PotteryFilter: Incomplete gas kiln firing
July 31, 2007 3:22 PM   Subscribe

My father, a potter in Massachusetts, has been firing his Olympic DD17 natural gas-fired downdraft kiln with good results for several years. Recently, it's begun to cut out half way through the firing process.

It's a six year old kiln with six burners, three on a side. It's designed to fire to cone 10, which is about 2350F, though he's had it up to cone 11 on occasion. Right now, 1700 degrees seems to be the magic number for shutdown.

It's plumbed on its own natural gas line. He's installed two new thermocouples, which is what keeps the valves open and feeding gas to the burners. Somewhere around 1700F something generates a shutdown order to the thermocouples or the BASO valves and down it goes.

Email and conversation with the factory hasn't turned up much and internet research has turned up less. The only logical explanation I found for him is that the gas pressure isn't enough to sustain the higher temps, resulting in the shutdown. He's having a plumber come out to look into it, possibly removing one or more of the valves to simplify the firing process.

Sorry for the length -- my first question and I'm not a potter, so I wanted to give what detail I had. Any ideas? Thanks!
posted by Pantengliopoli to Sports, Hobbies, & Recreation (2 answers total) 2 users marked this as a favorite
I know nothing specific about pottery kilns, but it seems to me that any device operated at consistently high temperatures is bound to have parts that degrade gradually because of that; and if those parts are involved in keeping heat inside the space, then that would require, over time, more and more gas to keep the interior heated to any given temperature. So you might check for crumbling refractory linings, or air leaks, that would tend to cool the thing down faster than when it was new.
posted by flabdablet at 8:16 PM on July 31, 2007

1. The thermocouples - can you get a reading from them? Are they reading correctly?

2. Is the data being correctly interpreted by the valves? In other words, are the valves being prematurely closed by the thermocouples because they think it's hotter than it actually is, or they are set to shutdown at a lower temperature than desired?

A pressure gauge shouldn't be that big of a deal, you can install one after the second valve to see if you have sufficient pressure.
Email is in my profile, email me if you have some more questions, or details.
posted by defcom1 at 9:45 AM on August 1, 2007

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