reekanmantell Posted March 31, 2011 Share Posted March 31, 2011 I am building a forge and came across hybridburners.com. I like the design and efficiency of those burners and have decided to play with my machining equipment and make a burner instead of buy one, however this leaves me with some questions. I have a copy of "Gas Burners for Forges, Furnaces, & Kilns", and the book has been incredibly helpful. I am milling and lathing my forge parts instead of using standard pipe fittings, and am stuck on the venturi. I read somewhere that a 20 degree angle is "optimal" for a venturi, but I want to verify this before I lathe the part. My question is this: what is the optimal angle for a venturi, and does anyone have previous experience with machining burners that they can give me advice (I see no reason to re-invent the wheel). Thanks in advance, reekanmantell Quote Link to comment Share on other sites More sharing options...
macbruce Posted March 31, 2011 Share Posted March 31, 2011 Maybe I'm full of it on this but a venturi is created whenever a larger volume (pipe)is pushed through a smaller one. I use a 2'' pipe necked down to an 1 1/4'' using bushings. I suspect if I made the transitions more efficient it would blow out the flame.......Then I would probably need to up to 1/2'' pipe.........A simple solution might work just as well.......If not I'm sure I'll hear about it B) Quote Link to comment Share on other sites More sharing options...
reekanmantell Posted April 1, 2011 Author Share Posted April 1, 2011 Yes, the venturi effect is created when you reduce the diameter of a pipe a liquid (gas) is flowing through. I know I can make the burner work by reducing the pipe diameter in just about any way, but I am specifically trying to build as optimal a burner as I can. If the venturi sucks in too much air I will have a choke to fix the problem (as well as a burner flare to reduce the gas pressure at the flame). Thanks for your suggestion, I do appreciate it! ~reekanmantell Quote Link to comment Share on other sites More sharing options...
tlreif Posted April 1, 2011 Share Posted April 1, 2011 Hi there. I make a knock off of the hybrid burners t-rex. If you lookup a post called my forge story on this site you can see some pictures of them. Anyway I bought one and then basically copied it. My reducing bell I machine out on the lathe. So mine looks a little different as i use a 45 degree angle on the outside. but the inside is 17 degrees. Cut 1/2 inch in on the inside diameter of 1 1/4 pipe and then transition to the 3/4 inside diameter at 17 degrees. My burners work beautifully. The other key is the nozzle. Good luck and I hope this helps. Quote Link to comment Share on other sites More sharing options...
kcrucible Posted April 2, 2011 Share Posted April 2, 2011 If it puts you at ease, your reduction can be exactly 0 and the burner will still work just fine. In my opinion, it's an unneccessary extravagence, primarily designed to "open up" more surface area to bring air in. The propane jet is going to be sprayed into the small shaft either way, creating X bars of suction/pressure in the smaller tube. That will dictate how much air gets pulled in and the same speed as the propane jet, basically. As far as I can tell the only thing that changes is the velocity of the air at the intakes. That may reduce some friction, and be a good thing, but not something I'd sweat greatly over. All this is to say, it's pretty much impossible to mess that part up. ;) Quote Link to comment Share on other sites More sharing options...
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