New forge build coming together

[Frosty]

Not quite Mike. Space around the burner in the burner port is exactly the same as the gas jet in the mixing tube and induces a flow of air drawn by the flame. If there is enough pressure in the forge to force flame back out around the burner then it's high enough to inhibit burner induction and function. That or it's a really large space. 

Make sense?

Frosty The Lucky.

[MotoMike]

Frosty

I appreciate you taking the time to try to hammer in understanding.  Not getting it Frosty.  when I built mine I noticed steam or smoke exiting the space between the burner and mixing tube I suspect from moisture or some chemical from materials I used flashing off.  This caused me to pack that space with kaowool and rigidize it.  

I get your analogy Frosty but would submit that it is not the same as the jet sucking in air for a couple reasons, one because it is expanding like crazy at the exit owed to the heat.  additionally, it is located at the output. the flame has no tube in which to create a vacuum to suck in air.  It is the traveling down the tube where the magic happens, no?   if the jet were located at the bottom I don't think it would work as intended.   e    I'll allow it might be so, but still hard to get my head abound.  

Saying it is so, wouldn't packing the space as I did solve the problem if that is where  the extra air  comes from?   And if that is not where it is coming from, how does increasing the bell size correct the issue and in fact not make it worse?

 

 

 

[Frosty]

The steam you see is probably moisture evaporating out of the liner and to be expected.

Next time you have it running and up to temperature light a match, stick or roll of paper blow it out and see what a LITTLE smoke does around the burner. If there's a gap and it isn't drawing outside air your burner is probably too deep in the liner. 

Your logic regarding pressure differential makes intuitive sense but is flawed. If psi were all there was to it then the gas jet in the burner being at much higher pressure than the air in the burner should blow in all directions. Yes? 

The propane jet or flame is in motion and like a truck passing you there is low pressure zone next to an behind it coupled to the thing inducing it truck in the example. Containing this coupled low pressure zone in a tube with ONE outlet and one or more inlets leading from one to the other is what makes induction devices work, linear, jet ejector or air mover.

I have to go to the store, I have a list and time's a ticking. Back in a while.

Frosty The Lucky.

[MotoMike]

We'll have to wait till my next maintenance cycle to see on the smoke from a piece of paper as that space is well packed and rigidized  so I don't think there is a path.   I think you are making assumptions about my assumptions.    I don't think it is all about psi.  for the venture effect to take place, I'd think we need a venture.  the  small distance that the burner sits up in the cavity and the cavity itself, might be such a venturi if a lousy one.   that could possibly explain the intake of smoke from the space between burner and mount. 

Perhaps you or someone else can make a suggestion on an authoritative text on the subject.  

Still this is academic and doesn't address how a larger intake will improve the situation.  

We'll chat later.  

 

[Mikey98118]

14 hours ago, MotoMike said:

Mikey, can you expound a bit on the flame causing scaling?  I was operating on the assumption that scaling would be caused by an oxidizing atmosphere and thought also that a bigger inlet bell would increase the oxidizing nature of the atmosphere.  here to learn.  

A flame is a chemical reaction between oxidizer (in this case about 20% of the atmosphere) and a fuel source (propane in most gas forges). Heat and secondary gases (byproducts of combustion in the primary flame) are the ORIGINAL results. If the primary flame envelope doesn't perfectly combine fuel and oxidizer one of the gas molecules blown forward within your forge ( usually straight toward your superheating work pieces) is superheated oxygen. Note the stress placed on super heated work surfaces and also superheated oxygen molecules; that's because heating these two factors increases chemical combination of them into scale (oxides of iron).

giving a few extra inches for escaped oxygen to combine with secondary gas from incomplete combustion (carbon monoxide) reduces the amount of superheated oxygen that impinges on work surfaces. Of course the presence of more carbon monoxide in fuel rich flames also help "scavenge" oxygen from exhaust gases before it can reach your work; the question of how much is just right, or is too much is an ongoing debate...

You are correct that an oxidizing flame will contribute heavily to scaling, but we are talking about the same result, scaling, from two very different problems 

[Mikey98118]

A bigger inlet bell will help induce more atmosphere, and so it is conceivable, but not very likely, for this improvement to help contribute to scaling, but only if other things on your burner are way out of whack. Why? Because a larger bell only makes it easier for the gas jet to induce air into the burner opening; it is a passive factor; not an active one. A rich or lean flame while usually result from the diameter or the gas jet's orifice being to small or large in comparison with the burner's mixing tube diameter.

As a bell reducer or cone shaped air inlet's large opening increases size in proportion to a given mixing tube diameter, the strength of the vortex it creates also increases. The resulting advantages of vortical flow that then increases with it is what make a large bell reducer such a major advantage on linear burners; it isn't a question of gathering air from a larger area--that is irrelevant.

[Mikey98118]

13 hours ago, Jimmies said:

What is it that you are descriving as the tertiary flame....what part of the flame am i looking for?

I believe it was Frosty who first named them "tertiary"; what are they? They are a third flame envelope. Tertiary flames are purple, large, and ghostly; sometimes you have to look hard to see them in flame photos; They are a third flame envelope; always the outer envelope when they are present at all.

Sometimes a beginner will only see two flame envelopes and say aha! How can a secondary flame envelope possibly be called tertiary?!? It can't, but the answer is that you have failed to detect the two flames inside the 'first' envelope. Sometimes people will see a white flame with a blue envelope around it and think it is a single primary flame. Wrong; the white flame is the primary flame and is surrounded by the blue secondary flame. Sometimes a lighter blue or blue-green flame will have a thin darker blue "edge" surrounding it. Once again you are seeing both primary and secondary flames. Sometimes blue-green or lighter blue flame will be interspersed with darker blue flames in a patchwork quilt of primary and secondary flames. What all these flames will ALWAYS have in common is a tertiary flame envelope surrounding them, and pushing out ahead of them; it may be strong and large, or faint and small in comparison with the other two envelopes, but it will be there.

What then is the tertiary flame? It is escaped superheated oxygen and carbon monoxide molecules that are either combining with secondary air in the forge or else being expended out an exhaust opening. 

[Jimmies]

Well I've given it a good warm up and these are the first three things I have every forged, 

Bent a nail....then a bad leaf....then a better leaf.

 

 

[MotoMike]

Mikey  thanks for the detailed explanation.  food for thought.  

Frosty thanks for trying to get through to me.  Hope shopping went ok. 

Jimmies  Good Job.  Your second leaf looks better than my 5th.  

[Jimmies]

This is the flame earlier when I had a good heat in the forge after 10mins of ignition. I've yet to run it at full whack yet...this was it at around 2 or 3 psi

[Frosty]

Mike: Tertiary flame is from a gas welding and cutting text book from shop class. Learning to adjust oxy acet torches in shop is how I learned to tune a propane air burner. Differences of course but fundamentally the same thing.

You're right Mike I did make a false assumption about your question and explained something else. With the burner port packed it can't be drawing enough air to effect the forge atmosphere. Even if air can pass through blanket it requires more psi differential than exists in this situation.  I really gotta pay more attention to questions before hitting the keys.

Jimmie: You're striking with the corner of your hammer to get that texture on the leaves. It's just a matter of gaining better hammer control and you'll be using the edges for texture. I use both hammer edge and veining chisel on leaves, depends on how I feel, want or what the customer likes. I gotta say though, I really like that corner strike texture, a little refinement in placement, spacing, etc. and it'll be a REAL useful tool in your mental tool box.

For example, applied point down in overlapping rows and you have pointy scales. Hmmmm?

Frosty The Lucky. 

[Jimmies]

Hi Frosty

It was the edge of the cross pein that was making those marks...and yes it was completely by accident. In fact I was going to ask if I should round off the edges of the pein to remove the errant strikes...but I guess as you say once I start to learn some control it will give me more possibilities of texture 

[Frosty]

Yes, round the edges of your hammers, its called dressing and makes a BIG difference. All my hammers are dressed: edges rounded, peins curved and rounded and faces slightly crowned. Crowning means it's SLIGHTLY domed so it makes fuller contact. 

When I need a truly flat tool or sharp edges, corners, special shape, etc. I use a flatter or make a punch, or various top tools to suit.  There is a world of tools for shaping hot steel to our desire. 

Frosty The Lucky.