dagabu Posted March 28, 2012 Posted March 28, 2012 Actually, when it's all hooked up with the plumbing and wiring, it'll look more like a movie prop from a mad scientist's lab (muwahahaha!!!) . WSM Why can I actually HEAR you saying that? (muwahahaha!!!) -dag
WSM Posted March 28, 2012 Posted March 28, 2012 Why can I actually HEAR you saying that? (muwahahaha!!!) -dag Didn't I quote one of your posts with that?!! We must be thinking alike . Seriously, though; this project is getting exciting. I wish I could spend more time on it but the neccessity of supporting my family and other obligations consumes most of my time so my progress is REALLY slow. I do get to think about it quite a bit in slow moments and that's where many of the planning details gel and come together. WSM
WSM Posted April 10, 2012 Posted April 10, 2012 (edited) Didn't I quote one of your posts with that?!! We must be thinking alike .Seriously, though; this project is getting exciting. I wish I could spend more time on it but the neccessity of supporting my family and other obligations consumes most of my time so my progress is REALLY slow. I do get to think about it quite a bit in slow moments and that's where many of the planning details gel and come together.WSM I've been considering how people go about designing their cells and it seems that most folks get the electrodes and try to make the other parts of the system fit around them. I'm starting to think the best place to start is the power supply. The most universally available DC power source is a computer power supply. If your supply is designed to deliver, say, 30 amps with the 5Vdc output, that is the place to start. Remember we are mostly concerned with the amperage because current (measured in amps) is what drives the reaction we seek. So what we need to do is tailor the electrodes to the power supply, not try to make the poor power supply strain to keep up with oversized electrodes. The ideal load for a power supply (using good electrical practices) is 80%. For a 30 amp supply that's 24 amps. Now we need to determine how large our anode has to be to demand 24 amps. Since each square centimeter is using 0.3 amps, we can calculate the area with this formula: 24A(X cm2) 0.3A(1 cm2) 24 divided by 0.3 is 80, so X = 80cm2Edit:[This formula works if we're using one anode with two cathodes. For peak anodic efficiency, we should surround the anode with two cathodes (presuming we're using flat sheet electrodes), and understand that the anode has twice as much total area. To explain, Swede learned from an MMO manufacturer that the mesh anodes have about 2X the surface area of the single side dimension. I suppose they use metal mesh to save on the expensive titanium base metal. If we use one cathode, the anode is only effective on the side facing the cathode. That means about 12 amps, max, in the example above. But by surrounding the anode with cathodes, we get the full capacity of the anode. It seems that most of the available anodes these days are MMO mesh material.] The final shape of the anode isn't important electrically, but for cell efficiency the shape plays an important roll (which I'll discuss a little in the next paragraph). So we're looking for a 40 square centimeter (on one side) mesh anode. If you're working with square inches, divide the cm2 by 6.45 and the results are the area in square inches (6.2 in2 in this case). After noticing that square electrodes placed near the top of a cell tend to cause heat layering in the cell fluid unless bubbling air through the liquor to mix things up; I've concluded it's preferable to make the electrodes long and slender so they reach deeper in the cell and promote natural mixing due to the "hydrogen lift" from hydrogen gas bubbling off the cathodes. Another way to achieve this might be to use longer leads to place square electrodes deeper in the cell. So instead of a 2.49" x 2.49" anode, I'll try a 1" x 6.2" anode and surround it with two matching cathodes. Experimentation is called for, or go with your best inspiration; but by all means, please share your results with us here . More later... WSM Sorry for the need to edit above; I wrote it quickly and didn't leave myself enough time to check my facts before rushing off to work this morning. I'll try to do better next time. Edited April 11, 2012 by WSM
pyrojig Posted April 14, 2012 Posted April 14, 2012 Thanks for that great info. It is so very well put, hence the reason your probably not getting reply's. I cant agree any more about the need to start with your power-supply . It is the Achilles tendon of the whole sys. You hit the nail on the head. I myself as well as many others have built systems around the electrodes and tried to make them work with the powersupply. I must have pushed my supplies beyond their max capacity many times, burning up my 1st one in the process. It is simple math as shown above by WSM, and it will save you material and powersupplies if you follow these guidelines . WSM and Swede shared many concepts and design ideas, these now have proven to be very productive. I am pleased to learn from such knowledgeable folks .
pdfbq Posted April 15, 2012 Posted April 15, 2012 WSM, I think you hit the nail on the head here! Personally I would not bother to much with two cathodes because the MMO on e-bay is so cheap, so just use a bit more of the MMO for the desired current. To determine the size of your anode, maybe a more practical way is just to dip your big anode with a cathode in a saturated Cl- solution and see how much cm2 you need for 33% of you power suply. The 33% is because when things heat up the current gets doubled was my experience. Many people do not have spot welders, including me. As I've shown before one can use washers to attach a Pt anode.Now tested it on MMO and this on easily took 20A over 5.2V
WSM Posted April 15, 2012 Posted April 15, 2012 (edited) WSM, I think you hit the nail on the head here! Personally I would not bother to much with two cathodes because the MMO on e-bay is so cheap, so just use a bit more of the MMO for the desired current.To determine the size of your anode, maybe a more practical way is just to dip your big anode with a cathode in a saturated Cl- solution and see how much cm2 you need for 33% of you power suply. The 33% is because when things heat up the current gets doubled was my experience.Many people do not have spot welders, including me. As I've shown before one can use washers to attach a Pt anode.Now tested it on MMO and this on easily took 20A over 5.2V To pyrojig and pdfbq, Gentlemen, Thank you for the kind words. I was looking for peak efficiency and used my electrical training to discover the information I posted. I love the simplicity and effectiveness of pdfbq's "riveting" method. If you keep it tight, I don't see any problems with that method. In fact, if I had access to 1/8" (3mm) CP titanium rod or wire, I may have tried it myself. I have a hand, rivet-setting punch for that size of rivets; but any size should work. I also like the use of square rivets cut from titanium sheet material; very creative and more likely keep a tight hold on the other materials. If we stick to CP titanium and avoid alloys, this method should work well. The tighter the connection, the less electrical power gets wasted as heat. Heat isn't totally wasted and does promote higher efficiency in the cell, but too much heat is a problem (see Swede's blogs) and wasteful. Most of my cells in the past had one anode and one cathode, but my pickle-jar cell experiment last Summer had the anode surrounded with two cathodes and I was very impressed with the results . Swede's conclusion to "box" the anode with cathodes has also paralleled my own thoughts about creating a high efficiency set of electrodes. The easy availability of surplus MMO anode material these days allows us to take it for granted, but if it ever becomes scarce we'll be in trouble or have to resort to messier options (graphite, etc.). Fortunately, MMO isn't going anywhere. If anything, it's becoming more common in our lives. The best part is MMO, properly treated and handled, will last for literally years until it needs to be replaced. If we stock up with enough MMO to have spare anodes on the shelf as replacements; I don't see any need for concern. WSM Edited April 15, 2012 by WSM
pyrojig Posted April 18, 2012 Posted April 18, 2012 On the subject of spot welding. Im sure myself and others with spot welders could help with the welding needs of the electrodes . I dont see bent over ti rivets being long lasting. As WSM stated, this will usually end in heat and wasted energy after a while. I may be a dandy thing in a pinch, but over several runs may prove a big prob.
frank Posted April 18, 2012 Posted April 18, 2012 Use some Grade 1, 2, 3, or 4 Ti as proper rivets.Simply obtain a hammer and a large piece of iron (or the top of a vice) and 'rivet' the two components together. (as per my lively picture).Bending them over is a bit too lazy IMO. Buts it's a great discovery let me tell you. It is also very easy to make a nut and bolt from Ti using a tap and die + a drill and drill piece. The 'nut' will simply be a hole drilled in the washer and treaded using the tap.A square piece of Ti (like one of the pieces shown bent in the getto rivet setup) is filed down to a round bar shape (it does not have to be a precision job) and then treaded using the die.A hole is drilled in the + runner that allows the 'bolt' to fit through and the bolt screwed tight into the washer (with the MMO or Pt sandwitched in between).You could also use the drill to hold the square piece of Ti (the bolt to be) and spin it while holding a file against the Ti to round it off. A lathe would be great.Grade 5 does not work. I seen Grade 1 bolts on ebay once and they were a small fortune to purchase. F
WSM Posted April 19, 2012 Posted April 19, 2012 Use some Grade 1, 2, 3, or 4 Ti as proper rivets.Simply obtain a hammer and a large piece of iron (or the top of a vice) and 'rivet' the two components together. (as per my lively picture).Bending them over is a bit too lazy IMO. Buts it's a great discovery let me tell you.It is also very easy to make a nut and bolt from Ti using a tap and die + a drill and drill piece. The 'nut' will simply be a hole drilled in the washer and treaded using the tap.A square piece of Ti (like one of the pieces shown bent in the getto rivet setup) is filed down to a round bar shape (it does not have to be a precision job) and then treaded using the die.A hole is drilled in the + runner that allows the 'bolt' to fit through and the bolt screwed tight into the washer (with the MMO or Pt sandwitched in between).You could also use the drill to hold the square piece of Ti (the bolt to be) and spin it while holding a file against the Ti to round it off. A lathe would be great.Grade 5 does not work. I seen Grade 1 bolts on ebay once and they were a small fortune to purchase.F Hi Frank, Nice riveting description. Either riveting or bolting using CP titanium will work great if made tight enough (too loose and the overheating thing becomes a problem). If the CP titanium seems too hard, it can be annealed by heating it to red heat with a torch. Thanks for sharing. WSM
WSM Posted April 19, 2012 Posted April 19, 2012 On the subject of spot welding. Im sure myself and others with spot welders could help with the welding needs of the electrodes . I dont see bent over ti rivets being long lasting. As WSM stated, this will usually end in heat and wasted energy after a while. I may be a dandy thing in a pinch, but over several runs may prove a big prob. We'll have to wait and see. He reports some heating already but heating is normal in the electrochemical cell, even when things are done right. If the connection is or gets loose, the electrodes will likely overheat and possibly deform. WSM
WSM Posted April 19, 2012 Posted April 19, 2012 I picked up a piece of clear, 4" schedule 40 PVC pipe on eBay recently. I may just get to make a small clear (mostly) cell for demonstration purposes . I know, I know; I already have the glass cell that sits there not getting done already . The problem with the glass cell is the thing is going to weigh too much to be portable when it's filled with solution . I'll take a photo and show it whenever I get around to doing something with it... WSM
pyrojig Posted April 19, 2012 Posted April 19, 2012 I picked up a piece of clear, 4" schedule 40 PVC pipe on eBay recently. I may just get to make a small clear (mostly) cell for demonstration purposes . I know, I know; I already have the glass cell that sits there not getting done already . The problem with the glass cell is the thing is going to weigh too much to be portable when it's filled with solution . I'll take a photo and show it whenever I get around to doing something with it... WSM Love to see it. Looks like an emotional wreck from all the faces shown above .
frank Posted April 19, 2012 Posted April 19, 2012 CP Titanium is quite soft and easy to work. It is alot like brass. I think if you heat CP to red heat is gets hard as glass and brittle. At least thats what happened a piece that I heated for a long time, hotter than red heat. Glass cells (unfortunately) become translucent after a time of working. The inside seems to get etched somehow. They are nice to begin. Perspex (if using as a lid) goes translucent and cracks appear.Transparent PVC will probably go translucent (don't know though).
Arthur Posted April 19, 2012 Posted April 19, 2012 Swede replaced some electrodes once, and it was suggested that the reason for their failure was that the vessel was glass and etched glass was deposited on one electrode. Whether this was with pH controlled systems or pH uncontrolled systems I no longer remember.
Arthur Posted April 19, 2012 Posted April 19, 2012 Swede made a successful spot welder using a rewound microwave oven transformer. Build for about 2 - 2.5v and use pure copper electrodes and short fat wires. The target is about 1000 amps at 2v, short pulses of about 2 - 5 seconds should do most welds.
WSM Posted April 20, 2012 Posted April 20, 2012 Swede replaced some electrodes once, and it was suggested that the reason for their failure was that the vessel was glass and etched glass was deposited on one electrode. Whether this was with pH controlled systems or pH uncontrolled systems I no longer remember. I wonder if tap water or distilled water was used? Tap water in many parts of the civilized world is fluoridated and fluorine kills MMO by attacking the titanium substrate (as well as etching glass). I'll have to see if the glass will be affected by KCl and HCl plus current while using distilled water to make the liquor. WSM
Mumbles Posted April 20, 2012 Posted April 20, 2012 Glass does get etched by strong hydroxide solutions as well. I really don't know if the cell would make a strong enough solution to do that though.
WSM Posted April 20, 2012 Posted April 20, 2012 Glass does get etched by strong hydroxide solutions as well. I really don't know if the cell would make a strong enough solution to do that though. That's a good point. In a separated cell one side makes hydroxide ions. In an undivided cell, I don't believe hydroxide survives. WSM
WSM Posted April 20, 2012 Posted April 20, 2012 CP Titanium is quite soft and easy to work. It is alot like brass. I think if you heat CP to red heat is gets hard as glass and brittle. At least thats what happened a piece that I heated for a long time, hotter than red heat.Glass cells (unfortunately) become translucent after a time of working. The inside seems to get etched somehow. They are nice to begin. Perspex (if using as a lid) goes translucent and cracks appear.Transparent PVC will probably go translucent (don't know though). In my experience, CP titanium is more like mild steel than brass. WSM
pdfbq Posted April 20, 2012 Posted April 20, 2012 (edited) @WSM I did not reported any heat (but maybe you were not referring to me)The rivets work too well to be true. Yesterday I made another anode and clamped it just loosely. The MMO is still able to move between the shaft and the little Ti plate. Result: Still massive current. If one would do the same while connecting the wires from the power supply to the shafts there would be hardly any current possible..I'm convinced something else is going on and I think its very interesting (but it was not me who came up with why, see quotes ). About glass cells: I destroyed two! anodes before we found out it must have been my glass cell. Never had any problems anymore after switching to other materials although I think borosilicate glass wont give any issues. The jars I used were cheap IKEA cookie jars from glass, quite soft. ...I presume that the part with the homemade rivets is actually submerged below the level of the electrolyte? (ie. all of the MMO is in the salt solution).Just to bore you all, when bare Ti is used as a Cathode the non conducting Ti Oxide layer is still on the surface of the Ti. It does not magically dissappear. It becomed totally conductive by hydrogen being produced at the cathode surface (as happens at the cathode). This hydrogen dopes the non conducting Ti Oxide and it magically becomes a conductor. If the same piece of bare Ti is then used as an anode the H does not get produced and the Ti Oxide reverts back to being non conductive and the current stops flowing. If you put a high enough Voltage of say 15 volts to the anode, the oxide layer breaks down and the Ti gets eaten away. I imagine that when you rivit the bare Ti to the MMO there must be a small amount of Hydrogen produced at the interface of the MMO and bare Tiwhich keeps the Oxide layer on the bare Ti doped and conductive. Since electrons are going out of the MMO surface at the interface (as they do in a cathode)some H is being produced which keeps the (bare Ti) Oxide conductive. (I think!!!!!!!!)...Why Titanium (and other valve metals) will not conduct when used as an Anode (oxide layer not conductive) and why the oxide layer becomes conductivewhen they are used as a Cathode is explained in a hell of a lot more detail than my explanation. http://downloads.hindawi.com/journals/apec/1974/398185.pdfHydrogen doping it is!!If you dont believe Mr. C. K. DYER all the way from the Department of Metallurgy and Materials Science, University ofNottingham, Nottingham, U.K. ON JULY 6 1974 (WOULD YOU BELIEVE) then I give up.The joint that is created by the homemade rivets in not a sealed joint. The solution will be able to get in between the Ti and the MMO yet it works.It's time someone had got around to actually trying and doing it. Edited April 20, 2012 by pdfbq
WSM Posted April 21, 2012 Posted April 21, 2012 @WSM I did not reported any heat (but maybe you were not referring to me)The rivets work too well to be true. Yesterday I made another anode and clamped it just loosely. The MMO is still able to move between the shaft and the little Ti plate. Result: Still massive current.If one would do the same while connecting the wires from the power supply to the shafts there would be hardly any current possible..I'm convinced something else is going on and I think its very interesting (but it was not me who came up with why, see quotes ).About glass cells: I destroyed two! anodes before we found out it must have been my glass cell. Never had any problems anymore after switching to other materials although I think borosilicate glass wont give any issues. The jars I used were cheap IKEA cookie jars from glass, quite soft. Hi pdfbq, I have no idea what type of glass my heavy walled tube is, but It might be borosilicate (it came from an industrial environment). I suppose I'll find out when I fill it and apply current !If the glass is affected, I'll have to change things (maybe I'll end up making a lamp out of it yet . Still have that lampshade, pyrojig?!). We'll see... WSM
pyrojig Posted April 21, 2012 Posted April 21, 2012 Hi pdfbq, I have no idea what type of glass my heavy walled tube is, but It might be borosilicate (it came from an industrial environment). I suppose I'll find out when I fill it and apply current !If the glass is affected, I'll have to change things (maybe I'll end up making a lamp out of it yet . Still have that lampshade, pyrojig?!). We'll see... WSM Gottcha covered!!
WSM Posted April 22, 2012 Posted April 22, 2012 CP Titanium is quite soft and easy to work. It is alot like brass. I think if you heat CP to red heat is gets hard as glass and brittle. At least thats what happened a piece that I heated for a long time, hotter than red heat.Glass cells (unfortunately) become translucent after a time of working. The inside seems to get etched somehow. They are nice to begin. Perspex (if using as a lid) goes translucent and cracks appear.Transparent PVC will probably go translucent (don't know though). This remains to be seen. I need to run one of my cells that has clear PVC components and see how it holds up. I don't expect any major problems but Swede expressed the opinion (years ago) that it might sustain cosmetic damage from the cell liquor. Again, we'll see... WSM
pyrojig Posted April 27, 2012 Posted April 27, 2012 @ wsm .... I just picked up about 4' of 10 " scd 40 pvc tube . If I where to make a super-cell out of it , what would the height need to be in your opinion? I was thinking 2' max. I DO need some plate however to do the top and bottom. With the other half I think I'll make for mill jars like Oldguys design.
oldguy Posted April 27, 2012 Posted April 27, 2012 @ wsm .... I just picked up about 4' of 10 " scd 40 pvc tube . If I where to make a super-cell out of it , what would the height need to be in your opinion? I was thinking 2' max. I DO need some plate however to do the top and bottom. With the other half I think I'll make for mill jars like Oldguys design. Not sure which jar design you mean, as they have evolved. Strongest is the most recent design. Before Rings were added & ¼ round router-ed. Solvent welded rings added. Super strong at all joints.
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