Michael Lancaster on sun 18 dec 05
We [do] use small tanks for firing, and have since the 1990's when we =
moved to New Mexico. There are problems, which have become more =
extensive. The primary problem is gas pressure loss due to cooling. =
Our kiln is 2' x 2' x 3'. Depending on the time of year, we reach temp =
the first time in about 45 minutes. We often start with the largest =
works, so they require 15 mins extra preheat. I do not use a pyrometer =
as they tend to get destroyed, so I rely on my eye - looking for flux, =
but really judging color and keeping it red orange and not too orange. =
Generally we will get 3 -4 pulls from the first 7 gal tank. We then =
change to a second seven gallon tank and get about 6 pulls. For big =
firing days we keep a 5 gallon tank on reserve and can get about 5-6 =
pulls from it. =20
The primary problem occurs when the tank cools because it effectively =
lowers the pressure. I fire a little home made venturi burner at 19psi. =
I have used a weed burner and it is just slightly lower BTU's than the =
one I now use. As the tank cools from gas loss and the pressure lowers =
then I have to change tanks. In the spring I will build a 38" x 38" x =
38" kiln and it will fire with a Ransome B-4. I know I will need a =
larger tank.
There is a new problem with small tanks. The new federal regulation =
requiring the current valves makes it difficult to refill tanks that are =
not at least 1/4 or less. In cool weather I have to change my tanks =
around 1/3. When I take the tanks into the fueling station - it becomes =
difficult to refill them.
Michael Lancaster=20
Studio98B.com
info@studio98B.com=20
www.studio98B.com
Cerrillos, NM 87010
Marcia Selsor on sun 18 dec 05
I don't understand why you are having problems. I* use small BBQ
tanks, but three at a time plumbed in tandem. I refill them after a
workshop or after a few days of firing. My big kiln takes two burners
(Marc Ward"s). I fire mine at 2.5-3 psi you are using 19. Right there
that should say something. My kiln is 2' x 3' x 30" . I have 2 inch
fiber sprayed with ITC.
I use the same firing schedule 45 minute sometimes an hour for my big
slabs. I let it cool a little before loading the next 2 slabs. I try
to keep it at 35-45 minutes for them. I can do ten loads and then
fire my 2 small kilns several time each on another day before I have
to fill up. Maybe you should look into more efficient burners. I
don't see using 19 psi . Sounds like you'd be freezing your tanks.
One thing that cracks me up is the fueling station. They just can't
figure out why all three tankls are exactly the same..every time.
Marcia Selsor in Montana
On Dec 18, 2005, at 12:06 PM, Michael Lancaster wrote:
> We [do] use small tanks for firing, and have since the 1990's when
> we moved to New Mexico. There are problems, which have become more
> extensive. The primary problem is gas pressure loss due to
> cooling. Our kiln is 2' x 2' x 3'. Depending on the time of year,
> we reach temp the first time in about 45 minutes. We often start
> with the largest works, so they require 15 mins extra preheat. I
> do not use a pyrometer as they tend to get destroyed, so I rely on
> my eye - looking for flux, but really judging color and keeping it
> red orange and not too orange. Generally we will get 3 -4 pulls
> from the first 7 gal tank. We then change to a second seven gallon
> tank and get about 6 pulls. For big firing days we keep a 5 gallon
> tank on reserve and can get about 5-6 pulls from it.
> The primary problem occurs when the tank cools because it
> effectively lowers the pressure. I fire a little home made venturi
> burner at 19psi. I have used a weed burner and it is just slightly
> lower BTU's than the one I now use. As the tank cools from gas
> loss and the pressure lowers then I have to change tanks. In the
> spring I will build a 38" x 38" x 38" kiln and it will fire with a
> Ransome B-4. I know I will need a larger tank.
> There is a new problem with small tanks. The new federal
> regulation requiring the current valves makes it difficult to
> refill tanks that are not at least 1/4 or less. In cool weather I
> have to change my tanks around 1/3. When I take the tanks into the
> fueling station - it becomes difficult to refill them.
>
> Michael Lancaster
> Studio98B.com
> info@studio98B.com
> www.studio98B.com
> Cerrillos, NM 87010
>
> ______________________________________________________________________
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>
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>
William & Susan Schran User on sun 18 dec 05
On 12/18/05 2:06 PM, "Michael Lancaster" wrote:
> We [do] use small tanks for firing, and have since the 1990's when we moved to
> New Mexico. There are problems, which have become more extensive.
This has been discussed before, but placing the propane tank in a tub of
water will warm the tank and keep it from freezing. I do this for our raku
firings at school and we can run the tank until it's empty.
I also suspect your using too high a pressure for firing. We use a MR750
venturi burner and the highest pressure we use is 2/3lb.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
Michael Lancaster on tue 27 dec 05
Marcia's idea of tanks in tandem sounds great! I spoke at length with =
Marc Ward and we will soon be taking one of the burners off of our 80 cu =
ft soda kiln. We fire them at 4-5 psi reaching cone 11 +. The high psi =
is because of the small orifice needed for a small venturi. I look =
forward to the change and the quiter burner (ransome B-4). I will =
probably wait till I build a larger kiln 3'x3'x3'.
Michael Lancaster
www.studio98B.com=20
njlancaster@iglide.net
505-474-7564
98B Gold Mine Rd
Cerrillos, NM 87010
Marcia Selsor on tue 27 dec 05
Michael,
That sounds great. Marc is a real wizard about burners, orifice
sizes. etc. I still don't understand 19 psi for raku kiln and 4-5 psi
for ^11. Sounds like much different efficincy in the burners.
Good Luck,
Marcia Selsor
On Dec 27, 2005, at 1:53 PM, Michael Lancaster wrote:
> Marcia's idea of tanks in tandem sounds great! I spoke at length
> with Marc Ward and we will soon be taking one of the burners off of
> our 80 cu ft soda kiln. We fire them at 4-5 psi reaching cone 11
> +. The high psi is because of the small orifice needed for a small
> venturi. I look forward to the change and the quiter burner
> (ransome B-4). I will probably wait till I build a larger kiln
> 3'x3'x3'.
>
> Michael Lancaster
> www.studio98B.com
> njlancaster@iglide.net
> 505-474-7564
> 98B Gold Mine Rd
> Cerrillos, NM 87010
>
> ______________________________________________________________________
> ________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Beth Tate on tue 3 jan 06
I live in Los Angeles area and was wondering if any of you can recommend a person to help me
create a portable raku kiln to use at the beach. I've seen some of the kilns one can buy but I may
have only one person to work with me and am looking for ease and portability rather than size.
Thanks in advance.
Beth Tate
Venice, CA
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