Venturi Burner Concerns

[Shepdog]

I've fabricated a couple of burners out of pipe fittings, Reil style, .035 mig tips, 6" x 3/4 main pipe with a 1" nipple as a flare into a tank-style forge.   First run, wasn't getting enough air.  Drilled some intake holes in the main pipe, pretty much even with where the MIG tip ends...

 

here's my question/concern:  runs like a champ at around 5 lbs pressure, but any lower, and the flame starts coming out the intake.  I've seen other burners where the end of the tip is visible through the intake holes/slots...do I have to move the intake holes back?  Do I need to worry about imminent death/disfigurement if there is a bit of flame coming out of the intake holes?  

 

appreciate any feedback, this build is really for my 12 year old son who is totally enamored with the idea of forging, so hey, if it ain't an xbox, I'm all over it.

[DSW]

Welcome. Glad to have you here with us. Take a minute to add your location to your profile so we know roughly where you are at. You might be surprised how many here might be near by.

 

I'll leave the burner question to Frosty and some of the others who have more experience with gas forges than I do. I do congratulate you on finding something that interests your son and keeps him away from video games. Forging can be a great amount of fun for both of you. I think it's a shame more young kids don't learn to do things with their hands these days.

[Charlotte]

There are several things wrong with your build from start to finish but...Your own creative design finally pulls enough air at 5 psi and has enough velocity (kinetic energy) and volume of gas to over come the restrictions  in the system. I suggest you search for Frosty T-Burner  in the search system or even read some of the stickies posted here,

[Buzzkill]

I asked Frosty a very similar question in a private message recently.  I built a new propane forge and a 3/4 inch Frosty T burner to use in it.  Mine burns well down to about 2 psi and then starts sputtering as the flame burns in the tube.  Frosty said some of his start sputtering around 5 psi. If it burns smoothly at 5 psi or more just keep at those pressures.  The propane has to be moving fast enough to pull the air in with it, and there are a lot of factors that can affect the burn from one geographical location to another.  Elevation, humidity, barometric pressure, etc. all come into play according to what Frosty told me. You shouldn't need a flare of any kind with the burner in the forge, but I don't think it hurts anything either.

[Frosty]

Too many people get enamored of irrelevant things like some target low pressure. Ron caught that bug and spent quite a while developing his burner designs till he could run them at low psig. Some guys have taken it as some holey benchmark for burner goodness. Unless you plan on tapering the entire tube length you will NOT get one to operate like a commercial burner.

In truth it doesn't matter a fig in a flood. If you have a clean burn that works then that's it you're done. If it ain't broke don't fix it.

The one real reason to put a gauge on your regulator is NOT to try for some psi someone else runs. The sole good reason it to make repeating forge temperatures fast and easy. PERIOD. There are just too many variables between locations and burner builds for any one pressure to mean anything anywhere but your burner. My shop forge has 4 burners and each performs a little differently.

Then again if you want to go ahead and join in the home built burner PSIing match.

Your specific questions about your burner: #1, that's NOT a Reil burner. #2, NO the jet should NOT be farther down the tube than the air intakes, it should be well above them or it won't induce air worth spit.

Frosty The Lucky.

[Shepdog]

Thanks for the responses...my main concern was safety, but as Frosty said, if it ain't broke....

[ThomasPowers]

And as I've mentioned multiple times:  the psi gauges for cheap regulators can be 50% off; if you have not had your gauge calibrated professionally in recent times please treat it's numbers as "suggestions" rather than laws and this counts for brand new ones too!  Use it to get what works for you 

Now you could almost swap out pressure gauge for pyrometer  in the below poem; but both are applicable!

L.G.Firth (published in Chemical and Metallurgical Engineering 1918)

The Man at the Fire

 

There are some who forget what experience means

 

(They are generally fellows just out of their teens)

 

And by using pyrometers seem to acquire

 

A lack of belief in---

 

“The man at the fire.”

 

They’ll talk of “calescence” and “pearlite” and tell

 

You the value of “cementite”:---(sounds very well!)

 

And the depth of their learning will make you perspire,

 

But they don’t get results, like---

 

“The man at the fire.”

 

A pyrometer’s good when it’s kept in its place

 

But sometimes you’ll find there’s a lie on its face,

 

And then when the heat’s climbing higher and higher,

 

The man who can tell, is---

 

“The man at the fire.”

 

Now do not mistake me; I say, by all means

 

While you’re lacking in skill, put your trust in machines;

 

But if to be really expert you aspire

 

Then study, as well, with---

 

“The man at the fire.”

 

So when you are learning your job, never heed

 

Those who tell you that skill is a thing you don’t need;

 

For skill and hard work you will surely require,

 

If you hope to compete with---

 

“The man at the fire.”

 

 

 

Edited October 8, 2015 by ThomasPowers