douglas fur on fri 15 oct 10
I built a converto-kiln this summer-
an 18" elec kiln lined with 1" fiber. The finished dimensions are 15" dia
and 18" tall. I've got two pipe burners coming up through the bottom. The
burners are- burner tube 3/4" pipe about 4" long. I made saw kerfs in one
end to collar in the dia to 5/8"- the constriction is to prevent backfiring
and the little triagnular holes left from the kerfs function nicely as a
flame retention tip. The air bell is a 1 1/2" to 3/4" reducing bell. I've
cut a 3/8" tall horizontal slot most of the way around leaving two 1/4'
webs.
In the 1 1/2" end I put a 1 1/2" to 1/4" bushing. I drilled out the bushin=
g
to 3/8" I used a 4" length of threaded lamp part tubing (its the dia and
thread pitch as 1/8" IPS but is continuous instead of tapered*). I used a
1/8"IPS brass plug with a 3/64" orifice connected with a coupling to one en=
d
of the tube. A lock nut on the coutside of the bushing allows adjusting th=
e
orifice up and down in relationship to the bottom of the burner tube- it
works best with the end of the brass plug flush with the bottom of the air
slot. The tube screws into the gas manifold. The Manifold is attatched to =
a
bar-b-que size propane tank which delivers gas at 0.5 psi. The tank volume
holds enough gas to fire the kiln for about 8hr.s
The question is how come I haven't got past ^3? (on the way to ^5)
This is a cool fact (worth the price of reading this) not many know about
The threaded parts, tubing couplings caps nuts et al, made for electric
lamps are the same size threads as common pipe threads- AKA IPS [iron pipe
size] but as they are continuous threads. They are perfect for a burner set
up where you want to have an air spinner- that disc you can adjust to
control primary air- which uses the fuel pipe which leads to an orifce as
its shaft. My hunch is that its a hold over from the gas light days when
the plumber would have put in pipe for the water, gas light and steam heat.
DRB
Seola
more to follow under "manifold" subject line
John Post on fri 15 oct 10
> The question is how come I haven't got past ^3? (on the way to ^5)
I have seen electric conversion kilns stall because the exit flue is
not large enough.
A simple way to find out if this is your problem, is to open the lid
of the kiln just a crack when you are at the point where you normally
stall.
You can often hear the burners sound as if they are increasing in
power if the root of your stalling problem is related to an undersized
flue.
John Post
Sterling Heights, Michigan
http://www.johnpost.us
>
William & Susan Schran User on fri 15 oct 10
On 10/15/10 2:54 PM, "douglas fur" <23drb50@GMAIL.COM> wrote:
> The question is how come I haven't got past ^3? (on the way to ^5)
Good description of kiln size and making of burners, but no mention of the
flue opening or shelf placement. You did cut an exit flue, didn't you? ;^)
How about gas pressure? What's the highest pressure reading? May be to
little or even too much.
Also need to leave a bit of room at bottom between kiln floor and first
shelf for a combustion area. Having first shelf set too low would restrict
heat rise.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Larry Kruzan on sat 16 oct 10
<<<<<<<<<>>>>>>>>>>
I used a
1/8"IPS brass plug with a 3/64" orifice connected with a coupling to one en=
d
of the tube. A lock nut on the coutside of the bushing allows adjusting th=
e
orifice up and down in relationship to the bottom of the burner tube- it
works best with the end of the brass plug flush with the bottom of the air
slot. The tube screws into the gas manifold
<<<<<<<<<< SNIP >>>>>>>>>>>>>>>>>
Hi Douglas,
I suspect that you have two problems that you are dealing with. The first
and the second are gas flow.
I found the one tank did not provide enough gas to the burner. As LP
converts from liquid to gas in the tank the tank and liquid cool, this
cooling slows the conversion to gas, reducing the amount of gas you have
available for burning. Adding a second tank provides twice as much liquid
surface area to convert to gas and overcomes this limiting factor.
The second problem MAY be the regulator that you are using. I use an
adjustable regulator that I got from Ward Burners for this purpose. It
provides much more gas to the burner than a normal grill regulator.
A normal gas grill propane regulator has a limit to how much gas will pass,
this will not let you get to cone 10.
The portable gas kiln I have built is similar to what you have and I can
reach cone 10 with ease, you just need enough gas.
As always YMMV.
Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com
=3D=3D=3D=3D=3D=3D=3D
Email scanned by PC Tools - No viruses or spyware found.
(Email Guard: 7.0.0.18, Virus/Spyware Database: 6.16090)
http://www.pctools.com/
=3D=3D=3D=3D=3D=3D=3D
| |
|
