Newbie needs help with burner behavior

[EnglishDave]

Hi

I have just lit up my small home built gas forge for the first time. It is firebrick lined with refractory cement lined with Metrikote. There are some flaking issues with the latter but that is not my question here.

I bought the burner online from what claims to be a blacksmithing school here in the USA who make them to help support their business so I figured it was a safe option.

I had lit the burner for a few minutes and it was 'on' and there was blue flame visible through the 'ports' you can see high up near the gas connection and a nice roar but the flame coming out of the business end was almost invisible and did not seem to be generating huge heat. I tried heating some very thin stock and it got hot but nowhere near orange heat. Suddenly, and for no obvious reason I could see, the flame 'switched on' and became a roaring pale blue jet projecting down inside the forge chamber. This brought my stock to red heat in a matter of seconds. I then put in a thicker piece (about 1/2 inch square, some sort of small pry bar) and that was at red heat in very short order. 

I would love to know what changed and how I can get that flame back, I turned the gas off and then lit it again and I was back at the low heat flame, playing with the propane regulator did not seem to make any difference. The burner itself has no adjustments I can see apart from how far into the chamber the end projects (at the moment the end is probably 3/4 inch inside the firebrick - should it maybe be nearer the inside surface of the forge?)

Looking forward to any suggestions, I want that flame back

Pictures of the burner and the forge in use attached

Thanks
Dave

[Frosty]

You lit it in the wrong place. You need to light it at the output end of the burner not the air intakes. Or maybe the pressure didn't come up fast enough to prevent it burning back into the burner. Back fires aren't a good thing and worse they don't make heat where you want it, in the forge.

Wad up a small piece of paper, light it and toss it in the forge chamber then slowly open the burner valve.

Of course these burners don't come with proper valves and rely on the tank valve, using the regulator is a BAD way to turn the fire ON and OFF. Till you get a proper shut off valve, leave the regulator  at a good operating setting and turn the tank valve FAST. When you shut the tank valve off do NOT crank it off hard, that damages the valve seats and makes them leak, just firm is plenty hard enough.

If you buy a 1/4 turn ball valve rated for propane and install it between the regulator and the hose you're set to go. This gives you a valve that's just an on off valve and is quick to close in an emergency. Putting it at the regulator means that in an emergency you can turn the flame off without getting too close to the fire. Having to turn off the gas flow with the tank valve in an emergency can get hairy quick. The window of opportunity to control a bad fire before it's completely out of control is short, often a matter of seconds. If you can get on it fast enough you might, MIGHT be able to get it under control and out. Propane forge bad fires usually have a pretty wide window but if you can't get it done in time the results of an out of control propane fire can be disastrous, including explosions and shrapnel the neighborhood will talk about for a generation or two. 

My preference in 1/4 turn valves are the ones with long single handles, the handle position is easily visible from across the shop and if necessary I can just swat it with a rag or thrown glove to shut it off. The valves with T handles work fine they're just not as good a panic shut off. That's just my opinion and preference of course.

Frosty The Lucky.

[EnglishDave]

Frosty, thank you for the response. I have been lurking in this forum for a couple of weeks and your name pops up more often than most and you usually have something constructive and knowledgeable to add from what I see so I am very glad you have chimed in on this one.

You are spot on, I was lighting it at the intakes

I shall head outside right now and give it a try lighting it at the correct darned end lol

Also hearing what you say about the cutoff valve makes sense, I will get my hands on one asap.

I am so excited that the forge did work at all, once the flame was the right variety man did it heat that stock up fast

Once again thanks for the input, this is a great forum.

Dave

[EnglishDave]

So now it lights correctly and runs fine for ten-fifteen minutes then starts to huff and puff and eventually the flame goes out inside the forge body and relights back up inside the burner. I have tried adjusting regulator up and down while it is doing this and no conclusive results.

I read on here where you give a length:diameter ratio for a a burner and mine is way too long according to that formula, I am at work right now and do not have the exact measurements but from what I recall mine is around 3/4' inside diameter and about 9" long from jet to orifice, should I cut some length off it?

[Buzzkill]

How close to empty is your propane tank?  If you're using fuel fast enough to cool the tank then you may get a drop in pressure and it won't matter how far you turn up your regulator.  A simple way to see if this is the problem is to place your propane tank in a shallow water bath.  You just need enough water to make good contact with the bottom of the tank (not the ring it sits on).  If you do that and the problem goes away then that's your cure or you can link 2 tanks together.

[AnBello]

From the photos it seems that it's ok, but just in case:

Is there a big gap between the burner and the forge? If there is, exhaust gases (with no oxygen to light the flame) might be going up and getting into the intake.

[EnglishDave]

1 hour ago, Buzzkill said:

How close to empty is your propane tank?  If you're using fuel fast enough to cool the tank then you may get a drop in pressure and it won't matter how far you turn up your regulator.  A simple way to see if this is the problem is to place your propane tank in a shallow water bath.  You just need enough water to make good contact with the bottom of the tank (not the ring it sits on).  If you do that and the problem goes away then that's your cure or you can link 2 tanks together.

It is now about 1/4 full but it has been doing this all the way from full I think, I will try your water bath idea though, easy enough to test thanks

50 minutes ago, AnBello said:

From the photos it seems that it's ok, but just in case:

Is there a big gap between the burner and the forge? If there is, exhaust gases (with no oxygen to light the flame) might be going up and getting into the intake.

Not a big gap, maybe 1/16 or less in places. I had considered blocking that up with some spare kaowool maybe, will try that out tonight also. Thanks

[Ricko13]

Hello folks,

Just so happens I got a forge with a very similar burner today. Upon looking at it closely I found one of the fittings was double threaded and crooked... so I'll be replacing that.

Until then I won't light it up, but I'll pay attention to this thread to see if you get any progress EnglishDave.

Cheers,

-R

[EnglishDave]

So I filled in the small gap between the burner collar and the forge body with some refractory cement last night. That should be fully dry in a day or two and then I will fire it up and see how it goes, will update this thread once I have some news.

Thanks guys

[Frosty]

How deep into the liner is your burner positioned? What you describe sounds like it's overheating to me. A 20lb. propane bottle tends to ice up pretty quickly which matches the symptoms as well.

Frosty The Lucky.

[EnglishDave]

10 minutes ago, Frosty said:

How deep into the liner is your burner positioned? What you describe sounds like it's overheating to me. A 20lb. propane bottle tends to ice up pretty quickly which matches the symptoms as well.

Frosty The Lucky.

The burner projects about 1 1/2 " down inside the firebrick, it is adjustable via a collar so once the cement I used to fill the gap has set I can play around with varying the amount of the burner pipe which is inside the forge lining. No visual sign of the propane bottle icing up that I have noticed but I have not touched it during use to notice how cold it is getting.

[Frosty]

Try pulling it back so it's only maybe 1/2" inside the brick. Part of what's happening is the flame is heating the brick where it exits the burner and 1" of brick will radiate more than enough IR to over power the cooling effects of the fuel air mix.

If your tank was icing up condensation would be frozen to the outside well before propane begins to slush up and the psi falls off.

Frosty The Lucky.

[EnglishDave]

10 hours ago, Frosty said:

Try pulling it back so it's only maybe 1/2" inside the brick. Part of what's happening is the flame is heating the brick where it exits the burner and 1" of brick will radiate more than enough IR to over power the cooling effects of the fuel air mix.

If your tank was icing up condensation would be frozen to the outside well before propane begins to slush up and the psi falls off.

Frosty The Lucky.

Roger that, I will be lighting up tomorrow and let you all know.

[Latticino]

Personally I would contact the group you purchased it from to help you with tuning before making any major modifications.  That being said, I see some potential issues:

• The location of your burner allows the forge heat and exhaust fumes to rise back up towards the burner (I prefer side entry burners for that reason).  One could cause pre-ignition in your burner mixing chamber (does the burner mixer get very hot after it runs at correct working conditions?).  The other could cause a flame-out condition by starving the burner of oxygen due to the induction of flue gasses rather than "clean" air.
• When you adjust your burner operation you will most likely have to adjust both the air and propane (using the inlet shroud for air and the regulator for the propane).  It sounds like you are just adjusting the propane.  At what you see as correct operation do you have a reducing flame (some "dragon's breath" exiting the front of the forge)?  For most operations that is the target.
• I've built a similar type propane burner.  During initial tuning, which took place outside the forge body, the location of the gas orifice and specific location of the SS flare on the end had a lot to do with maintaining a stable flame.  It appears that you can adjust the orifice location with the set screws in the side.  The flare on mine made small variations in the burner mixer length.  I was quite surprised at how sensitive the assembly was to small changes in that length.  Might be worth investigating with the vendors.
• Pressure variations in the gas can totally screw with the operation of a NA burner.  So can any debris that occludes the orifice.  A gage on the regulator is always a good idea IMHO, and a loupe can help you check the orifice (or maybe just some properly sized music wire).

[EnglishDave]

On 3/31/2017 at 8:24 AM, Latticino said:

• When you adjust your burner operation you will most likely have to adjust both the air and propane (using the inlet shroud for air and the regulator for the propane).  It sounds like you are just adjusting the propane.  At what you see as correct operation do you have a reducing flame (some "dragon's breath" exiting the front of the forge)?  For most operations that is the target.

When you mentioned 'inlet shroud' a big light bulb went off in my head and I have realised that you may be referring to the movable collar located up near the top of the burner? There were no instructions at all included with the device and I assumed that was just a mounting collar to allow me to vary the overall position of the burner up and down relative to the forge - you can possibly see where I have it in the picture of my forge above. Are you implying it should actually be partially covering the inlet holes and is adjusted to vary the air/fuel mixture? Wow, if so I have used it wrong and need to make a new one.

[Mikey98118]

Don't overlook the gas connections near the gas jet orifice; a loose part there can create a lot of trouble.

[Frosty]

5 hours ago, EnglishDave said:

When you mentioned 'inlet shroud' a big light bulb went off in my head and I have realised that you may be referring to the movable collar located up near the top of the burner? There were no instructions at all included with the device and I assumed that was just a mounting collar to allow me to vary the overall position of the burner up and down relative to the forge - you can possibly see where I have it in the picture of my forge above. Are you implying it should actually be partially covering the inlet holes and is adjusted to vary the air/fuel mixture? Wow, if so I have used it wrong and need to make a new one.

I'd call it a choke rather than inlet shroud though, it certainly describes it's function so I guess it's a valid term. 

The reason these burners don't come with good tuning and operating instructions is because the guys making them don't really know what they're doing or they'd be making the burner differently.

These burners work so don't feel ripped off, they could just be much better.

Frosty The Lucky.

[Hammerfall]

I bought the same burner off of EBay. Adjust your slip collar. I had the same issues. Now it works fine. It does take some play to figure out.

[EnglishDave]

8 hours ago, Hammerfall said:

I bought the same burner off of EBay. Adjust your slip collar. I had the same issues. Now it works fine. It does take some play to figure out.

Since I have now cemented that collar in place into the top of the forge itself (thinking it was for holding the burner tube) I think my easiest option is going to be to fabricate a new one, after all it is just a metal sleeve which has a set screw for holding it in place. Looks like I need to make stuff before I can make stuff this morning 

[Irondragon Forge ClayWorks]

2 hours ago, EnglishDave said:

 Looks like I need to make stuff before I can make stuff this morning 

Welcome to the world of Blacksmithing, gotta make stuff (tools) to make other stuff.

[Frosty]

3 hours ago, EnglishDave said:

Since I have now cemented that collar in place into the top of the forge itself (thinking it was for holding the burner tube) I think my easiest option is going to be to fabricate a new one, after all it is just a metal sleeve which has a set screw for holding it in place. Looks like I need to make stuff before I can make stuff this morning 

Ayup, make the tools to make the tools to make the goods is why blacksmiths were so often the birth and death of communities. 

Frosty The Lucky.

[EnglishDave]

I have always been a woodworker but branching out into iron and steel adds a whole new dimension, I love it.

I made a new collar out of some copper sheet and soldered it into a cylinder to replace the choke sleeve, hoping it should not get so hot as to melt the solder but if it does hey ho more excuses to fabricate stuff 

[ThomasPowers]

I think the two things that impacted the decline in Blacksmithing were: the factory and the railroad.  I was reading that it became cheaper to buy wagon wheels from a catalog and have them shipped halfway across the country than to have a local craftsman make them for you. (And may have been faster too.)

[EnglishDave]

So I filled up my propane tank and also placed a couple of bricks on the top of the forge as some sort of deflector so try and guide and exhaust gases coming out the front away from the burner inlet. The whole forge is open ended so I can turn it round and run it the other way which would position the burner towards the rear rather than towards the front, that may also help a little with keeping combustion gases away from the inlets.

Working pretty well so far today but have other chores to do before I can play any more 

2 minutes ago, ThomasPowers said:

I think the two things that impacted the decline in Blacksmithing were: the factory and the railroad.  I was reading that it became cheaper to buy wagon wheels from a catalog and have them shipped halfway across the country than to have a local craftsman make them for you. (And may have been faster too.)

Which probably goes for most manufactured goods today, not to mention much of our food.

[Mikey98118]

Back before I became a doddering old man, I used to love combining craft materials, such as wood and iron, or glass and iron. BUT, sawdust and and flame are a total no-no. Hope you are being careful to keep all flammable materials well away from your forge.