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Safety For Spark Gap Gasses Experiment (Hydrogen Information)

 Hi Jim,  The fun part would be as you are blowing the air out of 
>theglass chamber, there would be a point reached where the hydrogen / 
air
>ratio would be perfect for a powerful explosion.  At that point 
anything,
>espicially static electricity, could cause a very dangerous explosion.  
If
>this thing works and others reproduce it, I would feel better knowing 
there
>was no possibility of explosion.  -  Terry >>>>>

 I did some extensive research on Air/fuel ratio, power output and 
burning characteristics of various fuels. It was serious research...
 My results showed that Hydrogen will burn over an impressive range: 
from approximately 8 to 74% in air (petrol goes from 4 to 12%. It won't, 
however burn properly unless you have a fuel/air ratio of 1/8 (one part 
of Hydrogen in 8 of air) that's twice the optimum ratio for petrol. At 
that ratio it will combust very quickly and could cause an explosion. 
There is however, one thing nobody mentioned: Hydrogen is the least 
dense substance known to men. Because of its low density, Hydrogen 
doesn't put out a lot of power when ignited. In fact, you can burn it 
inside a closed container, such as a bottle, and the pressure increase 
won't be enough to explode it. I tried it with a 2 litres cola bottle 
and the pressure increase was only 50 PSI. The bottle sustained no 
thermal damage whatsoever and the pressure wasn't sufficient to explode 
it... If you use oxygen, however... Well, nevermind. Just don't use pure 
oxygen and you'll be safe.
 Note, however that rocket engines burn LIQUID hydrogen. When liquefied, 
Hydrogen will increase in density 600 times. The fuel/air ratio will 
also be divided by 600, so it will only burn with liquid oxygen. I was 
foolish enough to attempt mixing one drop of liquid butane with a drop 
of liquid oxygen. When I ignited the mixture, there was a bright flash 
of light and a loud bang. The test tube was blown to pieces and I cut 
myself with the flying glass. That's because the heat of the reaction 
made the mixture expand 600 times, and than combustion made it expand 
some more couple of thousand times, so it resulted in a powerful 
explosion.
 Anyway, if you put your sparkgap assembly in an airtight box, and 
reduce the pressure to allow for the expansion, there should be no 
problems. If air does leak in, and it does form the perfect fuel/air 
ratio (which is unlikely, since hydrogen will start burning slowly 
before that), and it does ignite, a strong container will stand the 
pressure while the exhaust gases exit trough the same leak the air came 
in. If the container is fragile, it will crack and the exhaust will come 
out of the cracks.
 I believe such experiments are perfectly safe, provided you don't use 
very large amounts of hydrogen (a hydrogen filled room could explode, 
but a 5 litres spark gap enclosure would do nothing more than crack).
  Now, if I was to try such an experiment, I would enclose my sparkgap 
in a small Plexiglas box, with a pipe on top and a cap fitted (but not 
glued) on the pipe. I would fill the box trough the pipe and put the cap 
on. If there was ignition,  the box would expand (that’s why I wouldn’t 
use glass) and the cap would fly off, safely. You could try circulating 
hydrogen inside the box to help quenching of the sparks.
 If air leaks in slowly, the heat of the sparks will combine the oxygen 
with the Hydrogen and moisture will condense inside the box. 
  If you have any questions regarding combustibility, power and safety 
of fuels, just ask away!
 Hope I have being helpful..
 Sam.

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