choosing a regulator

[Cary Brief]

Hello all, my first post here.  New to blacksmithing although not to metal working - I am a machinist, lost wax and sand caster and a jeweler to name a few.   I am building my first gas forge - the burner is not a problem, similar to ones I use on casting furnaces, going to try out two designs, one I got from Dave Hammer" youtube video and Ron Reil's burner.   My question is how to know what PSI Regulator you need?  I plan to use a needle valve to control my gas flow -    All my casting furnaces have blowers and these don't - that is where I am confused - also On Zoeller's website the single burner setup has a 3-30 PSI reg,    Dave Hammer suggests a 1-60  and lots of what I read here also suggests a MR Heater 1-60.     Just wondering what you experienced folk say about this subject before I go buying anything.   Like I have read here, when I discuss this with the "propane pros" they get all quiet and don't want to say anything.  Anyway thanks for the great group - lots of interesting information here.  Hope I have something nice to show you soon.  

[Frosty]

I run a 0-30. I've never seen a properly made and tuned naturally aspirated burner that needed even 30psig. let alone 60. More isn't better, right is. Forget the needle valve, would you run a string to the throttle to control the  fuel injected engine in your car? A needle valve is just a poor way of doing exactly what the regulator does and it's after the regulator. Really pointless bit of extra stuff to go wrong.

Dave has a pretty well thought out method for building an ejector type NA burner. Ron's are perfectly workable linear type NA burners. Properly built and tuned either will bring a forge to welding heat. Bearing in mind a linear type burner is good for up to 300 cu/in volume if you do a good job of putting it together. An ejector type will do same for on average 350+ cu/in. volume and are less susceptible to breezes and back pressure issues.

Frosty The Lucky.

[Cary Brief]

Thanks Frosty, this is why I asked - I saw so many different set ups (just like in casting furnace propane runs) and I wanted to get it right.  What you say makes sense.  I will post pics once I have it all done.  

[Frosty]

You're welcome. I just noticed I forgot to include the other half of the burner type vs. volume equation, those numbers are for 3/4" dia. tube burners. The effective furnace volume is in direct relation to the area of the burner's outlet tube. Eg. a 1" burner has 2x the area of a 3/4" tube and effectively heats 2x forge volume.

Frosty The Lucky.

Edited April 8, 2015 by Frosty

[Cary Brief]

One more question while I have your attention!   I purchased galvanized pipe parts for my burners, after going to 2 or 3 home depots, Shell Lumber (a huge hardware store - great place btw) and a big plumbing supply - none of them had black pipe at all.   I know galvanized can be used for gas piping, my home gas is plumbed with galvanized - just wondering why black pipe is called for?   again thanks for your help.  Cary

[Frosty]

Just don't use galvy for the burner tube, it gets hot enough to burn zinc and that's not healthy. Our local Home Depot and Lowes both carry black pipe from about 1/2" up but that's here. You might have to go to a plumbing supply or good hardware store.

Galvy is fine for the rest of the set up, supply, air intake end, etc. it shouldn't be getting into the high red heat or something is REALLY wrong! Shut it off and leave the room.

Frosty The Lucky.

[Cary Brief]

I kinda thought that - at least those are the cheapest and easiest parts to find - again thanks.  

[EricJergensen]

Cary,

The zinc will burn off the hot end of your burner. That's not really desirable, because airborne zinc oxide causes zinc fume fever. Airborne zinc oxide generally doesn't form until the zinc melts (787 °F). Even then it doesn't form much until it boils (1665 °F).

[Frosty]

Cary,

The zinc will burn off the hot end of your burner. That's not really desirable, because airborne zinc oxide causes zinc fume fever. Airborne zinc oxide generally doesn't form until the zinc melts (787 °F). Even then it doesn't form much until it boils (1665 °F).

​I know you want to be helpful Eric and don't wish to discourage that but did you not read my reply to that effect? Googling and including specific temperatures isn't much help, who has a thermocouple aimed at the burner?

Frosty The Lucky.

[EricJergensen]

Frosty: note the approximate times on our posts. We cross posted. Yours didn't show (for me) until after mine posted.

I find those temps useful, because they point out that it won't be much of an issue until the metal glows visibly and even then you've gotta get to cherry red or so. Probably should've completed the thought and given colors.

[Frosty]

Sorry, I didn't see the time chop, my bad.

Brazing occurs at mid-high orange and the zinc doesn't burn unless you take it above that. It's not melting temp it's ignition temp when zinc starts oxidizing in a manner to be concerned about.

Keeping galvy out of the fire is safest, you don't need to gauge how hot it's getting.

Frosty The Lucky.

[Little Mac]

Frosty and Eric both have good points . I've worked Iron for a living .And when I was an apprentice I didn't pay heed to the ol boys I worked with and came down with Galvanize poisoning . Body aches in all your joints and you swear you have the flu with a super pounding headache . Bad stuff for sure. Any steel supplier sells black pipe , do yourself a favor and spend a bit of money and a little time to find the black pipe. It might be cheaper than your co-pay at the hospital ! Good luck , work safe 

[Cary Brief]

I took the advice and found black pipe for the burner tubes, however the 3/4 to 1-1/4 bell fitting is galvanized.  Does that matter or does it all need to be black pipe or just the burner tube and as flare?

[Frosty]

Bell fitting? Do you mean a "Bell reducer"? Are you making a Reil type burner? That IS the air intake right? A bell reducer isn't good for a flare on the outlet it's just too abrupt a change in diameter. Heck that's a lot of change for the intake but I haven't messed with a linear burner in a long long time.

If you're using it for the intake end it won't get hot enough to burn the zinc and pose a breathing hazard. You WILL want to block it with a wad of Kaowool or even fiberglass insulation when you shut it down or the chimney effect will draw forge heat up it and THAT might get it hotter than is good.

Another thing you can do is soak the fitting in vinegar and remove the galvy, then you don't have to worry at all. Not even about the people who see galvy near a fire, panic and scream all kinds of . . . things.

Frosty The Lucky.

[basher]

I run a lot of gas forges  (7 currently) and certainly some of them require a 60 psi bar regulator as half of them take more than 30 psi to get to welding heat.

 I think this has more to do with jet size than anything else.

 I would always have a needle valve at the forge so that you are adjusting your gas flow  at the forge rather than the bottle. I keep most of my bottles outside the forge building.

 obviously there are different ways to go about this.

[Cary Brief]

thanks for all the info - Frosty, yes one of the burners I am building is a Reil type and bell reducer - that is it (was late when I was posting too tired to see straight)    I am also building one of the dave hammer burners and see which I like better - do you have a better suggestion of a burner to build?    i will try the vinegar removal today.  any idea how long you need to soak it - I guess just keep checking on it till its gone.   thanks much all

[Frosty]

Ron spent a lot of time refining a linear inducer as a burner and is stubborn enough to not even want to try an ejector type inducer burner.

 Commercially an ejector is around 29% more efficient and several times stronger on the intake. The drainage vacuum truck draws a darned strong vacuum on a 8,000gl. tank with an ejector running 120psi through the jet. It's been known to suck a human body up through the hose and into the tank from a plugged manhole. I wasn't there for that one and am really grateful.

Dave Hammer's burners are a version of an ejector very similar to the one Mike Porter tweaked and wrote his book about. Dave's construction technique is a LOT easier than Mikey's and if properly tuned should perform as well. When Ron and I were noodling the things I settled on the ejector type and fiddled around till I got an easy to build one, the T burner. While I may use my lathe, a drill press is all the special equipment necessary to be easy peasy it to make and tune.

I have a couple linear burners guys Jay Hayes for one have sent me and they work fine but my silly T burners are easier to make and work better. They don't get hotter but the draw is more robust so they're not as effected by breezes and back pressure.

When it gets down to brass tacks how precisely you can build will main determining factor in performance.

Unless you plan on running a couple or more forges in different stations you're not going to need or want to fine adjust individually at the forge, even with multiple burners. If there's much variance in burner performance at the same psi and cant be tuned to perform closely they're not properly built.

The four burners in my current shop forge all got made on the lathe to align everything as closely as possible and one is a golden bullet. That one honestly melts the split 3,000f super duty hard fire brick floor under it, even fresh replacement bricks and it does it at around 23-24 psi. You will get some variation, they're home made, expect it.

Frosty The Lucky.

[Cary Brief]

well I guess I will use the Dave Hammer one !     you know I was reading on another site about casting forge burners with and without flares.   I have a commercially built forge that has a very simple burner - the gas comes in from the side - the air has a blower that flows through a tapered aluminum casting and meets the gas at a 3/4" black pipe - it goes through the tweer - no flare, no tips, nozzles, nothing.    I recently repaired the refractory and coated it with ITC 100 -   and from a cold start got a full crucible of aluminum too hot in under 8 minutes.  used to take almost 20.   would like to build a bigger version for my larger furnace I am working on (21" diameter compressor tank as body.

[Frosty]

That's a gun burner. They're fast and easy to build and only have two down side issues. First you have to have power to run the blower. Secondly if you adjust the heat you have to adjust both gas and air flow. There's a good reason gun burners are so prevalent.

Frosty The Lucky.

[Cary Brief]

thanks for putting a name to my burner - I asked around in other forums, with photos and no one gave it any name at all.  I personally love it - and many casters and blacksmiths have commented on how nicely it operates.  

[yahoo2]

I dont know it it interests you, but if you are in the casting game you might run across someone who sells an amal injector style burner

[markknx]

Frosty,

When you built you injector what size did you drill the orifice? If I recall hammers was .035 mig tip. not sure if there is pros or con to a mig tip. it would be handy, but then again there is a lot of cool to made my own on the lathe. I will be building with a 3/4 pipe, and unless I come up with anything better, and this simple it will be the Hammer design. I will have 300 -350 cubic inches in the forge. Thanks for any input. And the info you gave Cary ( it is helping me also)

Mark

 

[timgunn1962]

The MIG tip is good, primarily because it's easy to change when tuning.

When you are tuning, if the burner is running rich then a smaller gas jet will increase the temperature. It's counter-intuitive and I've had a couple of smiths look at me like I'm an idiot when I've suggested it, but it's true.

If you are running lean, a bigger jet will get you hotter.

I did my fine-tuning with a couple of MIG tips, a thermocouple, a set of micro-drils and a pinvise. Start with a tip that's too small, choke fully open, set a pressure; I used 20 PSI. Measure the temperature. Open out the mig tip with a drill in the pinvise. Do it again. When the temperature reading is lower than the last one, open out the other mig tip to the hottest size and fit it instead. This will give you the widest adjustment range by using the gas pressure and choke.

NA burners use the speed that the gas exits the gas jet to generate the suction to draw in the air needed for combustion. Getting high gas speeds needs high pressures. There is no disadvantage I can see to running at high pressure and I've never understood the "I can weld at 3 PSI" mindset: I much prefer the "I can weld at 40 PSI and Heat-Treat at 3 PSI" idea.