jonathan byler on wed 16 apr 08
I was wondering if having flame present at the spyhole really is an
indication that the kiln is reducing, or is it just showing back
pressure? Flame at the top of the chimney could indicate reduction
also, correct? I have always assumed this to be the case, but I was
curious if it is possible to have flame showing, because of back
pressure, but to not be an actual reduction flame.
thanks,
jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
Randall Moody on thu 17 apr 08
I could be totally wrong on this but I think that flame at the peep is
showing back pressure but not necessarily reduction and the same goes
for flames from the chimbley. :)
--
Randall in Atlanta
On Wed, Apr 16, 2008 at 9:11 PM, jonathan byler wrote:
> I was wondering if having flame present at the spyhole really is an
> indication that the kiln is reducing, or is it just showing back
> pressure? Flame at the top of the chimney could indicate reduction
> also, correct? I have always assumed this to be the case, but I was
> curious if it is possible to have flame showing, because of back
> pressure, but to not be an actual reduction flame.
>
> thanks,
>
> jon
Steve Mills on thu 17 apr 08
If your kiln is natural draught, i.e with a chimney that "draws", yes that's reduction. If it's a forced draught or "blown" kiln, that's back-pressure.
Either way, a air/fuel imbalance in favour of the latter will generally give a reducing atmosphere.
I guage my reduction by flame in the Chimney and at the spy.
A friend of mine who likes a neutral atmosphere guages it with smoke from a small piece of wood (usually Apple 'cos it smells nice) held just under the spy. If the smoke is drawn in, it's "oxadising", if blown away it's reducing, if it goes straight up it's neutral!
He was once asked why he didn't use an oxyprobe. His answer was:"Apple wood is cheaper, and it tells me all I need to know!"
:-)
Steve
Bath
UK
jonathan byler wrote:
I was wondering if having flame present at the spyhole really is an
indication that the kiln is reducing, or is it just showing back
pressure? Flame at the top of the chimney could indicate reduction
also, correct? I have always assumed this to be the case, but I was
curious if it is possible to have flame showing, because of back
pressure, but to not be an actual reduction flame.
thanks,
jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
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Ron Roy on sun 20 apr 08
Hi Jon,
If there was not extra gas (unburned) in the kiln the back pressure would
be invisable. It's the unburned gas combining with the oxygen in the air
outside the kiln that produces the flame.
You should have some at the lowest spy as well.
If you look at the crack where your damper is - if there is reduction in
the kiln you will see flame there as well - because the unburned gas is
combining with oxygen from the air getting in through the crack.
RR
>I was wondering if having flame present at the spyhole really is an
>indication that the kiln is reducing, or is it just showing back
>pressure? Flame at the top of the chimney could indicate reduction
>also, correct? I have always assumed this to be the case, but I was
>curious if it is possible to have flame showing, because of back
>pressure, but to not be an actual reduction flame.
>
>thanks,
>
>jon
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
jonathan byler on mon 21 apr 08
Thanks ron,
that is what I thought, but it is good to have confirmation that ones
thoughts are correct.
the stacks on our kilns end at the top of the arch and are connected
with triple walled stainless pipe. the connection allows for plenty
of air to mix with the flue gases, and there is flame there when the
kiln is in reduction. I gauge to some extent how heavy it is
reducing by the height of that flame.
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Apr 20, 2008, at 4:29 PM, Ron Roy wrote:
> Hi Jon,
>
> If there was not extra gas (unburned) in the kiln the back pressure
> would
> be invisable. It's the unburned gas combining with the oxygen in
> the air
> outside the kiln that produces the flame.
>
> You should have some at the lowest spy as well.
>
> If you look at the crack where your damper is - if there is
> reduction in
> the kiln you will see flame there as well - because the unburned
> gas is
> combining with oxygen from the air getting in through the crack.
>
> RR
>
>> I was wondering if having flame present at the spyhole really is an
>> indication that the kiln is reducing, or is it just showing back
>> pressure? Flame at the top of the chimney could indicate reduction
>> also, correct? I have always assumed this to be the case, but I was
>> curious if it is possible to have flame showing, because of back
>> pressure, but to not be an actual reduction flame.
>>
>> thanks,
>>
>> jon
>
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here: http://
> www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
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