Why can't I build my own CD Ozone Generator?

[MarkS]

I've been thinking about this for awhile now, and considering the cost of an ozone generator, DIY is a definite option.

Here is what I have in mind, with obligatory rendering...

Take two 316 stainless steel tubes, one 3" OD and the other 2" OD, both 12" long. Weld two 1" lengths of 1/8" threaded rod to the ends (electrical connectors). Cut grooves in two 6" x 6" x .5" Teflon plates to seat the metal tubes. Fill the grooves with silicone as a seal. Cut a piece of 3" PVC pipe to sheath the 3" steel tube as an electrical insulator. Drill two holes in the top Teflon plate for the threaded rods and one hole in each plate, between the metal tubes, for John Guest fittings (air in and ozone out). Using an old microwave transformer (which I have), connect the two wires to the threaded rod, making sure all of the electrical wiring is fully fused and grounded. Four threaded rods, one in each corner of the plates would bolt the whole contraption together(not pictured).

http://reefcentral.com/gallery/data/500/1010Ozone_Generator.JPG

Why would this not work? I FULLY UNDERSTAND the dangers involved with the amount of electricity I will be dealing with! I would take every precaution. The questions I have is will this design work, and if so, how do I measure the ozone output? The generators I see for sell are rated in grams per hour. How do they arrive at that rating?

Any advice on the design? Any input, other than the expected cautions?

[MarkS]

Wow. Either nobdy knows or they are scared to answer. :confused:

[69vette]

Have you checked the price of an O3 generator for a spa?

[MarkS]

Hmm... Seems I need a di-el-ect-ric between the two tubes. Where can I get a glass or Phenolic tube with an ID of 2"?

I still cannot believe that nobody knows nothin' about this subject. :confused: If I kill myself trying this, it is not your fault! ;)

[69vette]

http://www.americasbestpoolsupply.com/view_prod.cfm/DepartmentID/25/CategoryID/298/ProductID/5611/ProdCount/2/StartRow/1/PageNumber/1

[MarkS]

Thank you, that is definitely an option. However, I'd like to keep this thread about DIY alternatives. ;)

[H20ENG]

Corona Discharge 101: :D

It can easily be done, but you will need tighter tolerances. And those Microwave transformers are dangerous, due to the amount of power they can put out. Most generator power supplies only put out milliamps. Those micros put out like 10 amps, and the arc at 15kV can jump at you from about an inch away and your toast.

That said, on to the discussion.
Take your 3" tubing (this is huge for a reef tank, and could quickly oxidize everything!), and electrically ground it.
Then use a thin dielectric (Plastic is the easiest to use, but glass is a way better insulator) inside the tubing. It needs to be touching the outer tube.
Then get some perforated stainless steel sheet metal, roll it up and rivet it together so that the perforated "tube" has about 1MM gap between the tube edge and the dielectric. Hook this perf tube to the 12-15kV transformer, and ground the transformer in the same spot as the outer tube ground.
Turn it on and listen to its Dr. Frankenstein- esque hum and cook your nose with the ozone.

These are much easier to make in a plate style. Take some metal mesh (window screen), and attach it to a piece of glass or acrylic. Attach the second piece of mesh to the other side of the plate. There needs to be a small air gap, as that is where the corona occurs. Slide the whole thing in a piece of pvc pipe for insulation and containment. Cap both ends with airlines going in and out for your input and ozone out.
You can also use a neon sign transformer, as they put out the needed kV, but only run in the 15-30mA range. You just need to hook one lead to the electrode, and the other lamp lead to the "ground" side of the cell.
Come to think of it, your high current power supply from the micro may simply toast your generator "cell", but not sure.
You can also just get a 185 peak nM UV lamp and ballast and enclose it to run your air through. You will have less corrosion problems than a CD type generator.
Ozone will convert some of the nitrogen in the air (especially if its moist) into nitric acid, which eats even stainless steel. This is why most commercial units use an air prep unit. They take the air, concentrate the oxygen to about 95% and drop the dewpoint to neg60 deg F. Virtually NO moisture to foul the unit.
This is less of a problem for our tiny generators, but you do want to be able to get to the cell and periodically clean or replace the electrodes. (The Red Sea generator I had was inaccessible)

Ozonizers are rated usually based on pure dry oxygen feed gas. Even then, you will be lucky to get 6% of the oxygen to convert to ozone. This is an industry average and yes the stuff at 6% is VERY powerful. That is why the ozone is rated in mg/h or grams/hr, because there is so little actual ozone coming from the machine

The Del Ozone machines I used to run made 6lbs a day at full load. We ran them only at 50% (even then they turned off from the ORP controllers) on the 375,000g tanks FULLY stocked with huge fish, sharks, octopus, and every other big-poopin ocean creature out there. We did not have fractionators on the big systems (NOT my design) and the ozone kept it up fine.
A DIY O3 generator can most definitely be built, BUT for as cheap as the Ebay spa generators run, MY money would go that way

Sorry for the ramble, been a long day already.
Play at your own risk...
Chris

[MarkS]

How "thin" should the dielectric be? I was looking into Phenolic resin, but could not find it thinner than 1/8". I figured it would need to be less than that, but I am not sure by how much.

So, it's metal->dielectric->air space->metal?

[H20ENG]

"So, it's metal->dielectric->air space->metal?"
Yes:)

The glass in a big unit at work is about 1/8" thick. I have used 1/8" acrylic before with the screens and a neon transformer and it worked fine.

[MarkS]

Who says it has to be tubular in shape? Why not use two metal plates and one glass plate sandwiched in acrylic? It would be cheap and easy to build.

http://reefcentral.com/gallery/data/500/1010Alt_O3_Reactor.jpg

[H20ENG]

I have made them long and thin to slide into a pipe.

From my garbled first post...

"These are much easier to make in a plate style. Take some metal mesh (window screen), and attach it to a piece of glass or acrylic. Attach the second piece of mesh to the other side of the plate. There needs to be a small air gap, as that is where the corona occurs. "

[MarkS]

Originally posted by H20ENG
I have made them long and thin to slide into a pipe.

From my garbled first post...

"These are much easier to make in a plate style. Take some metal mesh (window screen), and attach it to a piece of glass or acrylic. Attach the second piece of mesh to the other side of the plate. There needs to be a small air gap, as that is where the corona occurs. "

Yeah, I understood that. I just inverted it in the rendering.

Using your idea, how do you attach the screen to the plate and how to you keep the other piece of flexible screen at a set (and tiny) distance from the glass?

[H20ENG]

I used tiny dots of hot glue on both the screens. Dont forget to cut the screen 1" smaller than the plate to avoid arcing.

[MarkS]

Originally posted by H20ENG
I used tiny dots of hot glue on both the screens.

OK, so on one side, I apply the screen and hold it down with hot glue and on the other side, I apply the hot glue and lay the screen down on the glue? Sounds REALLY simple. Too simple in fact. ;)

Originally posted by H20ENG
Dont forget to cut the screen 1" smaller than the plate to avoid arcing.

That was going to be my next question... So... Is the PVC tube going to resist the ozone sufficiently or should I spend extra on Teflon?

[Cosper]

Risky business..

[jman77]

I wouldn't do it .... I've heard of DIY Generators catching fire...more than on one ocasion. I don;t think this DIY is worth the risk.

[Pyrojon]

What about building your screen - insulator - screen assembly with a flexible insulator, then roll it up into a tight spiral to insert into a pvc tube. Seems that you could get much more output in a smaller space.

[jman77]

I know of people making them by sandwiching two sheets of metallic screening between a glass windowpane and using a neon sign transformer to power the thing. Again, i don't think this thing is worth it. Ozone has the potential to be very harmful, and this DIY could burn down your house. Why risk that for only a couple hundreds bucks ?

[H20ENG]

Just use little dots of hot glue or silicone to stick the screen to the glass. That way air can get around the screen mesh. This setup hums due to the 60Hz vibration of the screen, so be forwarned.
Our Big DEL units used stainless steel, water cooled housings. The tubes were surrounded by water to keep them cool. The tubes had tiny dimples inward to center a strange cold cathode lamp. The lamp I believe had argon in it, and only one end had a terminal. The lamp glowed red when turned on (from the gas inside, not red hot). There was a sight glass that you could see the bright purple corona around the red glow of the lamps.
The actual ionized gas was the electrode, the lamps' glass the insulator, and the housing was the ground. *****in cool.

Pyro, Yep, that'd work, too.
The unit I have at work right now (for odor control on the dumpster) uses glass tubes, wrapped in sheet metal. Then there is rolled up mesh inside it, with pop rivets acting as the spacers to achieve the air gap.

Some of the biggest machines I've seen were at water treatment plants. Vessels the size of a bus.
The cells were 2" glass tubes, silver coated on the inside. The tubes were slid into a water cooled vessel similar to the DEL.
A metallic "Brush" (think of a chimney sweep, bottle brush, or those pond filter brushes) was inserted into the tube the whole length and the brush center rod hit with 20kV.
The brushes dispersed the power along the whole length of the tube to eliminate hot spots on the coating.
I have a tiny coralife unit that is simply a ball of metal mesh inside a tiny vial with airlines in and out.

The principle is very simple on these units, just dont get fried....

[RobbyG]

Your going to mess with a Magnatron from a microwave?
The first time I pulled a microwave apart, the Magnatron Zapped my "Fluke" voltmeter into dust in a fraction of a second. This whole idea falls under the heading of "Not worth it for the cost of a factory unit". One mistake and the reaper will have your Wrasse.

BTW I have a very old Ozone unit and it just seems to use a flourecent light ballast and nothing else. Why the Magnatron?

[MarkS]

Originally posted by RobbyG
Your going to mess with a Magnatron from a microwave?
The first time I pulled a microwave apart, the Magnatron Zapped my "Fluke" voltmeter into dust in a fraction of a second. This whole idea falls under the heading of "Not worth it for the cost of a factory unit". One mistake and the reaper will have your Wrasse.

BTW I have a very old Ozone unit and it just seems to use a flourecent light ballast and nothing else. Why the Magnatron?

No no... Not the Magnetron. That will not help. What I need is the transformer that powers the Magnetron. It takes 120v DC and converts it to around 5000v DC.:eek2:

[RobbyG]

5000 VDC Hmmmm that would be like getting shocked by 8,000 volts AC! Good luck buddy,, hope the Will is made out and the morgage is paid up :)

[jman77]

lol.....

[MarkS]

Originally posted by H20ENG
Our Big DEL units used stainless steel, water cooled housings. The tubes were surrounded by water to keep them cool. The tubes had tiny dimples inward to center a strange cold cathode lamp. The lamp I believe had argon in it, and only one end had a terminal. The lamp glowed red when turned on (from the gas inside, not red hot). There was a sight glass that you could see the bright purple corona around the red glow of the lamps.
The actual ionized gas was the electrode, the lamps' glass the insulator, and the housing was the ground. *****in cool.


That really got the old gears turning!

What if I went to one of my local neon sign shops and got them to make me a coiled glass tube, filled with argon and with only one electrode? I could also pick up one of the sign transformers.

[H20ENG]

You'd have to then create the air gap and a ground around that whole coil, virtually impossible. A straight tube would be plenty. The one electrode setup used a huge X former at 208V primary, 12kV sec. The Neon transformers are different, as both leads are hot. You would have to build the cell so that the outer"ground" was not actually grounded so you could connect the second lead.