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Registered Member #1864
Joined: Tue Dec 16 2008, 09:30PM
Location: Clinton, IL
Posts: 2
To get the general warnings out of the way (yes I appreciate them, if I missed something let me know).... I have done research into HHO generation, don't plan to store any significant quantities of it, understand that I believe 20mJ of energy is all it takes to start ignition, and know that if i do wish to ignite any significant quantities I better be a good distance away (preferably while filling the balloon or whatever as well), and to never operate the equipment indoors.
I have recently been prescribed oxygen at night with a humidifier. Looking at the humidifier itself it looks like it is basically the same design as most of the HHO generator bubblers I have seen.
As I have considered building an HHO generator for fun (maybe eventually playing with the vehicle stuff but not for a long time) it made me wonder, if running almost pure O2 through about 3-4" deep water makes a noticeable difference in humidity (irritation/pain from dry air vs humidified), how much water vapor/humidity is actually coming out of most people's generators?
There are things I mainly am curious on.... 1) How much vapor is coming out of an average system? and depending on how significant: 2) Will running it through a distillation rig cause the vapor to condense (and how much reduction would there be) 3) Are there other options that can be made to remove water vapor without significantly increasing the risk of an explosion?
I know there are better people to ask this but the question just came to me as I am trying to get to sleep at 4AM. Hopefully this also will reduce any harassment on spelling, phrasing, etc. but I doubt it :)
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
You are off by afactor of about 1000 on the ignition energy, it is closer to 20 uJ. (micro joule).
You should assume that you will have an explosion and design your apparatus such that it can handle it safely. If not you might get showered by supersonic pieces of glass,
How much water will be in your gas depends on a lot of factors, there is also a large uncertainty about tiny droplets contained in the gas. To be sure you should test it, just mark the water level and let it run for 24 hours and see the difference.
Yes, condensation will help a lot, how much depends on the temperature you use. There are other methods, it depends on how dry you need it to be and the volume needed.
If at all possible, store the hydrogen and oxygen separately, you are asking for trouble if you mix them before needed.
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529
Be very careful about the ignited gas getting back into the cell. One of mine did, and blew up (I used NaOH so I got a couple of chemical burns. My gen two used several methods. The cell was in a PVC shell, the gas went through a bubbler directly, then a piece of foam, then through 2 loops of tubing with water at the bottom, through the major length of the tubing, through another flame arrestor, and finally a flow choke. If it struck back, it never got past the first flame arrestor.
Arrestors are fairly good at removing vapor, a PVC tube filled with foam may work well. Be careful of using metal chambers, look into hydrogen embrittlement.
Registered Member #1864
Joined: Tue Dec 16 2008, 09:30PM
Location: Clinton, IL
Posts: 2
Bjørn wrote ...
You are off by afactor of about 1000 on the ignition energy, it is closer to 20 uJ. (micro joule).
This was an error due to the combination of the time of the day and a mix of prescription medications and caffeine, I did mean micro joule.
Thanks for the warnings again and I have seen videos of what has happened with people blowing up their cell or using a !metal! container to store the gas.
Would there be any point in adding something along the lines of a rupture disk or just flame arrestors, etc.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
You might just design the cell to contain any HHO explosion, if you can look up or compute the maximum pressure (with no initial compression). A rough guess is on the order of 100 psi. Could be locally, momentarily higher because of pressure wave reflections / detonation behavior.
One reference is pages 7 and 8 of But I just noticed that its focus is on H2-Air mixtures. H2-O2 mixtures could achieve a bit more than twice the energy release per unit volume; that factor would be divided between a larger temp. ratio and a larger pressure ratio.
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
If I set fire to a mixture of H2 and O2 it will explode- the flame will reach roughly 2600C. The pressure will rise in rough proportion ot the absolute temperature, so about 10 fold. The peak pressure will be something like 150PSI. Now have a look at this page and see what that sort of overpressure might do. I know it's only a little explosion, but that might be all it takes. Incidentally, the answer to the original question is that the gas mixture will be saturated with air (and carrying some more as spray). At room temp that's something like 3% v/v
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529
Note that the pressure is not the only determining factor, the flame front speed is very important. Hydrogen Oxygen reactions have very high flame from speeds, and will often reach DDT, or deflagration to detonation, depending on your chamber design. DDT puts very high stresses on a chamber. I was only saying that for info, A chamber capable of 150 PSI would probably suffice (I would go 300), DDT becomes a problem with repetitive detonations.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
Now have a look at this page and see what that sort of overpressure might do. The part about overpressure calculation (explosive) is, by a large margin, the most lame and weakly presented section I have ever seen on Wikipedia! A formula is stated with no units of measurement for W and v, no dependence on the explosive material, and the wrong name (Wiebull). S/b Weibull, not the Weibull of probability science but Ann Weibull, who measured explosions within blast containment structures.
Then we move to the table: Does not give adopted explosive quantities or containment volume. Does not address conversion of listed explosive materials to TNT equivalent. (and what is potassium chlorate doing in a column with explosives?) The right column gives overpressure effects taken from some completely different reference ... aha! The cited reference is a 9/11 conspiracy film. That could explain all the stupidity, so I'll say no more.
Rich
[edit] A better reference for air blast effects is tables 4.2-1, -2, and -3, on pages 73-75 of this big document: . That's the best I could come up with today, based on an old memory of an effect level called "incipient small mammal damage". Not that any of this has much to do with explosion of HHO in gram quantities.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I am locking this thread since the consensus of experienced members is that the experiment clearly exceeds the hazard limit with which 4HV.org wishes to be associated
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HHO Generation - Bubbler
