Specifications

CONSTRUCTION
But now this connection is removed and
only the pump is made to work.
The end of the aquarium air-pump,
which produces air under pressure, is
connected by a s short length of tube to
the corked glass tube of the discharge
tube assembly. The other end of the tube
is fixed to another similar polythene tube
of adequate length (say, one metre).
Now, after allowing the air-pump to
work, one must check whether there is
adequate draft of air through the tube
connected to the air-pump, without any
leakage. Any air leakage prior to tube
entry or through the Teflon tape seals,
or through the inner metal tube, can be
easily detected with figers or soap bubble
test. The leaks have to be plugged
and all air that comes out of the pump
should go through the annular gap of the
discharge path and exit through the out-
let tube.
After this check, the meter connec-
tion is made from the board's 1-kilo-ohm
shunt discharge resistor R15, with se-
ries diode D11 and current limiting re-
sistor R16. The meter is fixed, as stated
earlier, to the from small edge of the
box, which also accommodates the LED
and ozone output control potmeter. The
LED is wired along with diode D12, re-
sistor R17, and capacitor C9 as shown in
Fig. 6.
The lid, on the outside, may be pasted
with the warnign label: “DANGER—DO
NOT OPEN WHEN IN USE”.
After the whole assembly is checked
and mains supply is given, one can watch
the meter reading and green LED on the
panel. The glowing LED indicates that
the circuit, along with LOT, is working
and the meter shows that the there is a
discharge. The sound of the air-pump
wil be heard of course, but one can also
hear the hissing corona sound distinctly.
If lights are 'off', a blue glow may also be
seen on watching from the end of the
glass. A smell like that of rotten fish
from the tube indicates presence of ozone.
The meter reading needs calibration now.
Calibration
There are two ways ot do the calibra-
tion. One is by using an ozone gas
analyser, which is an expensive instru-
ment. So, the other method, which is
economical, is described here.
Potassium iodide (KI) solution is con-
verted to iodine gas by ozone. Taken a
known quantity of KI solution and bubble
the ozonated air from ozone generator
through it, for a definite time (one
minute). The free liberated iodine can be
estimated by titration experiment with
thiosulphate. Thus, by knowing how
much iodine has been liberated, one can
find how much ozone has been absorbed
in the solution by quantitative analysis.
This gives the gas output form the tube
in mg/litre. The gas output can be foud
by finding the time taken to replace the
1 litre of water by the bubbling gas.
After estimating the output of the unit,
marks are made on the meter. This is a
prototype marking which can be followed
in other units of similar design.
Usage
The unit can be used where a 230V AC
mains supply outlet is available. The ozone
generated can be let into air or bubbled
through the solution or water being
treated using ceramic diffusers (available
from aquarium equipment shops). The
time rating of this unit is very short. Sine
there is no fan employed for cooling, both
the discharge tube and circuit board tran-
sistor may quickly heat up The tested
rating at ambient temperature of 25o Cis
5 minutes.. This tim is sufficient for all
the applications described below.
Lab note: The circuit could be con-
tinuously kept 'on' with reduced AC in-
put of 120V AC after changing some of
the component values, including LOT,
at EFY Lab. The changed components/
values have been incorporated into the
final circuit shown in Fig. 2. Since higher
AC voltage (greater than 20 kV) was
available, we could increase the separa-
tion between the aluminium and glass
tubes appreciably.
1. Water disinfection. The impure
water can be disinfected by bubbling
ozone through it for a time so that esti-
mated 4 mg/litre is dissolved.
2. Air purification. You can purify
the air of your room by letting out
ozonated air upward into it for five min-
utes, with a fan running.
3. Mosquito repulsion. Same as
above, but please shut the windows soon
after switching 'off' the ozone generator.
This operation is to be done in he morn-
ing to drive away the mosquitoes and in
the early evening at around 5 pm to
prevent them from coming in. The opera-
tion may be repeated at midnight when
malaria mosquitoes normally attack.
4. Bleaching. The stains of ink on
clothes can be bleached by applying ozone
gas. On bubbling ozone into the diluted
ink contained in a test tube, the water
becomes clear within a short time.
5. Pollutant treatment. Ozone in
large quantities can be used for treating
polluted water in industry, along with
bacterial treatment. The BOD (biologi-
cal oxygen demand) can be
brought down to 30 with
ozone only.
6. Mouth washing.
You may ozonate 200 cc of
water and use it for gar-
gling.
7. Vegetable clean.
Only ozonated water
should be used for cleaning
vegetables like cabbage, to-
matoes, and carrot. Chlori-
nated water is harmful.
8. Skin wound heal-
ing. An exposure to the
ozone gas quickly heals
skin wounds and rashes.
You may apply ozonated
olive oil to speed up heal-
ing.
There are may other
uses of ozone which one can
try. The gas should not,
however, be inhaled di-
rectly, continuously.
G
Fig. 8: Photograph of author’s prototype
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