Jump to content

Recommended Posts

So, I was firing the gas kiln last night to cone10 and didn't even reach 1psi on my regulator. Thought I could share my figures.

 

The orifice I am 99% sure was 1.5mm or about 1/16th which olsen tells me has a fuction 10,492.70 and 1psi has the function 4.2661. If you multiply them both together you get the BTU which gives me 44-45k BTU max for a size of slightly over 6 cubic foot.

 

I think I am looking at 6-8k btu/cf for my gas kiln conversion even with thin electric kiln walls.

Share this post


Link to post
Share on other sites

I'm terrible at this math stuff...according to the Ward link my 2' x 3' x 4' downdraft requires...?...I'm never sure.

That said, my kiln is only 4 1/2" softbrick thick with a 1/2" outer layer of fiber blanket sandwiched within sheet steel and a 7" softbrick flat roof and about a 12' chimney.

 

I have two squirrel cage blowers on with 2" Sticktite burner tips on about 12" length pipes with the appropriate propane sized orifices.

My propane tank is a 250 gallon that has 1" gas pipe running about 22' away from the valves.

 

It takes a lot of adjusting and monitoring to get this puppy to cone 10 which is why I decided to go with cone 6-7 clay and glazes last year.

 

Per Ward's formula 2' x 3' x 4' x 30,000 BTUs/cu. ft. = 720,000?

 

At any rate, I can do a strong cone 7 firing, fairly even in 8-10 hours.

 

IMG_6152-XL.jpg

Share this post


Link to post
Share on other sites

10,000 btu/ft3 seems a good estimate so 240,000 btu/h for your kiln. Smallest burner on the website seems good for that. I have found with my kiln it seems to use even less that that. Never actually measured it though.

In the ward article raku burners are made powerful to quickly fire the pot so I think the 30,000 is way off. The 16,000 9" hard brick might give a better representation to what you have but even then probably worse that 4.5 insulating brick.

Edited by High Bridge Pottery

Share this post


Link to post
Share on other sites

Yeah, you'll need to figure out the BTU requirements for 4.5" of brick. In addition to being thinner than the typical 9", there are more gaps, unless you've mortared everything tight and the joints haven't split.

You can build those burners pretty easily. The things that cost the most are the retention tip at the end of the burner tube, the pilot valve, and the gas solenoid valve. The pilot valve shuts down the gas if the pilot light goes out, because without a pilot the main burner won't re-light if it goes out, and you'll be pumping unburned gas into the kiln. The solenoid valve works via electricity, so it will shut down the gas if the power goes out, because if the blowers shut down then you'll be pumping pure flaming gas into the kiln, and there will be big flames shooting out of every hole. You can probably build those burners for $600-ish.

Share this post


Link to post
Share on other sites

I think I'll stick with my burners as you suggest, and maybe add the little venturi pilot burners from Ward or someone. Then add the solenoid and baso.

But I'm pretty lazy til I get my ADD on...

Share this post


Link to post
Share on other sites
1 hour ago, Rex Johnson said:

I think I'll stick with my burners as you suggest, and maybe add the little venturi pilot burners from Ward or someone. Then add the solenoid and baso.

But I'm pretty lazy til I get my ADD on...

If wind isn't an issue, just get the little Honewell target pilots. They work great, and you can get them really cheap from other sources online, like $25 each.

Share this post


Link to post
Share on other sites

Well, thought about that, but the kiln is outdoors, and a windy desert outdoors, so...it'd be good to have a little more powerful venturi like Ward sells to do candling anyway. I candle with the main burners, fans off, until it gets up to at least 700-800 degrees before I flip on the fans and turn the gas up.

Creates a bit of soot and isn't real reliable ass far as the flame retention remaining  inside the ports.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

By using this site, you agree to our Terms of Use.