Liquid level sensor circuit for HHO generator

Discussion in 'Power Electronics' started by Mark Flint, Apr 5, 2018.

  1. Mark Flint

    Thread Starter Member

    Jun 11, 2017
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    I have a HHO (Brown's gas) generator that produces HHO by electrolysis.
    It passes approx. 200v pulsed DC (100Hz) at 6 amps through an electrolyte of distilled water and sodium hydroxide from the positive to the negative terminal of the electrolyser.
    I am considering two options for a liquid level sensor circuit that will switch off the power supply in the case of low level:
    1) two wires inserted at the appropriate level into the the electrolyte solution with a gap between them. When the wires are immersed they should make a conductive connection via the electrolyte. When the level is low the wires will be exposed and the circuit broken.
    2) a float switch
    I prefer the small footprint and simplicity of option 1).
    I am looking for suggestions as to what things I need to consider for the option 1) circuit... can I utilise the existing charge in the electrolyte for my circuit, or would it easier/safer to supply a separate current... and what effect would either of those possibilities have on the electrolysis process?
    Thanks in advance for you comments.
     
  2. MisterBill2

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    Jan 23, 2018
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    Any level sensing arrangement is going to be more complicated by the 200 volts six amps power in the quite conductive liquid that you have. Now I have a question, which is what would the level detector do?
    If all that you need to do is to switch off the power supply the sensing system is fairly simple. You will need one sensor probe electrode, insulated from the container that the reaction is taking place in, extending down to the level at which the supply must switch off. Then you also need a fairly sensitive relay that will switch on with about 24 volts but not burn out when 100 volts would be applied. The relay coil would be connected between the sensing electrode and the negative DC electrode for the process, with the sensing electrode part way between the two main power electrodes. This would, I think, provide enough current to keep the relay engaged. The contacts of the sensitive relay would then control a power relay for the 200 volt DC supply.That is about as simple as I can make it.
     
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  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    If using DC current between probes for the sensing, then there will be probe corrosion to consider.
     
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  4. danadak

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    Mar 10, 2018
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  5. MisterBill2

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    Corrosion may be a problem with some materials but it should be possible to find a material that will have an acceptable lifetime. Possibly graphite, which is fairly inert and also fairly cheap. While I know some chemistry I have not come across "HHO", although I am quite familiar with HOH, also known as water. And I have never heard of "Brown's gas", and so have no clue about whatever reaction is going on. I am guessing that the reaction is producing both hydrogen and oxygen as gasses, along with a bunch of steam. For water plus sodium hydroxide probably a cast iron sensor electrode will work well. The relay may need to have a diode in parallel, pointed towards the positive side, so that the collapsing magnetic field will produce a current instead of a high voltage.
     
  6. Ylli

    Active Member

    Nov 13, 2015
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    HHO is a fictitious item made up by the group that claims to be able to run a car on water. It's really just a very explosive premix of H2 and O2.

    "Oxyhydrogen is a mixture of hydrogen (H2) and oxygen (O2) gases. This gaseous mixture is used for torches to process refractory materials and was the first[1] gaseous mixture used for welding.........

    The term Brown's gas refers to oxyhydrogen with a 2:1 molar ratio of H2 and O2 gases, the same proportion as in water. It was named after its Bulgarian inventor Yull Brown (born Iliya Valkov, Bulgarian: Илия Георгиев Вълков), who suggested it to be produced by the electrolysis of water to be used as a fuel for the internal combustion engine.[4] Later "Brown's gas" and HHO has become fringe science terms for a 2:1 mixture of oxyhydrogen obtained under certain special conditions; its proponents claim that it has special properties."

    https://en.wikipedia.org/wiki/Oxyhydrogen
     
  7. WBahn

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    Mar 31, 2012
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    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. Once the water level drops to that point, it is no longer in the water solution and the impedance it sees goes up enormously, thus shutting down the current. I would then be a simple matter, if you wanted something beyond this, to measure the current in the electrode and trip the supply when it drops below a certain level.

    You might also be able to use this approach even if the two electrodes are fixed at the bottom of the container. The current probably depends on the water level (and also the amount of NaOH, so that has to be controlled and/or accounted for). If it is predictable enough, then you just set a trip limit based on the electrode current.
     
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  8. MisterBill2

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    Jan 23, 2018
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    Thanks very much to Ylli for the explanation. I do recall reading the ads for instructions on how to run a car on water. 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, but aside from those problems, and the heavy tanks to carry the mixture, and the related safety issues, it may work.
    Of course, a balloon full of that mix would make a very big bang if it met a spark.
     
  9. WBahn

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    Some of the HHO and water-run car crowd have been taking cues from the homeopathy gang and claiming that things such as special taps and vibrations on the equipment while the stuff is being produced embues it with sympathetic resonances that allow it to release more energy when it is burned that was needed to create it.

    The next thing they might come up with is then 100C HHO in which a tank of the stuff has even more energy than a tank of pure HHO because of the special conditions under which it was prepared, even though there is statistically a very high probability that the amount of hydrogen is no higher than the ~0.5 ppm that the atmosphere normally has.

    Of course, once they discover that car engines are immune to the placebo effect, they will probably discover all of the wonderful medicinal properties it has.
     
  10. MisterBill2

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    Jan 23, 2018
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    That is a real possibility, indeed. 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. And the problem with pure oxygen in a humid atmosphere is corrosion. So now there would be corroding tanks full of a mixture that has a tendency to burn fast. Really a rather unsafe thing. Perhaps folks should just stick to sniffing the mix. But one spark and they could have a "mind blowing" experience. ( I couldn't resist that one.)
     
    Last edited: Apr 7, 2018
  11. Mark Flint

    Thread Starter Member

    Jun 11, 2017
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    Thank you Dana - that's very useful information, I like this solution as the controller also gives the possibility of other responses.
     
  12. WBahn

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    You can rig up a capacitive sensor without using a microprocessor -- they were around long before micros were.

    Another way to do it is to put a thermistor at the point where you want to detect the level. Then you put enough power into the thermistor to significantly change it's temperature. The temperature change will be far less if it is still submerged in water than if it is in the air above it. Depending on the material and thickness of the container, you could also do this by bonding the thermistor to the outside of the container, but the accuracy and sensitivity will suffer.
     
  13. Mark Flint

    Thread Starter Member

    Jun 11, 2017
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    Thanks for this, and a quick YouTube search shows how to build this.
     
  14. WBahn

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    Out of curiosity, what are you using the Brown's gas for? As a kid we used it for filling balloons that made a heck of a bang when they were touched with a match (I didn't have access to oxy-acet until years later). It was also good for making rubber-stopper cannons.
     
  15. MisterBill2

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    Jan 23, 2018
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    OK, I guess that the possibility of using an extra electrode and sensitive relay was not acceptable, although I never saw an explanation of what would not work. I certainly seems like a simple but effective choice, since the exact shut-off level is not terribly critical, it doesn't seem. And I also wonder what the use of this explosive gas mixture is intended to be.
    So please enlighten us as to what the new application is.
     
  16. Mark Flint

    Thread Starter Member

    Jun 11, 2017
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    Sorry for the silence on this... No, I have not dismissed this proposed solution. I imaging I would have about 200v between an inserted wire electrode and the negative terminal. I have to have that power for the main unit but think I'm edging towards lower voltage options for controls.

    Regarding the use of Brown's gas - it is mostly hydrogen by molecules, and can quite easily be separated out to be just hydrogen if desired - although oxygen is known to be of benefit also. There are hundreds of peer-reviewed scientific papers probing the efficacy of hydrogen in treating disease - and many promising results. If you would like to check out some of these papers there is a useful index here:
    http://www.molecularhydrogenfoundation.org/studies/ There is no need to store the gas as it is used in real time, avoiding safety issues of storing it.
     
  17. Mark Flint

    Thread Starter Member

    Jun 11, 2017
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    Mostly for medical use.
     
  18. MisterBill2

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    Jan 23, 2018
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    Thanks.
     
  19. WBahn

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    If you do want to get just the hydrogen, the just use an electrolysis apparatus that collects them separately. It is a very trivial setup since the hydrogen is liberated at one electrode and the oxygen at the other. The typical lab-scale apparatus is nothing more than a U-shaped tube with one electrode in each vertical segment (or something equivalent). Ones intended to generate more gas usually have a port at the bottom of the U that connects over to a larger beaker/tank with the water/electrolyte solution in it.
     
  20. Mark Flint

    Thread Starter Member

    Jun 11, 2017
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    Yes, if I wanted just the hydrogen that's what I would do.
    Thanks.
     
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