Jane Murray-Smith on sun 7 aug 05
I have been having problems with my pyrometer for my gas kiln. It is the
2nd one, the 1st having done essentially the same thing, which is, to read
the temperature about 200C degrees higher than the cones
read...consequently, before I get to cone 5, the needle is off the
scale....which makes it impossible to use the pyrometer as a guide for a
controlled cooling down.
The thermocouple has only been used for about 10 firings (max), but logic
seems to indicate that it would be the problem, since both pyrometers did
the same thing.
So I will get another thermocouple, but what I am wondering is, can you
reset the pyrometer according to the cones during the firing? The ambient
temperature thing doesn't apply..
Thanks
Jane
URL Krueger on mon 8 aug 05
Jane,
Is your pyrometer digital or analog? Knowing that might
help get you a better answer.
Also, how fast is the temperature rising just before your
pyrometer indicates the temperature at which the cone
should bend? If it's rising too fast then the cone doesn't
have time to absorb the heat energy needed to soften it and
it will lag behind (so will your pots). It's sort of like
taking an ice cube out of your freezer on a hot muggy day.
The ice cube doesn't melt instantly but over time as it
absorbs heat from your drink.
Check out the Orton web site. They list temperatures at
which cones will bend at various rates of temperature
increase. See if your rate of increase is close to what
they specify in their tables.
--
Earl K...
Bothell WA, USA
Edouard Bastarache Inc. on mon 8 aug 05
Jane,
a qualified instrumentation technician should be able to calibrate the
system,
thermocouple, cables and the scale.
Later,
"Ils sont fous ces quebecois"
"They are insane these quebekers"
"Están locos estos quebequeses"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://retrodemonstration.blogspot.com/
http://www.flickr.com/photos/potier/
http://perso.wanadoo.fr/smart2000/index.htm
http://www.digitalfire.com/education/toxicity/
----- Original Message -----
From: "Jane Murray-Smith"
To:
Sent: Sunday, August 07, 2005 8:14 PM
Subject: adjusting pyrometer
>I have been having problems with my pyrometer for my gas kiln. It is the
> 2nd one, the 1st having done essentially the same thing, which is, to read
> the temperature about 200C degrees higher than the cones
> read...consequently, before I get to cone 5, the needle is off the
> scale....which makes it impossible to use the pyrometer as a guide for a
> controlled cooling down.
> The thermocouple has only been used for about 10 firings (max), but logic
> seems to indicate that it would be the problem, since both pyrometers did
> the same thing.
> So I will get another thermocouple, but what I am wondering is, can you
> reset the pyrometer according to the cones during the firing? The ambient
> temperature thing doesn't apply..
> Thanks
> Jane
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
>
Jane Murray-Smith on mon 8 aug 05
Hi Earl,
It's analog. The rise is not too fast. I often have alot of large pieces
in the gas kiln and take it up very slowly to 010, when I start to reduce.
So, do you know if you can adjust the pyrometer when it is firing?
I have emailed the orton site before and got no response.
Thanks, Jane
----- Original Message -----
From: "URL Krueger"
To:
Sent: Monday, August 08, 2005 12:14 AM
Subject: Re: adjusting pyrometer
> Jane,
>
> Is your pyrometer digital or analog? Knowing that might
> help get you a better answer.
>
> Also, how fast is the temperature rising just before your
> pyrometer indicates the temperature at which the cone
> should bend? If it's rising too fast then the cone doesn't
> have time to absorb the heat energy needed to soften it and
> it will lag behind (so will your pots). It's sort of like
> taking an ice cube out of your freezer on a hot muggy day.
> The ice cube doesn't melt instantly but over time as it
> absorbs heat from your drink.
>
> Check out the Orton web site. They list temperatures at
> which cones will bend at various rates of temperature
> increase. See if your rate of increase is close to what
> they specify in their tables.
>
> --
> Earl K...
> Bothell WA, USA
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Fredrick Paget on mon 8 aug 05
>I have been having problems with my pyrometer for my gas kiln. It is the
>2nd one, the 1st having done essentially the same thing, which is, to read
>the temperature about 200C degrees higher than the cones...............
>
>Jane
I suspect that it is because the probe is located in a spot in the
kiln where the flame passes over the probe before mixing into the
atmosphere where the cones are located.
Another possibility is the wrong type of wire on the extension from
the probe to the meter.
This is supposed to be thermocouple extension wire otherwise you get
about four competing thermojunctions in the circuit. Also it must be
hooked up to the correct sides of the probe.
--
From Fred Paget,
Marin County, CA, USA
fredrick@well.com
Charter Member Potters Council
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