More forge and burner questions from a newbie

[Lab-lover]

Hello everyone, thanks for letting me join this forum. I realize many of these questions may have been asked before so if you are tired of answering them, please just direct me to the appropriate posts for the answers. 

My son and I have just jumped into this activity and have attempted to build our first propane Venturi burner. The dimensions are a 3/8” brass shutoff leading into 1/4” black pipe feeding a .045 welding tip (we also tried a .025 tip). This nozzle sets 1.5” into a 1.5” x 1” intake reducer which connects to an 8” x 1” black pipe nipple and finally to a 1” x 1.25” reducer. This last reducer sits on a matching hole in the soft firebrick top of the forge. All of this is fed propane from a 20lb propane tank with a 0-60 PSI regulator.

I will add some pictures of the build to help clarify the above description. I will also add a video of the flame we are producing. It does have something of a blue cone but it seems ragged with orange tails. We are able to get a piece of 5/8” x 4” coil spring steel to resemble a nice orange Cheeto but can’t seem to get it any hotter. 

Finally the questions; Why do we need 30 PSI to achieve a blue cone? How do we increase the heat output? Is it normal for the output reducer to get as orange hot as the target steel? Why does the flame keep wanting to blow back up into the black pipe nipple? Could part of the problem be that our forge is just loosely piled hard firebricks which probably has considerable air infiltration? If we can get the flame production and high PSI requirements figured out then we will build a properly sealed firebrick forge if you think that is adequate to use.

Thanks in advance.

[Buzzkill]

Welcome to the forum.  If you haven't already done so, you should read the Read This First topic which you can find in the blue bar at the top of the page.  That will help you get the most out of the forum.

The threads we have on gas forges and burners are some of the most active on the forum, and as a result they tend to be quite lengthy.  However, nearly any question you will have has probably already been answered there.  Here's a couple links to get you started:

https://www.iforgeiron.com/topic/46536-burners-101/

https://www.iforgeiron.com/topic/47439-forges-101/

If you still need help or have further questions after reading through those let us know and we'll help you get sorted out.

[ThomasPowers]

Using hard firebrick is rather like turning on your house's furnace and opening all the doors and windows and then wondering why it's not getting warm.

Now a lot of folk with this issue say they can't afford to get decent insulative refractories; which is odd as they seem to think they can afford to spend many times their cost in buying propane.

[Mikey98118]

2 hours ago, Lab-lover said:

I will add some pictures of the build to help clarify the above description. I will also add a video of the flame we are producing. It does have something of a blue cone but it seems ragged with orange tails. We are able to get a piece of 5/8” x 4” coil spring steel to resemble a nice orange Cheeto but can’t seem to get it any hotter. 

From what I can see of the flame, it is superior to anything expected from that burner

Don't worry over a ragged flame; it looks axially true, so it is probably stable. I have made some very hot ragged flames in the past. Also, don't worry about the "orange Cheeto" just yet. Your flame retention nozzle may be oxidizing surface coatings for a while.

Soaking the burner.s flame retention nozzle in vinegar overnight will get read of that coating, without breathing any of it.

[Welshj]

they've pretty well covered it.

I'd just add that the reason the firebrick doesn't work that well- they're huge heat sinks. They will retain the heat, vs reflect it. What you want from a forge is insulation from the heat to your outer surface yes... but you also want the heat to stay trapped in the forge... reflected back. Bricks are great for an oven shell, not so much for a forge body.

From the way that I understand it- you want the burner to heat the forge, not the steel per se. The burner heats the forge, the forge retains the heat, the forge evenly heats the steel when inserted. 

Tried and true methods of refractory over ceramic wool is a great example of that.

And get rid of every single bit of that white Teflon tape on your gas lines in the future!

Its not rated for propane. That's a yellow colored tape in the us for propane.

[Lab-lover]

Thanks for all of the great info!!! I normally use gas rated pipe dope on the joints but didn’t have any handy so used the tape for a quick test and will replace it asap. 

I understand that part of my problem is that the fire brick is a heat sink. Would coating the inside bricks with refractory help reflect the heat and make it more efficient or is that a waste of time and effort?

Is it normal for a naturally aspirated Venturi burner to require 30 PSI? A 20lb propane isn’t going to last long at that rate. I keep reading about people achieving hot flames at only 2 PSI. How is that possible?

[Mikey98118]

Yes, it certainly well help.

30 PSI is kind of high. We recommend 0 to 30 PSI regulators; not gas pressures.

What size gas orifice?

[swedefiddle]

Merry Christmas Lab L,

You will find that you turn the pressure up to get the Forge up to temperature, then you can adjust the pressure way down. Don't be too hard on yourself, we all started somewhere. If bricks is what you have, bricks is what you use. It takes about 20 minutes for them to come up to temperature. Guess how I know!! This is not your last Forge, this is your 'First Step'. Learn from it, learn what works and what doesn't work. Keep a log book with your notes, You can always look back and see what did or didn't work. Pay attention to yourself, stay safe!! You will learn what works for you, at your location, with your equipment, Pay Attention.

Neil

[Welshj]

I run my forge on an average of 5-6 psi. But, I use a forced air style burner- not venturi. From my understanding with venturi burners you need the higher pressure to pull in the air. 30 psi is kind of excessive like Mikey stated.

(He's one of the burner gurus/experts btw. A wise thing to listen to his advice.)

[Lab-lover]

Mikey98118, I have a 0-60 gas regulator and I have tried a .023 and a .045 welding tip. The video showed the results with the .045 tip installed at 30 PSI. If I reduce the gas pressure much below that the flame wants to back up into the burner tube.

Swedefiddle, I realize this is just a first attempt and I am FAR from giving up (in fact I seldom do quit once I begin). I am just asking for help in diagnosing our current set up and what to do next to improve our process. We are having fun playing with the forge but I feel we are ready to take the next step in producing a hotter environment.  
 

Welshj, we are open to stepping up to a forced air burner at some point but would like to understand more about our Venturi burner first. I may build a Frosty T burner just for the fun of comparing the two types. 

[Mikey98118]

Okay, that is enough information to work with. I suggest that you build or buy another flame retention nozzle. You can use the information in Burners 101, or (and this is your best more). buy a nozzle from Larry Zoeller Forge.