Date: Fri, 5 Nov 2004 12:22:55 -0600
Reply-To: John Rodgers <inua@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <inua@CHARTER.NET>
Subject: Re: Drop in gas mileage update 2
In-Reply-To: <000a01c4c35d$2ebbf020$2fe43f40@korky>
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Interesting things about these O2 sensors.
Potters have discovered the application of the automotive O2 sensor to
the pottery business.
In certain pottery operations that use fuel as opposed to electricity to
fire pots in kilns, it is desirable to fire in what is known as
"Reduction", that is, with low oxygen content in the flame. The reduced
oxygen environment forces the fire to seek it's oxygen for combustion
from the clay and glaze in the pots rather than get it from the
combustion air coming into the kiln from outside. The potter controls
this by varying the intake air using the fuel valves and one or more
dampers. The result is some glaze colors that cannot be acquired any
other way, especially reds in high temperature firings. Most times at
high temps reds burn out and are quite ugly, but not in a properly
controlled reduction firing. But the trick is in that proper control.
Enter the Oxygen sensor. Oxygen sensors for kilns work the same way as
O2 sensors for automobiles - as you have described. For kilns they may
be constructed in a more heavy duty way because of the 2000 + degrees at
which they operate. But the principle is the same. But the really big
difference is in the cost. Kiln O2 sensors cost $300 and up. And there
is a meter that goes with it for additional money. The meter gives a
read out that is related to temperature and to oxygen presence. It does
so based on the voltage produced by the sensor.
It is here that the O2 sensor for the automobile has now come into play.
Recently, a potter struggling whith the cost of a Kiln O2 Sensor,
experimented with a an Automotive O2 sensor. He discovered that by
installing the auto O2 sensor in the kiln exhaust just a coulple of
inches outside the kiln, he was able to get a voltage readout that could
be varied by changing the airflow into the kiln. He could relate the
voltage read out to a temperature chart and a chart of atmospheres and
could therefore tell to what degree his kiln atmosphere was in reduction
or oxidation. So he now had control for his reduction firings for his
kiln. By setting the airflow a certain way he could fix the voltage, and
voltage would tell him to what degree of oxidation or reduction his kiln
was in.
This work was a real blessing for potters, because now the control of
the kiln environment can be done much cheaper. Why?? You can buy an auto
O2 sensor for $50, while the standard Kiln O2 sensor is $3-500. And the
auto sensor doesn't seem to be particularly short lived because of this
treatment. It seems to hold up very well.
I'm sure that someone shortly will devise a meter or find a meter that
will allow direct readout of the voltage as an expression of the oxygen
present. It is just a matter of time.
Just thought I would pass this on. I have found it interesting myself,
since not only do I drive a Vanagon which always seems to have O2
issues, but I am a potter as well.
Regards,
John Rodgers
88 GL Driver
Ken Lewis wrote:
>William,
> The O2 sensor kind of acts like a fuel cell(a battery is a good
>analogy). A voltage is produced (1 to 1.5 volts) when there is a difference
>of oxygen levels between the inside of the sensor(the environment air) and
>the outside of the sensor sitting in the exhaust stream . This indicates a
>rich condition or to little O2.When there is O2 in the exhaust (lean), the
>inside and outside of the sensor has less O2 differences and the voltage
>output drops to zero. See: http://neksiwel.20m.com/photo5.html
>
>Ken Lewis
>
>
>
>
