davesnyder Posted December 25, 2016 Report Share Posted December 25, 2016 Hi, and best holiday wishes and a Merry Christmas to all~ I have a 55Gallon barrel drum Raku kiln, but even with two 300000btu brush torches I cant get past 1600F, and my Amaco Glaze matures at cone five, 1895-1900. Is there a burner that can get me to cone 05, or do I search for lower fie glazes? I've really been trying what I can dream up, but just cant hit that temp. Any Insights would be very helpful. Thanks! I have a 4" port, and a 6" exhaust. I have one layer of kiln blanket, and the 3" barrel bung open for exhaust. Link to comment Share on other sites More sharing options...
Guest JBaymore Posted December 25, 2016 Report Share Posted December 25, 2016 Dave, 600,000 BTUs is plenty to fire that to cone 05. Venturi or forced air burners? What gas pressure if venturi? What brand of venturi burners? This is going to sound strange.... but try turning the burners DOWN more than you have been "pushing" them to get the temp up. This is often a mistake people make who are not used to fuel firing. Sometimes you are just burning the fuel outside the kiln after the exit flue.... or not burning a lot of the available fuel at all....and it goes off with the flue gases. best, ......................john Link to comment Share on other sites More sharing options...
Marcia Selsor Posted December 25, 2016 Report Share Posted December 25, 2016 how do you have the burners positioned? Try putting them 2-3" away from the burner port. Don't have a flame coming out the top. Send a photo if you can. Marcia Link to comment Share on other sites More sharing options...
Marcia Selsor Posted December 25, 2016 Report Share Posted December 25, 2016 I fire one burner with 2 tanks plumbed for one burner with a regulator set at 4.5 psi. This avoids freezing tanks when the gas is low.I fire inside my kiln shed to avoid heavy dew and wind. Link to comment Share on other sites More sharing options...
Marcia Selsor Posted December 25, 2016 Report Share Posted December 25, 2016 Since I just moved to Montana, I will be building an outside protected area for my raku kilns. I will be building a new topcoat top of kiln wit 8# density fiber. I have to wait til the ground thaws.The bulk of the studio will be arriving tomorrow, I hope. The kiln below was at my Montana studio in Billings from 2001-2006 Link to comment Share on other sites More sharing options...
rakukuku Posted December 25, 2016 Report Share Posted December 25, 2016 I would guess you are not getting enough air. Might try using some kind of blower to get more in. Our old raku kiln had a homemade burner and needed the blower to get the last 100 degrees. Then we replaced it with a venturi burner and it works well. No issues. But we also have it hooked up to natural gas. GL. Rakuku Link to comment Share on other sites More sharing options...
Marcia Selsor Posted December 25, 2016 Report Share Posted December 25, 2016 by brush torches do you mean weed burners? They are not the most efficient burners, especially without a regulator. They should be able to hit temperature if you set up their position to get more air by pulling them away from the burner port. Turn them on low and increase every 10 minutes..3-5 times. You shouldn't need to have them fully open.If you want to buy a good setup, contact Wardburners.com Mark Ward will be a great help to determine what you need. Marcia Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted December 25, 2016 Report Share Posted December 25, 2016 My guess is that you are inducing too MUCH air rather than not enough. Marcia is correct about starting off at a lower firing rate. Install a pressure gage in your fuel line between the control valve and the burner tip. Use that pressure reading to measure​ the amount of fuel to the burner. LT Link to comment Share on other sites More sharing options...
Guest JBaymore Posted December 25, 2016 Report Share Posted December 25, 2016 How did I miss that line "brush burners". DOH! OK......... not great burners. Hugely dependent on secondary air. The lower they are run for supply pressure... the less % of Primary air they pull in. At BEST they pull about 50% primary. Such a kiln only pulls secondary minimally.... and better when hot. Back to turn them DOWN and creep them up SLOWLY as far as gas pressure goes. Don't "put the pedal to the metal" and expect it to burn IN the kiln. Maybe add a short temporary stack like in Marcia's one picture. best, ....................john Link to comment Share on other sites More sharing options...
Marcia Selsor Posted December 27, 2016 Report Share Posted December 27, 2016 this is my venturi burner running on 4.5 psi positioned about 1 1/2-2" from wall of kiln. Primary air is low and the gas is low. Marcia Link to comment Share on other sites More sharing options...
neilestrick Posted December 27, 2016 Report Share Posted December 27, 2016 Is there a shelf inside the kiln? How high above the burner port is it? How much room between the shelf and the fiber? What I'm asking is whether the shelf (if there is one) is blocking the air and heat flow. Link to comment Share on other sites More sharing options...
Benzine Posted December 28, 2016 Report Share Posted December 28, 2016 I had a similar issue, when I started Raku firing. John B. gave me the same advice he gave here, and it worked. My solution to a slow heating/ stalled kiln temp, was to crank the burner. Obviously that didn't work. Another recommendation was that I widen my intake and outtake ports. I did so by about an inch. Both of those things helped, and my kiln fires quite well now. I can always tell, when I've got the burner cranked too high, because I see some pretty good sized flames coming out the top. This is when I back it down, or pull the burner further from the intake. Like many have said, you need to get more air in. I use a single weed burner, no blowers or anything of the like. But it does need a good gap between the burner and intake, so some of the surrounding air can get in, and help the gas burn. Link to comment Share on other sites More sharing options...
Guest JBaymore Posted December 29, 2016 Report Share Posted December 29, 2016 But it does need a good gap between the burner and intake, so some of the surrounding air can get in, and help the gas burn. Weed burners are basically "junk" burners. They are not intended for what we do with them. They work just fine for what they are intended to do though........ because things that matter to us don't matter to someone burning off unwanted weeds. The absolutely BEST available venturi type burners can entrain only about 65-70% of the air they need to combust all the fuel. It is a limitation of the designs. It simply cannot get better than that. And those burners are not the ones typically used by the vast majority of studio potters. Companies like Pyronics and North American make those types. They are expensive. (I have four Pyronics ones on my gas kiln. They are precisely engineered and cast units. Beautiful.) So to burn all the fuel coming out of that orifice .... you MUST supply secondary air. To do that... the burner/kiln SYSTEM must work together to entrain and MIX that extra 30% into the already burning and partly aerated mixture before it leaves the chamber. The engineering start point for designing kilns is AIR.... not fuel. No air...... no heat energy. best, ................john Link to comment Share on other sites More sharing options...
Marcia Selsor Posted January 1, 2017 Report Share Posted January 1, 2017 I agree. Weed burners are junk. They are not intended for kilns although you may be able to hit temperature , you'll burn a lot of propane doing it. Also regulators are really important to use with propane. Marcia Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.