Help please - Forge Burner Tuning - Pic included

Matt Brook · Jul 11, 2011

Hi Guys,

I have a WIP down the page a bit. Can anyone tell me if this flame looks right to you? Its a venturi burner on LPG at around 50kpa

Any help greatly appreciated

Matt

Dixieblade57 · Jul 11, 2011

Not bad for a down under fire!

I had to go look at your profile when I saw the 50kpa. I wasn't sure about that but I knew it had to be a metric standard.

50kpa converts to 7.2518869 Psi

I am not sure because I use propane and not LPG the pressure sounds a little high. But the objective is to get the blue flame like you have there with as little pressure as you can. Usually when you exceed that pressure your fire tends to go to the yellow look and you usually can smell the unburnt gas that is being expelled. So if you exceed that sweet spot you are not only wasting gas your fire is not any hotter and may not be as hot as it potentially could!

Blue is good, that means pretty much everything is burning. Are you getting a good vortex effect? In otherwords is the flame swirling around the forge, if it's not you may have to be concerned about a hot spot inside the forge. Even if you do tend to have a hot spot as long as you are aware of it you can work with it!

Others that use LPG may be able to shed a little more light on the subject!

Matt Brook · Jul 11, 2011

Thanks Dixieblake57

I seem to be getting a pretty decent vortex. I backed the pressure off a bit but didnt seem to make much difference. It seems to "hunt" a little bit though?

I am not sure if I have the burner to far back up the feed pipe. Is it meant to be sticking into the forge area?

Matt

Justin King · Jul 11, 2011

The burner tip should not be in the forge chamber, it will oxidize to a solid piece of fire scale, or even melt, if too much is exposed inside the chamber.
You might get a better vortex if you can angle the burner so it is hitting a little higher on the right wall of the chamber, I fooled with mine a bit and finally got it to hit the side at such an angle that it rolls into a vortex, instead of just spreading sideways where it deflects off the wall.

Bill Burke · Jul 11, 2011

your flame looks good. It It is had to tell from the picture but it could be a little bit on the rich side. I am judging this by the greenish tint. you will either need to increase the speed of your gas stream so it will suck in more air or make your venturi more efficent. By the way lpg and propane are the same, from wikepedia; Liquefied petroleum gas (also called LPG, GPL, LP Gas, autogas, or liquid propane gas)

Matt Brook · Jul 11, 2011

Thanks Justin and Bill

Greatly appreciated!

Matt

insanity · Jul 11, 2011

That pressure doesn't sound real high to me to start with. You will probably be able to decrease it once your forge gets up to temp. I like to run a slightly reducing atmosphere in a forge. You don't really loose heat and it helps cut down on scale. Burner tips are consumables. They will burn up. You can adjust things to make them last longer though. Pulling the tip back in the inlet is one and putting a metal that has a higher melting temp on the end is another. 300 series stainless is good. I want to try Ti eventually, but don't think I'll get around to it anytime soon. Your forge looks good. Before you spend too much time fiddling with things go ahead and use it. If it doesn't give you any problems then you don't have to change anything.

Wayne S

Matt Brook · Jul 11, 2011

insanity said:
That pressure doesn't sound real high to me to start with. You will probably be able to decrease it once your forge gets up to temp. I like to run a slightly reducing atmosphere in a forge. You don't really loose heat and it helps cut down on scale. Burner tips are consumables. They will burn up. You can adjust things to make them last longer though. Pulling the tip back in the inlet is one and putting a metal that has a higher melting temp on the end is another. 300 series stainless is good. I want to try Ti eventually, but don't think I'll get around to it anytime soon. Your forge looks good. Before you spend too much time fiddling with things go ahead and use it. If it doesn't give you any problems then you don't have to change anything.

Wayne S

Thanks Wayne,

I gave it a bit of a burn last night. It heated up some 1/4" by 2" stock ok. Took a bit but the liner still isnt 100% dry. I will keep giving it some heat over the next week and see how it goes on the weekend.

Thanks for the suggestions everyone. Its greatly appreciated!

Matt

insanity · Jul 12, 2011

How thick is the layer of cast refractory? 1 to 2 cm? Castable is durable, but takes a long time to come up to temp. It will suck a lot of heat from the forge at the beginning. The up side is that it holds it well and will help give a consistent temperature once things have equalized.

Wayne

Matt Brook · Jul 13, 2011

Thanks for the help everyone,

It takes about 10 minutes to get up to temp. Here are some more pics