Erik Poulson Posted January 12, 2021 Report Share Posted January 12, 2021 Hello all! I have just returned back to the Ceramic world after a decade plus long break. I got my studio set up, produced a kiln load of work, and am now in the process of firing. Unfortunately I have stumbled across a firing problem that I'm not quite sure how to solve. I have an old 10cu ft updraft Olympic kiln. It was originally set up to use natural gas. I fired all the way up to cone 10 many times with it without any issues. Due to my current location I had to convert it over to LPG. The burner setup is so old that Olympic bo loner makes the lpg orifice so I had to drill them out. They are connected to the gas supply with a 1/2psi regulator. So here's the thing... once I turn the burners up past a decent candle flame I'm getting a lot of excess carbon/soot. So much so that you not only see/smell it in the air it is also covering the most exposed work. I've adjusted the air intakes on the burners with little to no effect. I dug out all my books and can't seem to nail down the issue. I know it has to be something in the air/gas mixture but I just can't pin it down. Anyone out there able to help a guy just wanting to fire his pots?!?! Link to comment Share on other sites More sharing options...
neilestrick Posted January 12, 2021 Report Share Posted January 12, 2021 You drilled the orifices larger than before, or you got new orifices and drilled them to the appropriate size? Link to comment Share on other sites More sharing options...
Erik Poulson Posted January 12, 2021 Author Report Share Posted January 12, 2021 Drilled existing out to appropriate size. Olympic no longer makes/sells replacement orifices for my kiln (its like 40 years old!) Link to comment Share on other sites More sharing options...
neilestrick Posted January 12, 2021 Report Share Posted January 12, 2021 8 minutes ago, Erik Poulson said: Drilled them out to appropriate size. Olympic no longer makes/sells replacements for my kiln (its like 40 years old!) Still not clear. You drilled the old orifices larger? Propane orifices should be smaller than natural gas orifices. If you made the orifices larger, then that would account for the excess fuel and resulting soot. Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 12, 2021 Report Share Posted January 12, 2021 26 minutes ago, Erik Poulson said: Drilled existing out to appropriate size. Olympic no longer makes/sells replacement orifices for my kiln (its like 40 years old!) Picture of your burner would help and how many BTU is it rated for (natural gas) at what operating pressure. Neil is right if you drilled them larger then that was opposite of what was required. Fortunately you can get orifices for most burners, even blanks , often even really old ones. There is no way to tell you what size though without knowing old BTU, Pressure and new desired operating pressure on propane. Typical max. operating pressures : nat. Gas and propane (4 in wc - 8 in Wc ). 1/2 psi is just shy of 14 in Wc. Link to comment Share on other sites More sharing options...
Erik Poulson Posted January 12, 2021 Author Report Share Posted January 12, 2021 21 minutes ago, neilestrick said: Still not clear. You drilled the old orifices larger? Propane orifices should be smaller than natural gas orifices. If you made the orifices larger, then that would account for the excess fuel and resulting soot. Well, that makes sense. I drilled the original orifices with #40 bit making them larger. That was advise I got from Olympic when I called to get replacement orifices. Maybe the person who i talked to had the wrong information. They did tell me they stopped using the burner setup i have a long time ago because the company that made them went out of business. Orifice too large equaling too much fuel. What is the proper orifice size? Link to comment Share on other sites More sharing options...
Erik Poulson Posted January 12, 2021 Author Report Share Posted January 12, 2021 21 minutes ago, Bill Kielb said: Picture of your burner would help and how many BTU is it rated for (natural gas) at what operating pressure. Neil is right if you drilled them larger then that was opposite of what was required. Fortunately you can get orifices for most burners, even blanks , often even really old ones. There is no way to tell you what size though without knowing old BTU, Pressure and new desired operating pressure on propane. Typical max. operating pressures : nat. Gas and propane (4 in wc - 8 in Wc ). 1/2 psi is just shy of 14 in Wc. The placard on the kiln says 350,000 per hour. Five small burners. Can't get a pic at the moment as the kiln is still hot. Will send when I can. Link to comment Share on other sites More sharing options...
Mark C. Posted January 13, 2021 Report Share Posted January 13, 2021 Propane orifices should be smaller than natural gas orifices as Neil said . This is your issue propane is smaller holes-always-its a fact Just get new undrilled orfices and start over they are cheap.Smaller for propane larger for natural gas Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 13, 2021 Report Share Posted January 13, 2021 @Erik Poulson “I drilled the original orifices with #40 bit making them larger. That was advise I got from Olympic “ Hmm, so five burners 70,000 btuh each, natural gas already should have had a much larger orifice in them than a number #40 drill (.0980”). The orifices in them for nat. Gas were likely #28 or .1405” diameter. All dependent on top design pressure though. If you had a #40 drill it would have been swimming in the old gas orifice hole. I think the #40 drill size given by paragon is good actually, so check the drill being used before you drill new orifices. For reference: Propane contains prox. 2500 btu per cu ft. Nat gas about 1000 btu per cu ft. So propane has more than double the energy per unit than natural gas. Link to comment Share on other sites More sharing options...
Sorcery Posted January 14, 2021 Report Share Posted January 14, 2021 I soldered my old hole and drilled it correct. Worked. Sorce Link to comment Share on other sites More sharing options...
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