Roger Korn on tue 3 aug 04
challenged,
Ken Nowicki wrote:
...How can I calculate the width and length of the slot to be cut, to properly
match the burner port opening for optimum air flow? ...
Ken,
I left my kiln books down in AZ, but I have an updraft raku kiln of
similar dimensions using the Ransom B-1 burner. The exit flue is a round
hole in the lid 4.5" in diameter with a sliding piece of shelf fragment
as a damper, but I have never opened it more than half way, so the
maximum flue area in use is: .5 x pi x (2.25)^2 = 8 sq inches in a
half-round shape. I use a round burner port 1" larger than the burner
tip diameter. The burner tip is positioned 1/4" outside the burner port.
I suggest that a "one-brick hole" (2.5 x 4.5) would be adequate. You
will want a damper to control atmosphere. Regard the prototype as an
experiment to determine proper dimensions, because you are attempting to
control two variables: atmosphere (reduction->oxidation) and temperature
distribution. Use an Oxyprobe to sample both variables and don't be shy
about changing flue dimensions. My kiln is about 1 1/2 cones colder on
the top shelf compared to the rest of the kiln, so the top shelf becomes
a "baffle", placed about 3/4" below the bottom surface of the lid. This
gives even firing through the rest of the kiln, whether I'm doing a
light reduction ^06 raku load or a full reduction ^10 stoneware load.
Hope this data helps.
Roger, up in OR 'til mid Sept.
--
McKay Creek Ceramics
In OR: PO Box 436
North Plains, OR 97133
503-647-5464
In AZ: PO Box 463
Rimrock, AZ 86335
928-567-5699
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