5 times slower and get rid of the heat much
faster. It will be smaller, and quench extremely well. The pipes will
never oxidise either!
Now, we already know this because all high-performance spark gaps
(Marx banks, Trigatrons, etc…) are Hydrogen filled (sometimes at high
pressures to further increase heat capacity and breakdown voltage).
So, we should all agree that a Hydrogen gap would be THE way to go for
a TC.
Now, why don’t we use them? Well, it is difficult to make one. Now,
here is my idea (You’ll love it:-)
Ok. I am going to build a nice RQ gap, and close off both tops with
PVC caps. I’ll raise the copper tubes a bit of the PVC pipe to avoid
melting and I’ll fit 2 valves. Than, I’ll purge all the air from the
gap and run it on My TC. There will be no oxidising, and the
performance should be dramatically better.
Note: I considered the fact that the pipes might vaporise and the
vapour will lower the breakdown value of hydrogen before it deposits
back into the walls. Maybe a way to circulate the gas would be
necessary. That would greatly add to the difficulties of the system so
I’ll leave it for now.
Any ideas, comments?
==
Sam Barros,
sambarros-at-yahoo-dot-com
ICQ#:15156975
"The Less You Know, The Better You Sleep"...
"Evolution Stops When Stupidity Is No Longer Fatal"
"If At First You Don't Suceed, Increase The Amperage"
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