What's the best plate configuration for me?

[cpaiin]

Hi! I've been interested in this stuff for awhile, and my goal right now is to make a torch. Anyway, like the title says, I'm not sure what the best configuration is for my plates. right now it's -+-+-+-+-+-+ (12 plates total). I was running it on a DC 13.8 Volt power supply at about 18 Amps. I tried measuring its output once, and it seemed to be at about 1/6 liter per minute!! By reading others results, this seems INCREDIBLY low for the amount of amps.

My goal right now is to have 2 of these setups connected to a 12V power supply running anywhere from 30-70 amps. However, i think a different plate setup might help a lot! If you have any other suggestions, let me know! I have a few more details about my cell below. Ask if you have any questions. Thanks!

Dry Cell
12 Plates
Stainless Steel T316/316L
Plate Size: 6 x 6 x 0.018"
1/16" thick gaskets
Electrolyte: Potassium Hydroxide (KOH)

[nst6563]

You could try -NNNN+NNNN-. There are many configurations to try, you may just have to spend some time experimenting with them. The +-+- type of config is known as brute force and normally requires a PWM to control the heat (usually generates really good productions though)

Here's some things to think about:
Do you have holes in your plates? Check out Weldon 16 (do a search on the forums) if you haven't already.
Have you done any etching or media blasting to increase surface area?
Have you passivated your plates?
What electrolyte are you using and at what concentrate?

Personally I use -NNNNNN+NNNNNN- with smaller plates 4"x5". Currently finished blasting and waiting to passivate them (need citric acid).

[cpaiin]

Thanks for the help! I can't post pictures tonight, but I will be able to soon.
I do have holes in my plates. I'll describe them best I can. I have three on the top and three on the bottom, parallel to each other. Reading around, it seems that putting Weldon 16 around the holes is a good idea. I'm not sure why this is though.
I have sanded my plates, but only a little and I guess sand blasting with nickel slag (or is it copper??) will do better for surface area.
I have no idea what passivating my plates means, so hopefully you can enlighten me
and the electrolyte I use is KOH with VERY small concentration. With the setup I've been using, it would draw way to many amps with even a 1/4 teaspoon per gallon of distilled water.
I've just ordered more parts, 14 more plates and the same gasket. Hopefully I can make this setup more efficient. I hope to save my other cell also and maybe use both at once.

[nst6563]

surrounding the holes with weldon16 seals the edges so no current can take a shortcut and jump from one plate to the next - and is thus forced to use the rest of the plate area to jump.

Sanding will do, a lot of people I've seen do it with one of those palm sanders. I've seen reports and youtube's of blasted plates and their performance due to the increased surface area. I did etch my plates before, but have switched to blasting as there is noticeably more area. I don't use nickel or copper, but rather just plain mixed grain silica/sand. It seems to provide a nice porous finish. (take caution, blasting will warp your plates - there's info on this in the media blasting thread too)

There is a complete thread on passivating. Basically it replaces/heals the protective chromium oxide layer on the surface of the SS. It's a very easy process and just doing a search here will bring up most of them. Simply clean the plates good (some use Acetone, vinegar bath, alcohol, ultrasonics, etc...whatever will get the plates clean) and then a bath in a Citric Acid solution (10% I believe is the "norm") - if not heated to around 160f, then leave in for 2-3 hours. Followed by either pure O2, exposure to normal air, or a bath in an oxidizing agent such as peroxide (I'm experimenting with this one).
Once passivation is done your plates should be less susceptible to corrosion and last longer while maintaining a high efficiency.

[cpaiin]

Awesome! I'll get the plates sanded a bit more, change/experiment with the plate setup and everything else you've said. Hopefully I'll be able to improve efficiency. One last thing for now, the holes on my plates aren't staggered. Is this a major problem?

In the meantime, take a look at the pictures of my setup so far (and don't make fun of me too much :P)

[nst6563]

I'm not an expert by any means as I've only been tinkering with the hho units for about 3-4 years...and have really only gotten serious in the last 2.

System looks good - better than the frankenstien's lab setup I have going in the basement.

Non-staggered holes - I have no idea. I see it mentioned that yes it improves efficiency, but the holes in my plates aren't staggered - just sealed the edges with weldon16.

A few suggestions I may point out:
It seems you only have 8 bolts holding it together. Nothing wrong with that, but if you get warping of the endplates or leaks of any kind, you may want to consider adding more for pressure distribution. This would minimize the warping and keep even pressure across the gaskets. The cell I'm putting together uses 14 bolts & washers + 2 bolts for power connections (it's 37 plates though).

If you're using basic vinyl tubing, it gets very pliable and stretchy when warm. I don't think the PVC based tubing does that until much higher temps, and the re-enforced tubing is the best I've used.

If you don't blast the plates, definitely sand them. Pick a grit and go from there. When I sanded I used 180 and 250 in patterns of /\ and |- (diagonals and horizontal/vertical). Now I blast.

Clean the plates with alcohol/acetone/distilled vinegar/etc. Don't touch the reactive surfaces with your hands afterwards. handle by edges or use clean laytex gloves (you can get like a ton of them at harbor freight for next to nothing).

Passivate the plates (use citric acid - easiest and found by most industry tests to be most effective - good place to get it is wine/beer supply shops).

Definately use weldon16 to seal the edges and around the holes. That should improve your efficiency a bit right there.

*not sure if the order of the last two make a difference.

If you don't have a flashback arrestor, get or make one (plenty on this site or google on them).

Above all...search the forums. There are a LOT more experienced people around than I.

[cpaiin]

Ok, so what exactly is citric acid? Something like this in the link?
http://www.google.com/search?q=Citri...34deac8855874e

[nst6563]

yep - that's the stuff. Do a search on the concentration of the bath, I think it's around 10% by weight.

[cpaiin]

One more quick question. If you look in the pictures I posted, you can see that the nozzles (or whatever they're called) are glued on. I used Marine Goop first, and on the top I have liquid electrical tape (the red stuff. I might have actually mixed them together, can't remember). I'm just curious if the KOH, or any other part of the setup, will eat away at these glues over time and ruin my water/plates.
Thanks

[cpaiin]

Alrighty, so I finally got the Citric Acid and had the plates soak. Unfortunately, I didn't think to look at the amount on the bottle and didn't think how much water I would be using so I ended up with about a 4% concentration. (pretty dumb move, but hopefully nothing serious) Anyway, I let it soak for a quite a few hours, more like a couple days. They are air drying as I write, but noticed that there seems to be stains on the plates from the Citric Acid. I only used pure, distilled water, so the residue should be all from the Citric Acid. I pretty much assumed this would happen from the beginning, but just followed the steps. Is this a problem, and should I wash it off with distilled water?

I know it's been awhile, and I hope my deviation from the steps doesn't negatively affect potential results, but I guess I can do nothing but accept them if they do.

Thanks for the help!