Recommendation? Forge Question

Chris Lyons

Chris Lyons

Joined
Feb 22, 2017
Messages
89
I seem unable to run my burner under 5psi, any idea what I could to differently to get it to run lower psi? I'm blowing through propane over here and I see that most people forge at around 1-2 psi in general.

Orifice is a #61 hole. I know it is centered down the burner tube because I hooked a hose up to it and adjusted the water stream. and I know that the burner to chamber ratio is good. I cant recall the numbers, but I checked before I did it. its a freon tank with 2" kaowool. the orifice is in a brass nipple (ron reil style burner). Does that hole deteriorate over time? I doubt it and I mean it hasnt been that long... but I was thinking maybe heat going up the pipe after turning it off could be ruining it somehow? I was also thinking maybe sticking a hose attached to a hair dryer on the air intake and making it a sort of rigged "blown burner"? Could that help?
 
I thought ventri burners generally ran at a higher psi than blown burners do.
Seems I've heard 10-12 on ventri and 2-5 on blown. I could be off though.
 
Clean your orifice first.

It doesn't matter what the pressure is, volume is important. If it is back burning, the flame is burning faster than the volume of gas is coming out.

Increasing the size of the orifice will usually fix the problem. Make sure you make tiny increases untill it burns better.

Hoss
 
it is not back burning at all and it runs really well at 5-7 psi. I am just trying to get it to burn as well at a lower psi to use less fuel for the same heat. It seems I will need to add a blower.
 
I haven't seen a venturi that runs much below 5PSI. Blown burners run at 2-3 PSI. The difference is that a blown burner has no orifice and does not draw in the air by venturi. The gas stream from the orifice in a venturi draws the air in.

As Hoss said, try a different orifice. The venturi burners I have built used a #30 MIG tip (,030" orifice), and ran on 5-15 PSI..
 
Stacy E. Apelt - Bladesmith said:
I haven't seen a venturi that runs much below 5PSI. Blown burners run at 2-3 PSI. The difference is that a blown burner has no orifice and does not draw in the air by venturi. The gas stream from the orifice in a venturi draws the air in.

As Hoss said, try a different orifice. The venturi burners I have built used a #30 MIG tip (,030" orifice), and ran on 5-15 PSI..
Click to expand...

Could just pipe a hair dryer or similar over the back of my bell reducer coupling to force more air instead of allowing the fuel stream draw it alone? or is this a bad idea for any reason?
 
That would probably not work well. The air/gas mix in a venturi is regulated by the venturi effect. If you added more air, it would not be well regulated, and could make it worse.
 
I can run this burner as low as 3 psi in my drum, but it wouldn't run that low in a smaller forge. 5psi was the minimum when it was in a smaller chamber.

It has a .045 diameter weld tip for an orifice.

IMG_20170914_25452.jpg
 
How about a picture or details of your forge? At 42K BTU, your forge is probably running cold, but we don't know because we don't know what size the chamber is. The burner I sell for that size forge(freon tank up to propane tank) produces 100K at 20PSI. That's about 4 hours per 20# tank. It is what it is, a big forge w/ a 6" chamber to forge 2" blades in. That's going to be a lot of wasted heat. That's why my Atlas Mini is so popular, it runs very hot at only 30K BTU with a 2.5" chamber. Keep your freon tank forge for when you need to weld a giant billet or forge a large axe, or buy stock in Praxair because you'll be wasting propane with a big forge.


Calculate Burner Heat output in BTUs Submitted by: Thomas Vincent

Enter the Propane Gas orifice dia. in inches
0.038 inches
Enter the propane pressure in psi
5 psi
Orifice discharge coefficient 0.75 Coefficient Note: *
BTUs per Cu ft. 2498 BTUs / cu. ft.
Air to propane ratio for (1 cu ft of propane)
23.86 cu ft per min.(CFM)
BTUs per Lb of propane
21,591 BTUs / Lb.
Propane weight per gal. 4.24 Lbs / gal.
Burner Heat out put in BTUs 42,378 BTUs per hour
 
inside dimensions of the forge is roughly 9"L x 5"W x 4-1/2"H. the front opening is usually covered with bricks when in use.
this is also the first forge I ever built (not counting that coffee can crap) and I really like it, I just wish I could make it more efficient because I am running through a 20lb tank every 2-3 days.
Granted it usually am out there for 3 or 4 hours at a time, just seems to be going too fast...


Also, how often should I be replacing the guts? the fire brick floor is getting pretty torn up from the flux. :/

QgxaENl.png
 
Flux will eat the wool and firebrick like water on Cotten candy. Thy must be coated in order to last any amount of useful time. Psi means nothing is gas flow that matters. You say you going through a lot of gas. How much is a lot of gas. When I was running a BBQ size tank I would burn through that in 5-8hrs depends on what your doing with the forge. This also depends on how efficient the forge is made. Forge welding straight up eats gas, but it's the pricy you pay to play.
 
Actually is neither the flow, but the velocity of the gas affecting the venturi burners efficiency, it is all in the design. That's why you can have a wide range on blown burners, and why you should build (or better get; those black iron pipe ones are rough approximations of a real Venturi) different size venturi burners for widening their narrow ranges. You cannot change the orifice without changing the air channel and expect to run the same efficiency.
My forge looks like DirtDiver61's, but i have 2 burner ports, and 2 sizes of venturi to select from, depending on the operation....going with 1 port/ 1smaller burner for HT to 2 ports/2 larger burners for welding. I have no complaints on gas consumption.
Good insulation pays the most when it comes to saving money on forges, a thing to remember
 
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