Make Some Ozone

7/31/2019 Make Some Ozone

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MAKE SOME OZONE.

Ozone is a very interesting gas that is often present in the vicinity of electrical arcing.It has a very distinctive smell and that's why it's name was derived from the Greek

word ozein which means "to smell".

It is a strong airborne oxidant that can be used to freshen the air by destroying

atmospheric germs and odours, care must be taken with the quantity produced though,

since levels that can be smelled are capable of causing irritation to sensitive areas of

the body like the eyes and nose.

Because of it's strong odour destroying properties ozone is often used to freshen the

air in public facilities and can be used to reduce the smell of smoke damage in a

building, or bubbled through water to provide a more effective sterilisation thanchlorine without any residual taste or smell. It's most notorious use must be for the

suppression of the smell from cannabis plants in illegal growing rooms.

It's very easy to make ozone, since it is done by applying Ultra Violet energy or

electrical discharge energy to either pure oxygen, or more commonly just plain air.

The energy of the UV or arc causes the two atoms of a molecule of oxygen to

separate, and some recombine temporarily in an unstable three atom molecule of

ozone. The third oxygen atom is quickly donated to anything in the vicinity and

oxidises it in the process. Ozone must be made on demand since it cannot easily be

stored.Here are three approaches to making ozone. The first is a simple low level ozone

maker which is ideal as an air freshner while the second is a UV technique. The third

is a planar plasma technique which can produce a lot of ozone.


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Here's a simple unit for creating low levels of ozone on a continuous basis. It's a very

reliable design and has a few rather unique features. The hand in front of the unit is to

indicate it's size and also indicate that quite a strong electronic draught comes from

the front despite the unit having no moving parts!

Here's how it works... A voltage multiplier like the one on the ioniser page is used to

apply a high negative voltage to a needle. Unlike an ioniser which projects ions

straight into the air, this unit is encouraged to emit ions by having a short metal tube at

the opposite potential placed in front of the needle. This causes a strong corona to

appear at the needle tip, and the high volume of ion discharge over to the tube causes

a strong airflow which carries ozone from the needle tip corona out into the room.

The schematic above shows a couple of resistors between the power supply and the

tube. This is to avoid having the tube at mains potential when the circuit is used with amains powered voltage multiplier.


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This unit was bodged together experimentally, and uses a 30 stage 220n mains

powered (240V) voltage multiplier which has been split into sections to save space.

There's more information on these multipliers on the ioniser page.

The connections between the sections of voltage multiplier are just thin hookup wire,since the potential between stages is relatively low at a few hundred volts. The output

goes via the usual safety resistor/s and also passes through a neon and capacitor based

current flow indicator as used on the ioniser page. The final output is on three needles

pointing at three short tubes made from brass eyelets soldered to self adhesive copper

tape. The tubes are all conected to mains neutral via a few safety resistors.

Here's a close-up view showing the emitter and tube, and also the neon output level

indicator.


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This is an experimental ozone generator based on a mercury discharge lamp. It has a

fan and uses a resistor to limit the current through a quartz tube mercury discarge

lamp which has been removed from a commercial mercury vapour lamp.

It must be stressed that without the glass envelope of the lamp to act as a filter, thequartz tube passes the more harmful ultraviolet wavelengths which CAN CAUSE

EYE DAMAGE and sunburn. Even though the tube in this design was operated at a

very low current, it was still shielded completely in a metal case to prevent anyone

from staring at the lamp and suffering possible eye damage.

The design certainly produced ozone, but I think I'm under-running the lamp to the

point that it has blackened inside quite severely, although running it at a higher

current briefly might help clear the blackening. I might re-visit this project at some

point.

To help the mercury tube strike, a resistor of about 220K should be wired between one

end of the tube and the little auxilliary electrode at the other end. The tube MUST be

in series with a resistor or choke to limit the current through it.


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Here's the really violent way to make tons of ozone. It's basically a thin piece of glass

with metal mesh stuck to both sides. When about 5kV is applied to the meshes, a largearea corona discharge occurs between the mesh and glass on both sides. This makes a

LOT of ozone.

The mesh is tacked to the glass at regular intervals by squirting hot melt glue directly

through it and onto the glass. Silicon would probably stick better and withstand the

oxidising effect of the ozone, but hot melt is much easier.

The mesh must be cut smaller than the glass to avoid arcing at the edges, and it must

be tacked frequently while leaving a small gap between the mesh and glass to allowairflow through the corona. If it is tacked too far apart it will buzz noisily when

powered up.


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The neon transformer wires are attached directly to the metal mesh which should be

stainless steel to avoid oxidation problems. I used copper mesh since it was freely

available in the prop-shop where it is used as a malleable form for clay structures.

I've really gone to town on tacking the wires down with hot melt glue, although inhindsight if I had attached the wires centrally along one edge, the whole panel could

have been suspended from the ceiling by it's wires. I suppose silicon would be better

for this bit, since it would definitely adhere to the glass better for hanging.

The unit makes a soft FRRRRRR! noise while powered, and a very faint corona

discharge is visible in a very dark room. The current involved is very low with an A4

sized panel passing about 1mA at 5kV.

The reason for the glass is as a barrier between the mesh electrodes. If it wasn't there

they would just arc across noisily, however with the glass in place the whole

arrangement turns into an air and glass dielectric capacitor, and the controlled chargetransfer across the air (corona) splits the oxygen into ozone.

Here's a commercial British ozone generator that is often found in public restrooms as

an air sanitizer.


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The fact that it uses no chemicals, and genuinely destroys airborn bacteria and odours

means that it is a cost effective alternative to traditional air freshener sprays and gels.

Just fit and forget.

The round electrodes are very smart and robust, and the tubular arrangement gives the

mesh rigidity which reduces noise to a faint fizz.

The transformer at the right hand side is a continuously rated 5kV boiler ignition

transformer with one end of the 5kV secondary grounded internally. It's HT output is

connected to the corona tubes by terminals at their ends.

The electrodes couldn't be simpler. A scroll of stainless steel mesh is pushed into a

Pyrex test-tube where it unfurls against the walls and a lug on the end makes

connection to the circuit through a nut and bolt through the screw-on lid.A stainless steel mesh tube on the outside of the test-tube acts as the other mesh

electrode and is connected to ground via the terry clip mountings that hold the

assembly in place.

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Make Some Ozone