If to use any immersed wires system there will be rather hard times about electrolyse causing current. The least turbulence or inuniformity and there is false-trigger. I would vote for brutally mechanical rod of some plastic containing small magnet ar base near the hinge what hits a hercone mounted in the feet. At the ebay those are sold for three coins a wagon. Capacitative method is not bad, but it will cost much more nerves, time and money, and who know how it reacts with acid solution and hard electrostatic field between trodes.
Take a hercone, thats ultimately stable.

 

RE:<<The typical lab-scale apparatus is nothing more than a U-shaped tube>>

It WAS about century ago while the better systems wasnt invented. And need to say, for any immagineable practical use it is completely sensless. In the HHO welding machines are used as the industry standard two systems - plate to plate with a distancers, and plate count be in tens or near hundred if 220V. Other is roll of two plates with screen as the distancer.

Both ways, the single cell voltage MUST not exceed the 2...max 3 Volts. Forget about 200 V if only the aim was not make a super-long train of cells. About 100 kHz - there indeed are some speculations on the net, of creating a devices for space-time energy harvesting, travel with over-light speed and high frequency decomposition of water better than DC may do. Havent tested myself, so cannot comment, but the scientific basis for such hypothesis is rather very poor.

My advice, make a cell of as simple You can and apply a ATX computer PS with modified microscheme, let be able to steer the current and it be CC instead of CV PS. The 5V and 100 A is more than enough to pull the 2 cells of at least 10 dm2 sqare each and it gives a gas allowing to weld a railway rail.For welding a car its enough with 60-100 W HHO torch.

And last, You cannot get hydrogen if You generate the HHO. The same way that You cannot get out the clean water if You have maked a coffee. If want a water, then dont produce a coffee, and if want a hydrogen then dont make a HHO gas. Make a hydrogen instead.

 

RE<< I imaging I would have about 200v between an inserted wire electrode and the negative terminal>>
That is the average method of boiling the tea in most of russian prizons and russian modern slave-camps. Just the slaves there are not given a tea pots, heaters or any electric devices, but they are using a two beard razors and wire pieces into network. Yes, its unsafe, its bit poisonous as the chromium and nickel are dissoluted but at least the thousands or even a million of modern prizoners in this way today was got the warm tea, and will produce it tomorrow and after. My question- how You was aiming to stop the damn warming effect?? There is only way known to me - to decrease the voltage.

 

RE:<<A very simple option (depending on the mechanics you are stuck with) is to just place one of the electrolyzing electrodes at the level at which you want things to stop>>
Good idea but not easy to use, as the HHO gas is hardly forbidden to keep even a smallest volume. The only way to stay alive is to keep the level always not lower as milimeter or two below bath upper cover. While electrodes cannot be 1 mm high as they need sth about 5-10 Amp per square dm2.

 

RE<<The biggest problem that I see is that since hydrogen is a fairly smaller atom it will tend to leak off a bit faster than the oxygen>>

One way yes. Probably I had told here somewhere my young engineer epoch experience with 6 gas-chromatographs consuming a hydrogen like horses. We kept a gas bottle in the lab near tables with that machines until the work safety inspection came on. They say wow, you shall blow up. I say, no, we work this manner at least 5 years and have trained all the personell to wear no synthetic fabrics and soles, and we always work at windows opened etc etc etc.

But the ball was going all the time in one basket so verdict was - three days to set the "gas house" outside the building. That was early 80-ies, the communism, long queues for simplest sausage in the shops, so how to obtain a stainless thick-wall pipes for lab line there was no any chances, but somehow I got the bunch of 6 outside and 4 inside the brass pipes of 2 meter long each. After tricky witchcraft I managed to take em in one long, hanged on the wall and laid out to the gas bottle.

Switch on, bottle output manometer shows 10 atm, but all our chromatographs says - no gas at all. I screw off the pipe, put it in the earlobe - indeed no gas. I thought I have soldered metal bubble , so took off the line of ceiling, bend it back straight, with wire tested where the defect will be - nowhere. Thought, may be somewhere a giant crack?

So, about half kilometer we had a Daugava river near the kilometer wide and shallow, so I arranged the helpers and we walked with the pipe to river where I applied a car tyre pump. Everything was OK, air is taking out in the end and no bubbles where solderings. Damn, probably I had mis-dreamed I had a problem? So put the pipe back of wall, switch on - nothing. Down 10 atm, upstairs zero atm.

Next morning angry as thousand of cheeneezes I take it down again, arrange a more helpers, walk to the river together an hydrogen bottle... OH MY! There I felt I have deserved to take back my diploma to my Alma Mater as unearned...

the WHOLE pipe looked in river like women sock filled with air under water, The gas bubbles was everywhere on the surface. Later I seen how the hydrogen lines are organized in the real enterprizes like Alfa semiconductor factory - the 100 meter line was 25 mm stainless pipe with 3 mm inner hole, and in he way they had loss about 75% of gas. So it is with the hydrogen

But not in the HHO torch thing, because no-one except suicidal persons may have to soft pipes longer as meter, one and half, or maximum maximorum two. Thus if the pipe diameter is one milimeter or two, then surface is small, the gas velocity is high, so the loss is really tiny (but still existant).

 

Simple, inexpensive float switch.

https://www.grainger.com/category/float-switches/pump-controls/pumps/ecatalog/N-cc8#link-WP28019

This could directly control power to your power supply.......like an interlock......or this or smaller unit could control a simple relay to your power supply. For your application, if you have surface turbulence....you want two floats for monitoring two levels. A level differential prevents relay chatter.

You should be able to find cheaper units on ebay.

 

RE:<<Of course, a balloon full of that mix would make a very big bang if it met a spark.>>

No, sir! Ther is not any need for sparkle to blow it up. Half life working with that sh** I have learned that if want to survive until pension age, the some specific rules must be obeyed:
1) Hydrogen has INVERSE warming curve. All gases compressing warms but releasing cools. Hydrogen straight vice versa. It become damn hot just because loss of pressure. Practically it means, the easiest way to blow the bottle is to open a tap rather fast. No need for any sparkle, just screw fast. Therefore non-suicidal persons open the bottle VERY VERY slow.
2) The sparcle must not obligeously be seemable, as it is enough with one micrometer sized sparcle to trigger `good buye my beautiful life`. The any even mild contact steel to steel generates such spark invisible, therefore ALL instruments for hydrogen bottle operations, screwing etc are copper metal and nothing else.

 

RE: BR549
Yepsssk, exactly such as You show, only 1000 fold cheaper was those I reccomended upper. Well proven and stable inspite of cheapness and China origin.

 

RE:<<Of course it would be far less efficient than running it on gasoline, and the serious spark knock would destroy the engine in a short time>>
I had worked wit LPG systems installation some years, I know the 99% of cars EVERY tact blows tiny amount of burning flame back to input collector, but when the gas pedal is fast pressed in or depressed out, then this backfire is rather large, to blow uo all what is inside the collector. Therefore in K-Jetronic system was so difficult with LPG that it had rather large intake volume, normal car may be half litre, but there 10 liters or more. The only solve was install the one-way clapan what dehermetizes system saving the metering platelet form damage.
I think running on HHO is clear suicidal and even run on the H2 bottles yet was proven in Moscow city bus park at late 80ies with 60 busses, as it was proudly advertized in many newspapers, yet somehow none was surviving until 90ies what means the infamous end.

By the way, dont You minded how to compress the produced gas. I have witched about 300 atm compressors, but 1,5 kW allows to fill one alone bottle in abouut 20 hours!!!! Plus to said, dont forget about inverse heating effect when it is flowing into the bottle. Boom!

 

RE:<< HHO proponents claim that it has special properties>>
But it indeed has.... damn volatile, damn explosive, damn dangerous, damn effectively burnable with no any sooth residue, with strongly neutral flame of 3100 C, and about 3,50 km/s flame zone dilation speed (half of fist cosmic speed). Boom!

 

RE:<<And the problem with pure oxygen in a humid atmosphere is corrosion.>>
Not so tragic at all.
The AISI-306 is rather applicable and AISI-316 is just brilliant.
For other details - PVC unacceptable, Polypropylene and polyethylene as well the PTFE are welcome. Organic glass - partially usable.

 

Simple, inexpensive float switch.

https://www.grainger.com/category/float-switches/pump-controls/pumps/ecatalog/N-cc8#link-WP28019

This could directly control power to your power supply.......like an interlock......or this or smaller unit could control a simple relay to your power supply. For your application, if you have surface turbulence....you want two floats for monitoring two levels. A level differential prevents relay chatter.

You should be able to find cheaper units on ebay.

Thanks. I did wonder about the turbulence factor. I had in my mind that if using a float I would set it a little higher (as I have room) and just allow it to drop plenty enough to avoid false trip. At the end of the day the humble float switch might just be the best solution.

 

If you already have two electrodes in the tank for the pulsed current, why not place them above the floor of the tank at the level you want the process to stop? Metering the current through the circuit gets you level detection with no additional sensing components inside or outside the tank. Shunt resistor > comparator > retriggerable monostable > control signal output.

ak

 

If you already have two electrodes in the tank for the pulsed current, why not place them above the floor of the tank at the level you want the process to stop? Metering the current through the circuit gets you level detection with no additional sensing components inside or outside the tank. Shunt resistor > comparator > retriggerable monostable > control signal output.

ak

Thanks for the suggestion, but too much work as the electrodes are in the centre of the two ends of the pipe (cylindrical design) and cannot be accessed now without cutting the pipe. I think I'm going with the float switch.