stalled kiln

updated fri 31 may 96

Dan Wilson on thu 25 apr 96

Your problem sounds familiar to me. I fire a 7 footer to cone 10 on one 25
gal and one 10 gal tank hooked up in tandem with a valve that enables me to
switch from one tank to the other during the course of the firing. You may
know that as propane escapes from your tanks its temperature decreases and
its pressure decreases. If left alone this process eventually freezes the
propane. Experience has shown me that when the volume of gas leaving the
tanks reaches higher levels this cooling process happens faster until an
apparent state of equilibrium is achieved in which the pressure at the
burners drops and remains at levels which are inadequate for firing. I've
also found that ambient temperatures and relative humidity affect the
cooling process as well. I've not found the solution to this problem but I
have found that when I fire between cones with the big tank and reduce with
the small one I delay the freezing process enough to do two cone ten
firings and three bisques. I also try to fire during times when the
temperature is above 50 degrees and the humidity is low. What this boils
down to is you need to increase the volume of gas you have in reserve, say
to 1500 gals? Sounds enormous to me. Any way, here in the Northwest where
humidity is high and temperatures are hover at 50 degrees most of the year
it seems. I've gotten used to having a room full of glazed pots waiting for
the right conditions to be fired. Good luck.

John Jensen on sat 27 apr 96

I've been waiting to read how this stalled firing turned out. As I remember the
post the propane was supplied at 30 water collumn inches at the max, which is
just a bit over 1psi. This doesn't seem like enough fuel to fire a 40 cubic
foot kiln. I usually end up firing my 15 cubic foot kiln (in oxidation) with
3.0 PSI. At 1.5 PSI I doubt I'd get past red heat. (four 75,000 BTU
atmospheric burners)

John Jensen in Annapolis, 76053.1462@compuserve.com

Cobalt1994@aol.com on tue 30 apr 96

I agree with John about the pressure not being high enough on that firing. I
fire my 36 cu ft propane downdraft with 4 B-4 Ransomes. I turn them up 2
ounces at a time, starting at 10 ounces. I max out at 20 ounces, although
Uncle Harry (Dedell) says I could go up to 32 ounces if I needed it. I
didn't respond before because I couldn't find a formula for converting water
column to ounces. Any one got it to post?
Take Care
Jennifer in Vermont
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
email: Cobalt1994@aol.com
snail: Jennifer Boyer
Thistle Hill Pottery
HCR 32 Box 755
Montpelier, Vt. 05602
Voice: 802-223-8926
Fax: 802-223-1180
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*

WardBurner@aol.com on mon 6 may 96

Hi Jennifer,

Sorry it's taken me awhile to answer your question about pressure
conversion...been outa town. 27.7 inches of water column equals 1 pound per
sq inch (PSI). 16 ounces also equals 1 PSI.
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com

Jennifer wrote:
<<<firing. I
fire my 36 cu ft propane downdraft with 4 B-4 Ransomes. I turn them up 2
ounces at a time, starting at 10 ounces. I max out at 20 ounces, although
Uncle Harry (Dedell) says I could go up to 32 ounces if I needed it. I
didn't respond before because I couldn't find a formula for converting water
column to ounces. Any one got it to post?>>>>