Dan or Janice on wed 16 feb 00
I have a 5.25 ft3 electric kiln which I am trying to retrofit as a gas
kiln. I have never fired with gas before. I wonder if anyone can offer
advice about whether this is feasible? I fire to cone 01. The kiln has
10 inches of softbrick insulation in a steel case, set up 2 feet off the
floor and 2 small side vents (why? who knows-I inherited this and it
never was operational) which I intend to cut out 1 port for the burner
and 1 for the flue creating a downdraft circulation. I have purchased a
ransome venturi burner which I intend to fuel with propane. My questions
are: is the firing chamber too small for firing with this type of
burner? Will it heat too quickly? Second, it is my hope to install this
in a garage studio that I am in the process of constructing. Since the
kiln has no chimney, can I use regular stove pipe double walled chimney
if the rating is below the temperature of cone 01? Or is some other
chimney material required. I called my local supplier (Bailey) and they
would not sell chimney for another kiln. Finally, in reading the various
construction books I've found, none specify chimney height or diameter.
Would 6 inch diameter work for a one-burner system with a 4.5 inch
burner port? Many thanks to anyone who can help or point me in the right
direction.
ferenc jakab on thu 17 feb 00
Dan or Janice,
I've just done this with an electric kiln. How big is your burner? I suspect
it might be too large for 5 cubic '. I'm using 2 x 1.5" burners with pilot
light ignition in a 13 cubic ' kiln. The idea is that I turn on the second
burner as I need it, usually at about 400 deg C. I steam on the pilots up to
100 deg C, lighting first one and then the other as the rate of climb levels
out over about 24 hours. The flue is double fire brick standing on a steel
frame. The exit from the kiln is 4"x2" into a 12"x12"x12"chamber that then
exits into a brick chimney to about 6' and then a 4"diameter stainless
steel pipe to 3.4 metres and then a canopy with a 4" flue extending to 5.5
metres.
I cannot help with U.S. specific materials.
Feri.
James L Bowen on thu 17 feb 00
-------------------
Try a needle valve to turn up the gas, with a 0-30 lb guage between the =
valve
and burner to provide feedback you can use to chart your firing. Needle =
valves
provide very precise adjustments. We turned a 1027 scutt into an updraft =
kiln
and our results were a three cone difference top to bottom ( probably to be
expected on an updraft kiln) and to rapid a cooling. Next time we fire it we
will put cone 8 glazes on the bottom and cone 9-10 in the middle and cone 11=
on
top and then fire down slowly to provide a longer cooling cycle.
James L Bowen on thu 17 feb 00
-------------------
Actually our updraft kiln fired hotter on the bottom than the top. Cone 11 =
on
the bottom and 8 on the top shelf. Sorry about the error.
Norman van der Sluys on sat 19 feb 00
Don't settle for a 3 cone difference in an updraft kiln! Contrary to what you ha
read here on Clayart and elsewhere, updraft kilns are not necessarily uneven
firing. Two points I would try include adjusting the primary air for optimum
performance - blue flame but not sitting above the burner tube, and adjust the
outlet flue. You probably also need a baffle shelf below the flue. I also have
more even results when I don't try to fire too fast.
Norman van der Sluys
James L Bowen wrote:
> ----------------------------Original message----------------------------
> -------------------
> Actually our updraft kiln fired hotter on the bottom than the top. Cone 11 on
> the bottom and 8 on the top shelf. Sorry about the error.
Jo Gallegos on sat 19 feb 00
Hey, I just had a great 1st firing in a trashcan raku, today produced 9 for
us and 1 for the raku gods, just thought i share the great news. (next i'll
figure how to use mail servers. lol jo
| |
|
