Propane gasser up and running & some questions.

[Michael]

Been working hot metal in the backyard for close to a decade, now, just about a year after getting my hands on an empty Freon tank, I put together this gasser

which will, hopefully, allow some quick blacksmithing as time permits, instead of the several-to-many- hour commitment that lighting up the coal forge in a suburban neighborhood entails. I’d plan a day off from work and smoke up the neighborhood while the neighbors are away .

Lots of help from Ron Reil and Larry Zoeller's web pages,

I added a sheet metal choke to the burner

 

as well as a quick connect fitting so the propane hose can be removed when the forge shuts down. This is the cure firing for the first coat of the ITC-100.

 

The legs are offset to counter the weight of the burner. I planned the front opening to be one firebrick high, so I can use a stack of bricks as both porch and doors. Back door is a scrap of kiln shelving in L shaped brackets. Forge floor is a more kiln shelving. After some really, quite obsessive, checking for gas leaks with soapy water, it would appear that all is tight.

 

Questions, I only did one coat of the ITC-100 over the Kaowool, are multiple coats advisable?

 

Connections, there's an adjustable regulator at the tank, and a ball valve and quick connect between the hose and burner. For safety's sake would another ball valve after the regulator be overkill? 

 

If I was thinking of adding a gas grill pushbutton igniter. Where on a Reil style burner do you add one of those? or is this a bad idea with this design?

 

Last question, the hi temp BBQ paint is fine when the forge is running, but after shutdown the heat rising out of the door blisters all the paint off. I guess the dragon's breath is pushing way past the door instead of just rising. Is this par for the course with a gas forge?

 

The build has been a lot of fun, especially the push over the Labor Day weekend to tune the burner line the Freon tank. The family kept wondering about the burner roar coming from the backyard.

[Frosty]

I can't say about installing the igniter I'd have to experiment myself. What I do know is you don't want it far enough towards the end it takes too much heat.

 

How long is the burner tube? Yours looks awful long to me. The basic ratio is 8-9 x the ID. So a 3/4" dia. tube should be between 6" and 6 3/4" long give or take a little. and a 1" tube should be between 8" to 9" long, not counting the flare.

 

Frosty The Lucky.

[WayneCoeArtistBlacksmith]

Read the tutorial on my web-site at the Forge Supplies page for some tips.  I suggest that you cast over the blanket then apply the Infrared reflective coating.  Don't fire the forge until the casting is completely cured.  The Infrared coatings have no strength and will get holes poked in it every time that you touch it with a piece of metal.

[Michael]

Well, my burner is way too long, I think 3/4 by 12 was the only pipe nipple in stock, so I cut the threads off one end and went with it.

 

Thanks for the right ratio Frosty. This forge will be easier to store with a shorter burner.

 

Is the extra length adversely effecting the flame? It gets nice and hot, but there's a lot of dragons breath that I can feel, if not see (was using it in bright sunlight)

 

I've read your site Wayne, love that big clamshell forge design that can be propped open with bricks.

 

This one is maybe 7 inches wide, 12 deep and 6 inches high inside, an improvement over the 4x3x6 inch mini MAPP gasser (since passed onto another tool guy a little farther up the smithing slope).

[Frosty]

Yes, too long a tube will reduce entrainment due to friction back pressure. reduced entrainment can indeed result in a rich burn and excesse dragon's breath. Feeling dragon's breath? How can you tell the kiss of a flame from say 2,000f exhaust gasses that are no longer burning? Fire it off at night or against a dark  background and shoot a couple pics so you'll actually KNOW how much dragon's breath there is. A little is a good thing but too much is excess CO which is a B-A-D thing.

 

Your forge chamber is around 500 cu/in which is a little large to bring to welding heat with one 3/4" burner. The general rule of thumb is one ea. 3/4" burner per 300-350 cu/in volume.

 

What do you consider "nice and hot"? If it's hot enough for you then you're golden.

 

Frosty The Lucky.

[Michael]

Here's a shot of the exhaust I'm getting at fairly low pressure (bottom end of the regulator adjustment, no gauge) and with the front and back "doors" (bricks) wide open.

This is after taking a good 4+ inches off the burner tube.

 

Of course, If I increase the gas pressure the breath is correspondingly increased as well.

 

Need to make some longer pickup tongs for pulling small bits out of the forge, I find myself working longer bars than I do in the coal forge,  as the steel a foot in front of the forge gets pretty hot from the front door exhaust.

 

I've never had much luck welding, so the forge getting 1/2 inch square hot within 3 minutes from dead cold is hot enough for now. I can see some tweaking as this gasser gets used. 

 

No one, it seems, builds just ONE gas forge.

 

Appreciate the tips and info Frosty.

[Frosty]

I'm happy to help Michael. The dragon's breath from your forge is blue, it looks to be lean to me. Is the steel scaling INSIDE the forge?

 

Ideally the dragon's breath should have flames tinged a little orange at the ends. NOT a lot of orange or heavens forbid yellow and fluttery. Having a reducing atmosphere in the forge keeps scale from forming IN the fire and makes things like welding much easier. however the downside side of a reducing fire is increased CO formation so the need for good ventilation is much  more important.

 

Having a too lean fire doesn't mean no CO is forming but it does increase the NAO2 and other noxious fumes. Breathing exhaust gasses is a BAD thing. Ventilate!

 

Try choking it down a little at a time till you get a BIT of orange tertiary flame in the dragon's  breath.

 

Another thing you can try is aligning the burner differently. A lot of guys like the burners aimed directly at the far wall/floor/etc. My burners are aimed straight down at the forge floor. However, a lot can be said for angling the burners so the fire rotates in a vortex in the chamber. This makes for a much more evenly heated chamber and reduces back pressure on the burner itself, increasing entrainment. It also keeps the fire IN the chamber where you want it a little longer.

 

Build just one forge? <puzzled look>

 

Frosty The Lucky.

[Dodge]

Frosty beat me to it, but yeah; blue is lean. It will get "nice and hot" but steel will scale like crazy as well

[Michael]

Thanks for the info guys. I'll try choking the intake  and go for just a bit of orange in the dragon breath.  I hadn't noticed a lot of scaling but looking at the couple of leaves I knocked out they are a bit flaky.  I know levels of oxidizing/neutral/carburizing in a coal fire but the lean/neutral/rich in a gasser is not so familiar.

 

This is all new to me so the opinions and insights are of great value.

 

Already planning the next burner with a screw down axial choke.

 

Never had much luck with getting a swirling flame off this or my prior MAPP gas burner. I wonder if that's easier with a blown burner?  Hot spot is nice for a lot of work.  A couple of scraps of kiln shelf on the forge floor, so the heated stock is raised off the floor just a bit, really help in getting the tongs on smaller bits.

[Frosty]

Making a vortex in the forge is just a matter of aiming the burner tube to be more tangential to an inside wall be it square or round. I mentioned it not because it's necessarily superior but because it might relieve back pressure on the burner.

 

My burners are aimed perpendicular to the floor because I LIKE more localized heat and propane forges are NOT known for localized heat under any circumstances.

 

When you start adjusting the choke do it one step at a time and by measured increments. Taking notes is a really good idea so you know what you did two or three adjustments ago and what the effect was. After a while you'll get to know propane burners and be able to adjust them by eye and ear, just like the old school mechanics tuning a car.

 

Frosty The Lucky.