David Hendley on thu 20 jun 02
This is funny that there are two questions in a row about
kiln exhaust and tree branches.
I have ten years experience with firing my wood-fired kiln
under an oak tree.
I don't think there's any kind of formula to measure the temperature
once the heat leaves a kiln. Where I am, anyway, wind plays a
big role in what happens to flame, smoke, and heat once it
exits the chimney, and this is not known as a windy area.
Anyway, the tree next to my kin is huge, three feet in diameter,
and there is a branch, probably 15 inches in diameter right
over the chimney, about 15 feet above it. I installed a heat shield
on the branch. It is a piece of galvanized roofing, 2 feet wide
and 8 feet long, loosely held a few inches from the bottom of
the branch by wires looped over the top of the branch.
This worked fine. No damage to the branch after 8 years of firing,
and my kiln can send actual flames 3 or 4 feet out the top of the
chimney.
Then, a few years ago, one of the wires broke, and I neglected to
fix it for a while.
I caught the branch on fire! Just smoldering, really.
It was not a danger, as I just regularly wet down the branch with
a garden hose (always near-by on firing day) for the rest of the
firing, but it demonstrated what a good job the heat shield had done
all those years.
The shield is back in place, and the branch still shows no damage.
So, compared to my situation, with the fire belching monster,
a raku kiln and a gas kiln seem pretty tame. I don't think you could
possibly damage a branch 12 -15 feet behind the kiln.
A pine tree branch directly above a kiln sounds dangerous,
but if it is 'way up' I think there would be enough wind to diffuse
the heat even on a calm day, so the branch would not be directly
assaulted. I would suggest a heat shield, just to be safe. Pine
needle can ignite pretty easily.
Or, you might just cut off the lower branches.
If my branch weren't as big as a large tree itself and hanging over the
shop, I would have simply pruned it.
As for smoke from reduction damaging a tree, I haven't seen
any evidence of it, and again, my wood kiln has been putting out lots
more smoke than a gas kiln for 10 years.
I do cease firing my kiln when the county announces a 'burning
ban', when it is extra hot and dry. In my area this usually happens
for a couple of weeks every summer.
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com
----- Original Message -----
I have a new 10 cubic ft downdraft gas kiln that I have fired several times
since spring. My problem is that there is a black oak tree on an easement
behind it that I'm sure my neighbors will not allow me to cut down. When I
put the kiln in reduction, one of the branches is about 12 to 15 feet behind
it and about 10 feet above ground. The next branch is about a two feet
higher. I fired this last weekend, and the leaves did not flutter or stir
throughout the firing. I also watched many news reports on the many
wildfires in CO and throughout the midwest...pretty scary. Should I shut
down the kiln until fall?
----- Original Message -----
Next question: Does anyone know of any formula
that can be used to measure the temperature of the air
from the point it exits the flue of a gas kiln to any
specific height above the flue? Say three feet, or
ten, or fifty, or a hundred? Olsen gives a temperature
reference in his book, but it only for one set
distance. Any formula would have to include air speed,
current temperature humidity and the like I imagine.
I want to know what the temperature is at the
lower brach of the pine tree which is close to over my
raku kiln. It's way up, but some of the needles are
curling. I live in a pine forest and moving the kiln
is an option but I'm curious anyway. It's fire season
here and it looks like a nasty one, so I have stopped
firing for now.
Steve Mills on sat 22 jun 02
In message , David Hendley writes
>This is funny that there are two questions in a row about
>kiln exhaust and tree branches.
As an addition to David's post; I used to fire my Raku Kiln in the back
yard, it was protected from the elements by a sheet of polythene
approximately 2 feet above it. It never melted, even with 2 to 3 inches
of flame occasionally out of the flue.
--
Steve Mills
Bath
UK
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