Specifications

CONSTRUCTION
PORTABLE OZONE GENERATOR
T
his article is dedicated to the
good health of EFY readers in
the year 2000 and beyond. It de-
scribes an ozone generator for portable
(and portable1) use.
Ozone gas is now-a-days used for
treatment of drinking water, disinfec-
tion, and air-purification. What one re-
quires is a small and handy unit to be
plugged into mains to get ozonated air
at suitable pressure flowing out from a
tube It can then be let into environment
or bubbled through water or any other
polluted liquid. But the gadget must be
completely safe to work with.
Ozone generators invariably make
use of a discharge tube to which a high
electric field is applied so as to break
down the oxygen present in the air. This
phenomenon occurs at or near a field
strength of 25 kV/cm, and the resulting
discharge that takes place is known as
corona. The corona has a light bluish
glow. It is in this corona field that oxy-
gen becomes ozone (O3).
Ozone has tendency to revert back to
its original form in about 10-20 minutes,
in the atmosphere. Therefore, it is nec-
essary in any ozone application to gener-
ate ozone as and when requied for use
since it cannot be kept stored the way
chlorine is stored (in cylinders). Chlo-
rine is used in our cit-
ies to disinfect drink-
ing water supply. It is
highly carcinogenic be-
cause when it comes
into contact with rem-
nants of pesticides in
our foodstuff (veg-
etables), it generate
halomethanes, which
are carcinogenic. That is why, ozone is
used today in preference to chlorine.
Complete disinfection of water, in
any impure form, is realised with an
ozone content of 4 mg/litre. Ozone gen-
erator presented here has a capacity of
producing 10 mg/minute of ozone com-
bined with atmospheric air. This unit
can treat five litres of impure water in
just two minutes.
The discharge tube is supplied air
from an air-group, which is built into the
unit. The unit produces ozonated air at a
pressure head of 15-20 cm of water via
its outlet. So the exit tube can be let into
water containers with water up to a level
of 10-15 cm.
Another advantage of this unit is
that it is light in weight (less than a
kilogram) and carries a very simple con-
trol and a microammeter showing the
ozone concentration. It employs a high
voltage of over 5 kV at a high frequency
of 15 kHz to 20 kHz, which would not
cause a lethal shock. Shock voltages are
not cause a lethal shock. Shock voltages
are not dangerous at these high frequen-
cies, while at 50 Hz these high voltages
are quite dangerous.
Commercial ozone generators make
use of mains 50Hz frequency and are
thus very dangerous while assembling.
Extreme care is required to be exercised
by the user while diagnosing any prob-
lem with such apparatus. Ozone genera-
tor at the higher frequencies used here
S.C. DWIVEDI
K PADMANABHAN, S ANANTHI AND KIRIT PATEL
Fig. 2: Schematic Diagram of portable ozone
Fig. 1: Airflow through cylindrical space of discharge tube
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