PBORIAN on thu 18 apr 02
Hello,
I have a question for those with kiln building experience. I have read in
Olsen's kiln book that one should never position the burners in such a way
that the orifice is above the burner tip. I would like for someone to
explain this principle, and i would also like to know if this would still
apply with propane. Also, would it then be allright to position the burners
with the orifice below the burner tip, with the gas flowing upward. I am
using forced air burners, if that makes any difference.
Any feedback would be greatly appreciated, as this is my first kiln building
project and i want to do it right. Thanks
Paul
Falmouth, ky
Hank Murrow on thu 18 apr 02
>Hello,
>I have a question for those with kiln building experience. I have read in
>Olsen's kiln book that one should never position the burners in such a way
>that the orifice is above the burner tip. I would like for someone to
>explain this principle, and i would also like to know if this would still
>apply with propane. Also, would it then be allright to position the
burners
>with the orifice below the burner tip, with the gas flowing upward. I am
>using forced air burners, if that makes any difference.
>Any feedback would be greatly appreciated, as this is my first kiln
building
>project and i want to do it right. Thanks
>Paul
>Falmouth, ky
Dear Paul;
Olsen was probably thinking that Natural gas is lighter than
air, so an orifice down location should have some benefit. With
propane, the fuel is heavier than air, and if Fred is right, the
reverse logic would apply.
Best, Hank
vince pitelka on thu 18 apr 02
> I have a question for those with kiln building experience. I have read in
> Olsen's kiln book that one should never position the burners in such a way
> that the orifice is above the burner tip. I would like for someone to
> explain this principle, and i would also like to know if this would still
> apply with propane. Also, would it then be allright to position the
burners
> with the orifice below the burner tip, with the gas flowing upward. I am
> using forced air burners, if that makes any difference.
> Any feedback would be greatly appreciated, as this is my first kiln
building
> project and i want to do it right. Thanks
Paul -
This was discussed several weeks ago on Clayart. If your burners are
functioning properly, there is no problem with the orifices above or below
the burner tips. Positioning them below the burner tips is very common, as
in most natural draft updraft kilns. Plus, if the burners stick straight
out from the kiln it takes up a hell of a lot of space, and that is the main
reason many people put a bend just before the burner tip, so that most of
the burner sticks downwards.
It is fairly rare to find a kiln with the orifice above the burner tip, but
I have seen it done many times over the years, and have never heard of
anyone having a problem with it. I do not know where this caution came from
.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Marcia Selsor on fri 19 apr 02
Dear paul and Vince
I had two humongous venturi burners with elbows bending up putting the
orifice about two feet above the burner tip. These had been selected by
the facility maintenance people for the kilns about 22 years ago without
regard for my input. Anyway, they worked fine. Too big for the kilns but
we figured out how to fire with them over the years. I had manufacturers
mauals for the Ransome Venturi burners which showed them installed as we
had them..elbows and extending up to the orifice. Huge burners.
Best regards,
marcia in Montana
(professor emerita from MSU-Billings)
vince pitelka wrote:
>
> >
> Paul -
> This was discussed several weeks ago on Clayart. If your burners are
> functioning properly, there is no problem with the orifices above or below
> the burner tips. Positioning them below the burner tips is very common,
as
> in most natural draft updraft kilns. Plus, if the burners stick straight
> out from the kiln it takes up a hell of a lot of space, and that is the
main
> reason many people put a bend just before the burner tip, so that most of
> the burner sticks downwards.
>
> It is fairly rare to find a kiln with the orifice above the burner tip,
but
> I have seen it done many times over the years, and have never heard of
> anyone having a problem with it. I do not know where this caution came
from
> .
> Good luck -
> - Vince
>
> Vince Pitelka
> Appalachian Center for Crafts
> Tennessee Technological University
> 1560 Craft Center Drive, Smithville TN 37166
> Home - vpitelka@dtccom.net
> 615/597-5376
> Work - wpitelka@tntech.edu
> 615/597-6801 ext. 111, fax 615/597-6803
> http://www.craftcenter.tntech.edu/
>
>
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--
Marcia Selsor
selsor@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/Tuscany2002.html
John Baymore on sun 21 apr 02
It is fairly rare to find a kiln with the orifice above the burner tip, b=
ut
I have seen it done many times over the years, and have never heard of
anyone having a problem with it. I do not know where this caution came
from
Vince and all,
My guess, and that is all it is .....a guess......... is that it came fr=
om
when folks were making home-made burners like the old standby inspirating=
"Alfred" pipe burners out of standard black iron pipe fittings (made my
share of them too ). Because they were pretty "loose" in
construction........ some worked better than others. So with all the
variations of "retention heads" made by using pipe caps with drilled hole=
s,
step down bushings centered in the mixing tube, and all those kinds of
"cobbled up" things...... it was possible that the outflow of gases at th=
e
nozzle end could sometimes be a tad LESS than the input at the orifice an=
d
air intake end . So having the retention head end higher than the
orifice end gave a little "assist" to the natural gas actually making it
out the nozzle..... and vica versa for propane .
Other than that......... can't see why it would make a difference on a
properly designed system.
Best,
..............................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752 (s)
800-900-1110 (s)
JohnBaymore.com
JBaymore@compuserve.com
"DATES SET: Earth, Water, and Fire Noborigama Woodfiring Workshop Augu=
st
16-25, 2002"
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