Nils Lou on sat 23 jan 10
I promised sometime ago to let everyone know about
a project I started a year ago to develop a relatively
inexpensive probe that would produce digital data on
atmosphere and temperature. The prototype has been used in
22 C10, reduction firings at Linfield College in an Olsen
updraft and MFT car kiln. Typical firing is seven hours. I call it=3D20
the O2Probe TM. It indicates oxygen levels exactly like the=3D20
expensive probes that use R-type thermocouples and platinum
conduits. They are expensive because platinum is about $1440
an ounce and they use 45 inches of 24 gauge wire at about $14/inch.
The O2Probe TM has no platinum and uses a K-type thermocouple
coated with a proprietary film protecting it from reduction
atmospheres. Atmosphere is read as DC voltage rangeing from
.000, neutral/oxidising to .35, medium reduction. Temperature is
read DIRECTLY in Celsius up to 1300=3DB0C. No need to go to a chart
to get temp. as is the case with the plat. probes. The price
will be around $500, about half the cost. I can make them on
custom order if any one is interested. If there is enough interest
production costs will lower the price. Right now the sensor is the
biggest cost. It is the exact same one used in the expensive probes.
And I am still checking out the best meter. It might possibly be
seen at NCECA at one of the commercial venues.=3D20
nils lou, professor of art
http://nilslou.blogspot.com
www.tinyurl.com/bpc5nm
503.883.2274
"Play is the essence of creativity", and
"What is not brought forward into consciousness....
we later call Fate", Carl Jung
Steve Slatin on sun 24 jan 10
James -- This may be a foolish thought, but
why do you need to have a calibrated
O2 reading? What you want to know during the
process of a firing is whether you're getting
reduction or not, and if the sensor shows you
when you're getting no reduction (an easy
'event' to chart) then you can view the change
as an indication of how much reduction you're
getting.
Then the experience of a few firings will show
you how significant the different MV results
are ... and you can replicate them easily.
Just my two sou ...
Steve Slatin --=3D20
--- On Sun, 1/24/10, James Freeman wrote:
> From: James Freeman
> Subject: Re: oxygen probe development
> To: Clayart@LSV.CERAMICS.ORG
> Date: Sunday, January 24, 2010, 10:14 AM
> John..
>=3D20
> Here is info on an automotive oxygen sensor adapted to kiln
> use:
>=3D20
> http://members.optusnet.com.au/~rogergraham/the_kiln_exhaust_sniffer.pdf
>=3D20
> I also recall reading an article on the same issue some
> years ago, probably
> in an old CM from 10 or 15 years past.
>=3D20
> The main problem seems to be that you need access to a real
> oxy probe in
> order to map the millivolt output of the auto oxygen sensor
> into a
> meaningful oxygen reading.=3DA0 Without such, all you know
> is that you went
> from, say, 600 to 800 millivolts.=3DA0 That tells you only
> about relative oxygen
> level, but tells you nothing about the absolute amount of
> oxygen in the kiln
> atmosphere.
>=3D20
> Take care.
>=3D20
> ...James
>=3D20
> James Freeman
>=3D20
> "All I say is by way of discourse, and nothing by way of
> advice.=3DA0 I should
> not speak so boldly if it were my due to be believed."
> -Michel de Montaigne
>=3D20
> http://www.jamesfreemanstudio.com
> http://www.flickr.com/photos/jamesfreemanstudio/
> http://www.jamesfreemanstudio.com/clayart/
>=3D20
>=3D20
>=3D20
> On Sun, Jan 24, 2010 at 12:19 PM, John Rodgers
> wrote:
>=3D20
> > Nils,
> >
> > You have probably already considered it, but what
> would be the prospect
> > of using an automotive type Oxygen sensor for the
> probe, mounted
> > somewhere in the exhaust stream of a fuel fired
> kiln?=3DA0 You have probably
> > already considered it, and=3DA0 I'm not long on
> experience with such kilns
> > but I just had to ask.
> >
> >
> =3D0A=3D0A=3D0A
KATHI LESUEUR on sun 24 jan 10
John,
That's the principal of using the Bacarach CO2 analyzer. It's =3D20
designed for testing combustion on an oil furnace, but it can be used =3D20=
=3D
on a kiln with the proper quartz cooling tube.
KATHI LESUEUR
http://www.lesueurclaywork.com
On Jan 24, 2010, at 12:19 PM, John Rodgers wrote:
> Nils,
>
> You have probably already considered it, but what would be the =3D20
> prospect
> of using an automotive type Oxygen sensor for the probe, mounted
> somewhere in the exhaust stream of a fuel fired kiln? You have =3D20
> probably
> already considered it, and I'm not long on experience with such kilns
> but I just had to ask.
>
> Thanks
>
> John Rodgers
> Clayartist and Moldmaker
> 88'GL VW Bus Driver
> Chelsea, AL
> Http://www.moldhaus.com
>
>
>
> Nils Lou wrote:
>> I promised sometime ago to let everyone know about
>> a project I started a year ago to develop a relatively
>> inexpensive probe that would produce digital data on
>> atmosphere and temperature. The prototype has been used in
>> 22 C10, reduction firings at Linfield College in an Olsen
>> updraft and MFT car kiln. Typical firing is seven hours. I call it
>> the O2Probe TM. It indicates oxygen levels exactly like the
>> expensive probes that use R-type thermocouples and platinum
>> conduits. They are expensive because platinum is about $1440
>> an ounce and they use 45 inches of 24 gauge wire at about $14/inch.
>>
>> The O2Probe TM has no platinum and uses a K-type thermocouple
>> coated with a proprietary film protecting it from reduction
>> atmospheres. Atmosphere is read as DC voltage rangeing from
>> .000, neutral/oxidising to .35, medium reduction. Temperature is
>> read DIRECTLY in Celsius up to 1300=3DB0C. No need to go to a chart
>> to get temp. as is the case with the plat. probes. The price
>> will be around $500, about half the cost. I can make them on
>> custom order if any one is interested. If there is enough interest
>> production costs will lower the price. Right now the sensor is the
>> biggest cost. It is the exact same one used in the expensive probes.
>> And I am still checking out the best meter. It might possibly be
>> seen at NCECA at one of the commercial venues.
>>
>> nils lou, professor of art
>> http://nilslou.blogspot.com
>> www.tinyurl.com/bpc5nm
>> 503.883.2274
>> "Play is the essence of creativity", and
>> "What is not brought forward into consciousness....
>> we later call Fate", Carl Jung
>>
>>
>>
>
John Rodgers on sun 24 jan 10
Nils,
You have probably already considered it, but what would be the prospect
of using an automotive type Oxygen sensor for the probe, mounted
somewhere in the exhaust stream of a fuel fired kiln? You have probably
already considered it, and I'm not long on experience with such kilns
but I just had to ask.
Thanks
John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com
Nils Lou wrote:
> I promised sometime ago to let everyone know about
> a project I started a year ago to develop a relatively
> inexpensive probe that would produce digital data on
> atmosphere and temperature. The prototype has been used in
> 22 C10, reduction firings at Linfield College in an Olsen
> updraft and MFT car kiln. Typical firing is seven hours. I call it
> the O2Probe TM. It indicates oxygen levels exactly like the
> expensive probes that use R-type thermocouples and platinum
> conduits. They are expensive because platinum is about $1440
> an ounce and they use 45 inches of 24 gauge wire at about $14/inch.
>
> The O2Probe TM has no platinum and uses a K-type thermocouple
> coated with a proprietary film protecting it from reduction
> atmospheres. Atmosphere is read as DC voltage rangeing from
> .000, neutral/oxidising to .35, medium reduction. Temperature is
> read DIRECTLY in Celsius up to 1300=B0C. No need to go to a chart
> to get temp. as is the case with the plat. probes. The price
> will be around $500, about half the cost. I can make them on
> custom order if any one is interested. If there is enough interest
> production costs will lower the price. Right now the sensor is the
> biggest cost. It is the exact same one used in the expensive probes.
> And I am still checking out the best meter. It might possibly be
> seen at NCECA at one of the commercial venues.
>
> nils lou, professor of art
> http://nilslou.blogspot.com
> www.tinyurl.com/bpc5nm
> 503.883.2274
> "Play is the essence of creativity", and
> "What is not brought forward into consciousness....
> we later call Fate", Carl Jung
>
>
>
James Freeman on sun 24 jan 10
John..
Here is info on an automotive oxygen sensor adapted to kiln use:
http://members.optusnet.com.au/~rogergraham/the_kiln_exhaust_sniffer.pdf
I also recall reading an article on the same issue some years ago, probably
in an old CM from 10 or 15 years past.
The main problem seems to be that you need access to a real oxy probe in
order to map the millivolt output of the auto oxygen sensor into a
meaningful oxygen reading. Without such, all you know is that you went
from, say, 600 to 800 millivolts. That tells you only about relative oxyge=
n
level, but tells you nothing about the absolute amount of oxygen in the kil=
n
atmosphere.
Take care.
...James
James Freeman
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/clayart/
On Sun, Jan 24, 2010 at 12:19 PM, John Rodgers wrote:
> Nils,
>
> You have probably already considered it, but what would be the prospect
> of using an automotive type Oxygen sensor for the probe, mounted
> somewhere in the exhaust stream of a fuel fired kiln? You have probably
> already considered it, and I'm not long on experience with such kilns
> but I just had to ask.
>
>
Larry Kruzan on sun 24 jan 10
************
lower the price. Right now the sensor is the
biggest cost. It is the exact same one used in the expensive probes.
And I am still checking out the best meter. It might possibly be
seen at NCECA at one of the commercial venues.
nils lou, professor of art
*****************
Hi Nils,
Yahooooo and at-a-boy!!!
For those of us who own the other meters, will it be possible to us those
and just buy the sensor?
Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com
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Database version: 6.14090
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James Freeman on mon 25 jan 10
Steve...
Sounds reasonable to me, but how do you know when you have neutral
conditions in the kiln in order to say "this millivoltage reading
corresponds to neutral"? Kind of like using a worn out thermocouple;
knowing from experience (or cones) that when the meter reads temperature X,
you are really closer to temperature Y. Much easier with a calibrated
pyrometer, where one could simply read an accurate temperature directly, bu=
t
certainly doable (after a fashion) the other way. I also recall reading
somewhere that it is physically impossible to obtain a reference neutral, o=
r
"stochiometric" flame except under laboratory conditions. I believe the
calibration process employs gasses of known makeup.
Anyway, I don't have nor use an oxygen analyzer, as I no longer fire with
gas (too much trouble hauling pots to the college). I was merely offering =
a
link from my files (from previous research when I was interested in such
things) in answer to John R's question about using an automotive lambda
sensor in a kiln. A chart in the article shows that though the voltage
output from the lambda sensor has the same shape curve as does the oxyprobe=
,
the absolute voltage readings are different, due, I believe, to differences
in sensor construction and makeup. Here is a link to an article describing
some of the different types of oxygen sensors:
http://www2.emersonprocess.com/siteadmincenter/PM%20Rosemount%20Analytical%=
20Documents/Gas_Article_X-STREAM_O2_200804.pdf
A kindly clayart member sent me a link to another article which I believe
states that if one knows the type of oxygen sensor, then one could merely
look up in a chart what millivolt reading corresponds to what oxygen level,
but I have not yet read it. If this is the case then life gets much
simpler, but it leaves one wondering just what service the calibration
companies are providing.
If I do build a gas kiln, I will simply purchase Nils' new O2Probe and be
done with it. Not worth reinventing the wheel for $500.
A question for Nils, if he is reading this: If your meter only goes to
medium reduction (.35), how does one use it to obtain, say, copper reds,
which I recall reading need heavier reduction in the range of .60-.70?
All the best.
...James
James Freeman
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/clayart/
On Sun, Jan 24, 2010 at 10:54 PM, Steve Slatin wrot=
e:
> James -- This may be a foolish thought, but
> why do you need to have a calibrated
> O2 reading? What you want to know during the
> process of a firing is whether you're getting
> reduction or not, and if the sensor shows you
> when you're getting no reduction (an easy
> 'event' to chart) then you can view the change
> as an indication of how much reduction you're
> getting.
>
> Then the experience of a few firings will show
> you how significant the different MV results
> are ... and you can replicate them easily.
>
> Just my two sou ...
>
>
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