How to build your own Ozone Machine for cheap
DISCLAIMER: This is dangerous. If you breathe in too much ozone you might die.
Ozone (O3) is one of the most powerful known oxidizers. As a disinfectant, it is about 3,000 times more effective than chlorine. It will kill any kind of bacteria, virus, fungus, yeast, or any other living cell on contact, and it will generally wreak havoc with any kind of organic molecule. And yet it's remarkably fun to play with.
Ozone lacks a key property that makes disinfectants like chlorine and fluorine so harmful -- the ability to persist in the body. Primarily because it spontaneously reacts with itself to revert back to normal oxygen, ozone does not typically penetrate deeply into tissue or persist in the lungs or blood or elsewhere in the body. The most significant risk when playing with ozone is to the lungs, which it can severely irritate. Great precaution should be taken in that regard. If you are asthmatic find something else to build.
Ozone is widely used for disinfecting or sterilizing drinking water, aquarium water, waste water, and pool/spa water, deodorizing/disinfecting air or surfaces, sterilizing operating rooms, food preparation, food storage, insect and disease control in grain storage, and for a number of useful chemical reactions (see wikipedia article on ozone).
I have used it to store bread, preventing it from becoming stale or growing mold; curing athlete's foot in just a few days (by enclosing the foot in a plastic bag filled with ozone once per day); destroying airborne and surface mold and mildew and associated odors after basement flooding, disinfecting and deodorizing a dryer after a possum died in the exhaust vent, neutralizing noxious fumes from sprayed insecticides, and general deodorization.
THE PRINCIPLE OF THE MACHINE
The machine works by discharging electrons into the air (called a corona discharge), which encourages the available oxygen molecules (O2) to rejoin together into ozone (O3). Overlapping sections of metal screen are separated from each other by glass and given opposite alternating charges of around 10-20 kV. The high voltage causes electrons to free themselves from the the metal, and into the surrounding air, blocked by the glass from reaching the oppositely charged electrode. Localized sections of glass can get very hot, so Pyrex is used. The free electrons then combine with atmospheric O2 to form it into O3, (i.e. 3 O2 → 2 O3). To a lesser degree it also encourages the formation of compounds from available N2. It's a good idea to exclude materials other than the metal and glass, such as any kind of glue, from the reaction zone, as such materials would very likely become subjects of further reactions. The plasma effect from the freed electrons causes a blue glow around the overlapping metal elements. Air is blown through the reaction zone to move the ozone out and new oxygen in, and this also helps to preventing overheating. The outside of the active element should remain cool enough so that plastic is an acceptable material for the enclosure.
BUILDING THE MACHINE
To build this ozone machine you'll need about $30 worth of parts from eBay, plus stuff some other odds and ends you might already have around the house. Here's everything you'll need:
• A pyrex glass guitar slide (prefereably large)
• A small amount of steel or aluminum screening
• A short-length section of clear tubing for an enclosure of the active element.
• A medium-length section of general tubing, such as a vacuum hose.
• A blower -- this part depends on your main use for your ozone machine. A small cooling fan would be ideal for most cases. If you're ozonating water, you probably want to use an air pump that is suited to pumping gas into water. Or if you if you want real high performance, you could probably use a vacuum cleaner motor! You'll preferably want something that takes AC mains power, so you can splice it in with the power supply for your transformer.
• A soldering iron and solder
• Electrical tape.
• Duct tape.
Step 1: Cut two strips of the metal screening. The width of strips should be a little less than the length of the guitar slide. The length of the strips should be 4 or 5 inches. Each strip should also be cut so as to have a small tab sticking out by an inch or so, along the axis of the width, which will be used as the soldering point for the wire from the transformer.
Step 2: Wrap the strips into springy cylinders. Shape them so that one will snuggly fit into the inside of the guitar slide, and the other will snuggly fit over the outside. Solder the leads from the transformer to the tabs of the strips, and cover with electrical tape. You might want to add some solder to the outer cylinder to help it keep its shape. It should now look like figure 1.
Step 3: Insert the inner cylinder into one end of the guitar slide, and slide the outer cylinder over the opposite end. Wherever the two overlap is where the reaction will take place. It's important to prevent any overlapping section from approaching either edge of the slide, as that would allow the electrical arc to jump the gap. Similarly, look for and trim off any stray wires that might serve as a path for wayward electrons. It should now look like figure 2
Step 4: Plug in the transformer, and see if it works! If so, should see a blue glow and a quiet crackling or buzzing noise (see figure 3). If you are not getting a short circuit and not getting a glow, you might have too much surface area for the voltage being supplied by your transformer. In that case, try adjusting the amount of section overlap, by sliding the cylinders out away from the tube (figure 4) or back in (preferably after shutting off the power). Ideal results are the maximum overlapping surface area that produces a clearly visible plasma effect.
Step 5: Place the device inside the clear tube enclosure. You will have to slide out one of the cylinder elements to do this, and then replace it. Once the cylinder elements are back in their proper positions, secure each cylinder edge to the glass slide edge with electrical tape to keep them there. Only tape outside the area of reaction (the overlap area). Otherwise the tape is likely to burn, melt, or get otherwise involved in the plasma reaction.
Step 6: Secure the inner device in place within the outer enclosure using electrical tape as necessary. If you can secure it so the outer cylinder doesn't contact the outer tube, so much the better, but in my experience it is not a problem for it to touch. The metal gets warm, but as you can see in figure 5, it's the glass that bears the brunt of the abuse from the electrons. You might want to cut notches in your outer enclosure for the transformer leads to exit out of. You should now have something like figure 6.
Step 7: Using duct tape, attach your tubing or vacuum hose pieces to either end of the enclosure, allowing the transformer wires to come out through the duct taped seal. Then attach your blower to one end. Preferably it's AC powered, so you can splice its power cord with the transformer's so you can have a common power cord. Because of the high voltages involved, it's probably a good idea to connect the ground wire of the power cord to the blower chassis, to prevent it from accumulating charges. My completed project looks like figure 7, but depending on your application, you may not want to use as much tubing length, and your blower will preferably be less bulky than mine.
Step 8: Go ozonate something! Take care to prevent humans, pets and livestock from inhaling of high concentrations of ozone.
ANECDOTAL SAFETY CONSIDERATIONS
In my experience, a room can be safely ozonated at high levels by leaving it unoccupied and its doors closed while running the ozone machine for an extended period. After turning it off, leave the room unoccupied until the smell of ozone in the room is no longer strong. It is to be expected that you will be able to smell the ozone in other parts of the house. (If you are married, and you can't smell it in other parts of the house, it is to be expected that your wife will be able to smell it in other parts of the house -- It's possible your wife might not like the ozone machine until you do something substancially useful with it.)
The ozone machine should NOT be run for extended periods in an occupied room. If you are in the same room as your operating ozone machine, be aware of any sensations of irritation or tickling to your throat or lungs. If you experience this, you have inhaled too much ozone! Go outside immediately! If you fail to do so, you may soon reach a threshold where it will suddenly become difficult to breath, and fresh air will not immediately resolve the situation. This is a very unpleasant sensation. ...er, I mean I would imagine it to be.
The other safety consideration is in regard to fire. I think the best way to mitigate this risk is to stress-test the machine -- that is, run the machine for, say, 3-4 hours under controlled conditions. If that goes without incident, it could be presumed safe for shorter periods of time as well. Also, every time you start it up, visually inspect the active mechanism to make sure there is no damage, and no movement of parts that might produce a short. Make sure that there is no coronal discharge too close to the edge of the glass. If attempting any of the every-day applications below, careful thought should be given for how to safe-guard the device in this regard.