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potterpat

Natural Gas From Propane

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Hello,

I have a 12 cubic foot updraft gas kiln, with 4 burners made by Contemporary Kilns about a hundred years ago...or at least 30. At any rate, I successfully fired this kiln with propane for the past 25 years that I have had it. Now being in the city, I am having to switch to natural gas. I talked to my local furnace supplier, and they contacted Ward Burners- found out that my propane orifices were size 50, and that I needed size 39 for natural gas. So they ordered them for me. I have installed them, explained to the gas company all the specifics of the burners- (80,000 BTUs / burner) and had a plumber come and put in gas line and regulators etc.

 

So today we fired it up for the first time with natural gas... hmmm...very colorless flames that seemed bland. I used to only have the gas valve open just a bit with the propane, yet it was half open with the natural gas and still seemed not very serious...

 

Ideas?

Input?

what am I doing wrong?

 

Thank you for any ideas!

Pat

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Propane is higher pressure. So 1st off the whole process will feel a bit less with natural gas at 7 inches water column or 1/4 pound pound pressure. That said whatever you used to have the valve at no longer applies -its needs to be way more open Now.

Propane has more BTUs (hotter faster) so you make up buy having more gas going in now. Your orfices are larger now tp allow more gas. Turn it up more.Forget about what you used to turn it to.Where are you located?

Mark

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I am located in South Dakota. I used to live in the mountains, over a mile above sea level. Now I am not living at high altitude. I know when I lived there, I had placed a 2 inch block on the edges of my burner stand to elevate the kiln body. It seemed to help with air flow and the temp climb.  Not sure if that will be necessary now that I am not at high altitude.

 

Keep talking! I am taking notes!! :)

Pat

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Contemporary Kilns I think are natural draft so the air flow is a big deal-put the blocks back under as its not going to hurt and can help.

My guess is 3/4 on -not full will work good now. It may take almost all on you will need a good temp guage(digital) to see if it stalls.

Mark

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I am going through this as well, as I am switching to natural gas from propane for my fiber raku kiln. The Venturi burner I bought is supposed to be 100,000 btu, so should do well in my kiln. This is based on 7" w.c. pressure at my home studio. The kiln is 6# fiber, 1" thickness, 20" interior diameter by 24" high. The propane weed burner never had any problem getting to, or beyond, my glaze maturing temperatures, but the new natural gas burner seems to top out at 1850 F, and then only with much fiddling of distance from inlet port, covering the exit port, etc. I am going to rebuild the kiln and am thinking that the ports for the weed burner are too large for the ng Venturi. They are both about 4"x4". I am thinking I need to make the inlet port 3"x3" & leave the exit port the same since I can damper it with a piece of kiln shelf.

 

I have in my collection of stuff, enough 8# fiber, 2" thick that I will be able to make the walls over. Not sure there is enough for the lid too, though, but I could always double up 1" thick.

 

Any thoughts from gas kiln folks on the 1850 F top temperature will be appreciated. I think this should be able to exceed that if I get the ports configured correctly.

 

John Lowes

Buford, Georgia

http://wynhillpottery.weebly.com

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Raku kiln, updraft (flame under shelf, exit port in center of the top), and I have a couple of glazes that mature at Cone 05-ish. I was having a hard time holding onto he 1,850, but could stay in the 1,825-1,830 range easily. I was full open with a 1/2" ball valve, fed by a 3/4" line. The orifice in the Venturi is approximately 9/64" (it was sized by the Venturi manufacturer for natural gas.)

 

John

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