hammerwolfe Posted May 17, 2011 Share Posted May 17, 2011 I have used these burners for many years and at times I have had small flash back problems ... but they have never lasted.. I have constructed two new burners and they work great and the flame looks very good but the slightest change and they go into the flash back mode or Back pressure mode....... by shutting the main gas valve and turning the valve back on the problem temporally goes away.Anyone out there with any experience with the back pressure????? Any input would be appreciated..... Thanks .... Mike.... Quote Link to comment Share on other sites More sharing options...
Steve Shimanek Posted May 18, 2011 Share Posted May 18, 2011 What kind of flame retention device do you have on your burner tubes? For blown burners it seems they work best with some kind of partial restriction on the end of the tube. I am no expert but I recently built a 4 burner blown forge and am using a sink strainer (modified) inside each tube. I tried using those stainless steel scrubbers in the tube and that worked also but since my tubes are vertical they don't stay well. Some designs seem to use burner tubes crimped on the ends. Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted May 18, 2011 Share Posted May 18, 2011 What exactly do you mean by "back pressure mode"? Quote Link to comment Share on other sites More sharing options...
gearhartironwerks Posted May 18, 2011 Share Posted May 18, 2011 I have used these burners for many years and at times I have had small flash back problems ... but they have never lasted.. I have constructed two new burners and they work great and the flame looks very good but the slightest change and they go into the flash back mode or Back pressure mode....... by shutting the main gas valve and turning the valve back on the problem temporally goes away.Anyone out there with any experience with the back pressure????? Any input would be appreciated..... Thanks .... Mike.... It seems as though you're not getting enough air to accommodate the gas and the burner tubes are heating up. I've seen smiths introduce a small tube of compressed air. Don't know for sure as I'm a ribbon burner fan. JE Quote Link to comment Share on other sites More sharing options...
hammerwolfe Posted May 18, 2011 Author Share Posted May 18, 2011 Thanks Steve, Grant, John for your replies. In reading articles on gas forges with blowers the words"flash back or Back pressure"is mentioned, I guess I put in the term "mode" and what i should havesaid is the word "problem"....so what i am talking about is when thefan blower LP gas forge is working fine and every thing is heating up andeverything is sounding good,,, Then all of a sudden a large roar starts and youcan hear that sound that you hear with a acetylene torch, when you get flashback. All I have to do is cut the gas valve for a second and turn it back onand it works till the next time it feels like doing the roar.. As far as the question on what are the "end of theburner tube restrictions" well it is the sane exact design as I have usedsince 1986 when i built my first Hans Peot designed LP gas tube forge.. His burner end uses concentric tubes 3 inches long startingat the outer main tube 2in dia. the next is 1 1/4 then 3/4 then a solid 1/2 rodall are separated with a series of 5/32 spacer rods. The flame at the end of the tube looks great and the forgeheats up fast and gets hot. but you never know when it will flash back.. I have built many of these forges at least 8 over the last 25 years, yes I have had someflash back problems over the years but not like this forge and burner, By the way this is a big forge it is 24 inches long... 12inch in diameter, and uses 2" thick Kao-wool, half thick fire brick floorand fire brick ends, See attached drawing... Again any input would be greatly appreciated,,, Thanks,,, Mike Quote Link to comment Share on other sites More sharing options...
hammerwolfe Posted May 18, 2011 Author Share Posted May 18, 2011 Here is the Drawing of the Tube forge that would not download yesterday... Thanks ... Mike.... Quote Link to comment Share on other sites More sharing options...
Frosty Posted May 20, 2011 Share Posted May 20, 2011 Sounds like your burner tube is getting hot enough to pre-ignite the air fuel mix. Two potential causes come to mind. First you have the tube extended too far into the forge chamber, try pulling it back a ways and see what happens. Second is the flame holder, often the philosophy of a little is good more must be better does more harm than good. Try removing the outer ring of the flame holder and see what happens. This will allow more movement along the burner tube and more cooling. Lots of guys come to work arounds but making the burner and tuning it correctly generally eliminate most problems. And yes, pre-ignition is a pretty basic problem often produced by the enough is good more is better theme. Don't sweat, we've all done it and heck still do, especially exploring new territory. Frosty the Lucky. Quote Link to comment Share on other sites More sharing options...
Dodge Posted May 28, 2011 Share Posted May 28, 2011 Here is the Drawing of the Tube forge that would not download yesterday... Thanks ... Mike.... My older forge is a scaled down version of this one using 6 x 15" fire chamber and a 1.25" burner instead of 2". It will melt 1/2" square at its lowest setting whether you want to or not .... DAMHIK B) Quote Link to comment Share on other sites More sharing options...
sfDuck Posted June 11, 2011 Share Posted June 11, 2011 How are the blades in the fan? They could get a covering of dirt on them which changed the amount of air introduced into the burner. Either change the setting on the blade valve to get more air or use a bottle brush to clean to clean your fan blades; asumming this is a squirrel cage fan.But cleaning the fan is where I would start. Then see if the performance changes. Solving problems like this is a process of elimination, till things are corrected. I learned this one on a 5 million btu boiler about the size of a large freezer filled with cement. It was dancing accross the floor of the room and shaking the building when it fired. I was a little inexperienced with Large boilers and called the boss out who said why do you think I sent you out here to clean the boiler! Experience is great isn't it? Try this and post again if it does not change. Have Fun Quote Link to comment Share on other sites More sharing options...
sfDuck Posted June 15, 2011 Share Posted June 15, 2011 Hi Hans the next thought that came to me was the condition of your 1/4 inch tube for propane, it might have some crude on the end of it; or try moving it in a little. Just a guess or two. Have fun! Quote Link to comment Share on other sites More sharing options...
edge9001 Posted June 15, 2011 Share Posted June 15, 2011 I have the same forge with the same design causeing the same problem. lol i guess between the two of us we can figure out the problem Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.