[TheForge] Burner types was Fixing my forge

Fri Aug 10 04:42:48 EDT 2007

Jerry

Thank you very much I now have a understanding. I have a burner that I 
built and from your description I built 'jet Ejector' type. I think. 
Just one last question to clarify. The jet of gas is it up stream of the 
air intake for the jet ejector type? It look like this to me and that is 
the way that I built my burner. I have seen some that it looks as if the 
jet is halfway up the air intake. I have seen the type of burner that I 
built described as an upwind burner.

Thank you again for the time you took to explain the burners to me. I 
really appreciate it and all the other folks on this list thank you.

Kind regards
Geoff

Jerry Frost wrote:
> You bet. <grin>
> 
> What we use for naturally aspirated burners are induction devices in the 
> commercial world. They operate based on bernoulli's pinciples rather 
> than Venturi's. Basically a jet of high velocity gas, liquid or mist 
> will draw another gas, mist or liquid along with it. Placed in a 
> confined space of the right shape and it will induce quite a bit of 
> movement from the ambient atmosphere.
> 
> There are two (of many) types of devices that will induce ambient air in 
> a burnable ratio; these are the only two that are useful for forge burners.
> 
> The first type is known as a "linear" inducer. The jet and air intake 
> are inline with the tube; you can look into the end and see right 
> through it if there isn't a choke, etc. blocking the intake end. 
> Examples of linear inducers are the: Bunsen burner, Aussie, Reil, etc.
> 
> The other applicable type is the "Jet Ejector". The jet and air intakes 
> are at 90* to each other; looking up the tube you'll see th end of the 
> jet but the air intakes will be in the sides so you can't see through 
> it. Examples of "Jet Ejectors: are the: Fisher burner, Porter, Rex, Side 
> Arm, and "T" jet.
> 
> A commercial linear inducer using gas on air has a max induction rate of 
> around 19:1. (the ratios of induction are different if you use a liquid 
> to induce a gas or visa versa, there is an entire industry devoted to 
> designing these things for specific applications.) A neutral ratio of 
> air to propane is 17.5:1. So you can see you have to make your linear 
> burner to a pretty high degree of accuracy to produce a neutral flame. 
> There are a number of tricks to adjust the ratio so don't worry, they 
> will work just fine.
> 
> A comercial Jet Ejector using gas on air has a max induction rate of 
> around 29:1 (I'll fess up, I don't know if "Jet Ejector" is the correct 
> term for this type burner. I use it because it's the term used in the 
> information I was given some 15 years ago) As you can see using an 
> inducer with a max rate of 29:1 means you have a lot of tolerence to 
> play with; in other words you can fall far short of ideal and still have 
> a good neutral flame in you furnace.
> 
> I have ZERO idea of why a jet ejector is nearly 50% more efficient than 
> a linear. I've never even tried to find out. While I'd be intereted in 
> knowing, it really isn't important, I use the things and they work dandy.
> 
> Of the many Jet ejector type burners only a couple are as difficult to 
> fab up as a basic linear inducer. A case in point is the "T" jet I 
> built. To build it you need to accurately drill and tap a hole in the 
> top of a "T" fitting so the jet will be aligned straight down the burner 
> tube.
> 
> During the summer of 98' Robert Grauman was visiting Alaska and spent a 
> few days with us. We were in the midst of building the house and I had 
> almost all my smithing gear packed away. Being a caster Robert has as 
> much or more interest in burner design as I do so we spent many 
> delightful hours talking about HOT fires and glowy metal. It seemed 
> Robert understood exactly what I was describing so I didn't dig out my 
> "T" jet burner to show him nor did I make a sketch. A few months later I 
> got an E-mail from him with a few pics of his burner in operation.
> 
> I almost sent a reply saying he'd screwed up because he hadn't built 
> what I'd described. He'd built the Side Arm. Fortunately I came to my 
> senses and didn't say something so dumb. He did send pictures of his 
> burner in operation, including the bronze pouring merrily into the mold. 
> <grin> Later on I confessed my near stupid statement to Robert and he 
> told me he understood exactly what I was talking about but it seemed 
> more trouble than necessary and experimented with turning the "T" 90*.
> 
> The Side Arm is a lot easier to build than the "T" jet unless you have a 
> lathe. The only drawback (and it's slight) to the Side Arm is tuning it. 
> The air intake is all on one side so you have to aim the jet slightly 
> into the intake stream to keep everything flowing straight down the 
> center of the tube.
> 
> When I get my shop finished I'll start experimenting with burners again, 
> the "T" I'm using is at lest 15 years old now and I think I can do 
> better. <grin> The next real change I'm making is to use a "Cross" 
> rather than a "T" so a person doesn't need a lathe or jig and drill 
> press or a really GOOD eye with a drill to align the jet properly. A 
> write up of the "T" jet burner will be appearing in an upcoming issue of 
> the Hammer's Blow; unless Brian comes to his senses in time. <grin>
> 
> There are any number of configurations for a jet ejector, Mikey's being 
> one of the best of the home made ones out there. The basis of his design 
> is a straight tube with longitudinal slots cut in the back. (The end 
> with the flame coming out being the front for the puposes of discussion) 
> His gas jet can be mounted in any number of simple ways as long as it's 
> aligned straight down the center of the tube.
> 
> Anyway, there are a lot of options; some simple to build and harder to 
> tune, some harder to build but simpler to tune and some in between. 
> Hopefully I didn't completely muddy the waters for you but if so, I'll 
> be more than happy to toss a little more clay in the waters. <grin>
> 
> Frosty
> -------------------------------
> If it ain't forged
> it ain't real.
> Wrought iron is.
> The FrostWorks
> 
> Meadow Lakes, AK.
> 
> http://www.artmetalradio.com/
> 
> From: "Geoff" <gjn111 at gmail.com>
> 
> 
>> Hi I am normally a lurker but I realised from this that I have no idea 
>> what you wrote here. Jerry can you please explain in a bit more detail 
>> what the major differences are between the two types of burners that 
>> you describe. And can you please help me understand how the efficiency 
>> differs.
>>
>> Thank you in advance
>>
>> Geoff
>>
> 
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