Subject: Water torch

From: [email-masked] (James W. Swonger)
Date: 11 Apr 1995 17:06:06 GMT

I have begun building a water torch, actually just the generator part,
for use with regular acetylene torch hardware. My results to date are
somewhat encouraging, but not satisfactory.

 I made some multiplate electrodes out of stainless steel, MIGed together.
Using an electrolyte of distilled water and baking soda I was able to 
produce oxygen and hydrogen at a very high rate using a rectified
transformer fed off a Variac; production started at a few volts and
was quite vigorous at 30V; about 15A current through the bath, indicating
a very low resistance. I used electrodes with about 10 square inches
of surface, and at higher currents most of the surface appeared to be
active. The SS did not deteriorate appreciably at the anode, which I
deliberately oversized. This was all in an open bucket.

 I made a closed generator out of PVC 2" pipe, and inserted the 
electrodes. The generator was L-shaped and held at a 45-degree
angle to make a V, providing a means of separating the H2 and O2.
Fittings at the top for gauges, hose, electrical contact and water
fill were put in place.

 To ensure separation of the gases I had to keep a greater electrode
spacing. This, coupled with the restricted path cross-section, increased
the electrolyte impedance; I was able to get only 5A at 40V. Gas
production was more limited. 

 I did manage to produce enough hydrogen and oxygen to establish a 1"
flame on a small-orifice torch I was using. However, this did not 
last long. The problem I encountered was that since the hydrogen 
evolves at 2X the volume rate of oxygen, the pressure imbalance would
push the water slug across the V where it would run out the oxygen 
port. 

 I had built in an overpressure cutout for 30PSI but the generator pressure
never got over 5PSI.

 Two possibilities occur to me. First, I could make the oxygen section of
the V mismatched to the hydrogen section, areawise, to create an
appropriate pressure balance. Second, I could coevolve hydrogen and oxygen
in a single chamber. This has significant benefits and obvious hazards.
The benefits are in close electrode spacing, which would greatly improve
cell efficiency, and overall compactness of the design. The hazard is
of course explosive recombination.

 I have looked at photos of commercial water torches, and I see ones which 
use a single gas tube, obviously coevolving gases. Therefore they must
either have excellent liability insurance, or have found effective means
of suppressing backflash. 

 I am leaning toward using a porous bronze filter, as found in older
carburetors, at both ends of the gas line as one means of arresting
flame travel without unduly restricting gas flow. Adding open-cell 
foam to the generator gas space might also be beneficial. Before
I try these measures and launch my own little Hindenburg, I'd be
interested to hear any pointers available on explosion suppression
techniques.
-- 
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