Propane Forge Air Volume and Pressure Problems

[Rick Toews]

I just completed a new propane forge build using John Emmerling's burner design from the Hammer's Blow 2006 article. I'm using a Dayton blower, 1/15 HP, 1530 rpm. Based on observing the forge at the 2009 Fall Conference, that forge had significantly more volume and pressure than my blower produces.

With my burner on top requires 2" plumbing with two ells separated with an 8" nipple, then coming down with 12" nipple coupled into the 8" nipple with gas 1/4" ell inside with .035 orifice (per John Emmerling recommendation), coupled to the gate valve and finally the Dayton blower.

Is my distance from gas and air assembly to far from the burner? Is my blower w/ motor undersized?

I need some recommendations and or suggestions please. Anyone's help would be greatly be appreciated.

Thanks, Rick

[Grant]

The problem is that blower. While it will move a goodly volume of air it has very little pressure. Once you start restricting the outlet you get very little air. A proper forge blower looks like this:

[Rick Toews]

Thanks Grant for your recommendation. Do you think with the suggested blower, the distance and the two ells will not restrict the volume or pressure, and work well? If so, do you recommend less distance? I was trying to get both the gas supply as well as the blower away from the heat, by being below the table of the forge mount area. Thanks again for your attention to my questions. Grant, I know you guys are the best! Rick

[Grant]

The piping should be fine. How big/how many holes in your burner? You have some sort of door for that? Lot of metal exposed to the heat looks like to me, might cause some problems. What is the black horizontal piece inside the forge?

[Rick Toews]

The forge is 16" long. Openings on ends are 8.5"w X 9.5" high. The sliding vertical doors have not been made yet. The burner is 3" square tube 8.5" long, just as John Emmerling's design. The burner has 19 holes created with the crayola's and the round steel piece has 9 holes somewhere near .25 dia. each. The horizontal steel inside is 1X1X.25 angle welded in place to contain the bottom edge of the kaowool. Otherwise the end plates only expose 1/32" proud of the brick and kaowool to the heat.

I appreciate your comments please.

Thanks, Rick

[Grant]

Well, you can't have steel structure inside the forge. The forge is made to heat steel to white hot. That angle will warp and drip liquid scale and burn out in no time. The steel on the ends will warp enough to prevent the doors from sealing which will allow more flame to escape further heating the steel and it will warp in ways you won't believe. You cannot use steel where it will be exposed to any flame.

[Rick Toews]

Thanks Grant for your recommendations. I'll remove the angles on each side, and rather capture the bottom edges of the kao with nichrome wire stitched through the pipe. I'll also cut the end plates up a quarter, away from the opening. Do you think that'll suffice?

Thanks again, Rick

[Brad Roland]

Do you have a picture of how the burner looks sitting in the forge? Grant is right, no steel can be exposed on the inside of the forge, otherwise it will just melt.

I would also use refractory or KAO wool to wrap around the metal opening on either side of your Forge, otherwise it will also get "Burned" or "too hot" ... not good if you are putting doors on it.

The doors that you put on it should also have some kind of fire brick, refractory or KAO wool substance that faces the inside of the forge. Like Grant says, no steel/metal can be exposed on the inside or it gets too hot and melts.

I think the length of pipe is fine if you have the right blower. Mine is easily as long as yours is and I have no problems. I even made a shutoff/butterfly valve because there was too much air going through it ... anyway, here's a picture of my forge, notice around the opening you can see the burnt metal because it isn't protected by some kind of Refractory or KAO wool ... This is before I put the shutoff/butterfly valve in.
Hope this helps you out.

[Brad Roland]

Here are some better pics to show the burnt metal ...

[Rick Toews]

Thanks Brad for the great help! How fortunate to have you guys as a resource. I guess I should be better about the, no steel in the forge. As I mentioned to Grant, I'll get rid of the steel angle, and cut the steel back 1/4" away from the opening. Do you think that is enough? I just hope the ITC 100 is protective enough of the kao hanging down at the front edge with the steel cut back. I also have steel down to the bottom edge of the burner with the kao wool flush to the bottom. Do you think this will be a problem or should it be cut back as well, allowing the kao to come right to the bottom edge of the burner?

Thanks again,
Rick