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hanee

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  1. Thank you for the quick reply @neilestrick. With regards to power-burners, unfortunately I'm off-grid with a very minimal solar system. So venturis it must needs be. I do tends towards grogged bodies and know how to ensure my work is dry. Between that and possibly candling with a lower power Bunsen burner or pilot, I could probably stand a little more thermal shock than average, but still definitely not looking to fire at Raku speeds. The MR-750 is listed as going down to 17kbtu in several places. Not quite sure if that'll be slow enough. Worst case I could just waste the heat by opening the kiln a bit too much or throwing in a little thermal mass, but I'd rather buy or build the right burner or burner combo to begin with. One reason to build my own Venturis is that I could swap between a lower BTU geometry/orifice and a higher one half-way through the firing if needed. I can't afford one of the low-BTU Ransome's, let alone two. Hopefully someone chimes in on the pressure questions (otherwise I will indeed try contacting Ward Burners). (And yes, the BASO is part of the plan. But thanks for the reminder!)
  2. I'm trying to put together an order for a propane kiln I'm building and have a few questions that have arisen from advice that's not lining up both on these forums and elsewhere. First, because questions usually arise about the build. This will be a small 8-12cubic foot (maximum 30sqft internal surface area) fiber-kiln, probably initially will be tested out as an Ian Gregory style flatpack. The long term goal is building a similarly sized refractory lined fiber kiln for *clean* wood firing but I'm using propane and temporary fiber kiln designs to work out BTU needs/chamber-shape/etc... in all cases it's for mostly firing to Cone 010 - Cone 06 Oxidation for firing terracotta sculptures and some occasional Cone 6 Oxidation glaze firings for my wife whose just starting out in pottery. There is no intention to ever run a reducing environment or to ever run over Cone 6 (we're interested in being fuel efficient and clean burning with both LPG and eventually wood). So, as for the questions: At this scale and with the fiber approach, most people seem to be using a 0-30PSI adjustable regulator and something like an MR-750 venturi burner. Often people are using 'weed burners' as well with surprising success. All of this equipment is geared towards a Raku approach of very fast firing (which is not what I'm looking for) and bundled kits are sold for this setup. None the less, people *do* seem to be managing to bisque (Ian Gregory, Simon Leach, etc) using this exact set up. Based on research on these forums and elsewhere it seems to me that whether using the MR-750 or similar (or building my own venturi burner), my BTU needs can also be easily served by low pressure systems. My maximum BTU/hr needed is estimated at around 100k. I see two options that provide this capacity: (A) 11" WC system with (2) MR-750s or similar with an extra large flexible hose (1/2 OD 3/8 ID) vs the usual smaller ones because as far as I can understand the smaller hose would be the limiting factor on flow and as far as I can tell 3/8 ID would be required to get up 100k BTU/hr at 11" WC with a 10ft (minimum length I'm comfortable with safety-wise) hose. (B) ~5PSI system with (1) MR-750 or similar with standard issue 3/8 OD hose. With or without the regulator being adjustable. The biggest thing that's tripping me up right now is that while the most popular view is something like: "You need an adjustable regulator and high pressure to control the burner output and a dial to create a schedule" (these people are usually using portable raku-type setups) I've also read on this forum something like: "Pressure should be fixed because it has to do with orifice size, all control should happen with ball valve/needle-valve downstream of the regulator and NOT at the regulator" (these people are usually experienced in permanently plumbed kilns with larger diameter pipes and often with natural gas or residential propane where there's no control on pressure anyway). Also some advice indicates that low pressure is intrinsically safer and preferable. But I can't wrap my head around that beyond leak-pressure on fittings. If, in either case, I need at the end of my burner 100k BTU/hr, it would seem it didn't matter if I got that via high pressure and low volume or via low volume and high pressure -- the same amount of cubic feet of gas is going to be coming out. Leaks aside, if there was no BASO, a flame blew out, and you had a danger of pooled propane, it would be the same total volume of propane in both cases and the same exact risk. Also I've read some low pressure advocates saying that only low-pressure gives you the fine adjustability needed to bisque and yet I've read high pressure advocates saying high pressure is necessary to have fine control. So at this stage, I've got to settle the low-pressure/high-pressure decision and whether the regulator is a point of control or can operate on fixed pressure. Are these differences simply equivocal in my limited application or does one side truly have a better or 'more correct' argument? Thanks in advance to any who have any insight to offer...
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