Oil Burner Comparisons for melting Iron (Siphon-nozzle/drip/Ursutz)

Here are some white papers about both pumped and siphon spray nozzles for burners.
Hopefully these things will upload.

Lots of good information about how the fuel is atomized, the shape of the cone produced by the spray nozzle, optimum droplet sizes, etc.

Did I already upload this stuff?
Not sure; age works on the memory, and not in a good way.

Note that this material covers both the Delavan siphon-nozzle, which used compressed air for atomization of the fuel, and pumped-nozzle arrangements which use a pump instead of compressed air.

 

Here is a good pdf white paper.

I am getting an error message "file too big".
I will have to use another method to post it.

 

Yeah some PDFS can't be uploaded here.... :-( David any fix for this?

 

These are the parts of a siphon nozzle.

 

This is not a siphon nozzle (it does not use compressed air), but rather it uses a pump to pressurize and atomize the oil.

I believe that it does screw into the same adapter (shown above) that is used for the siphon nozzle, but the adapter is piped differently (siphon nozzle and pumped nozzle piping diagrams are shown above).

 

There is a good white paper that I like a lot, and its title is "Fuel Nozzles for Oil Burners, Technical Aspects of Applications" by By E. O. Olson, Chief Engineer (deceased), Delavan Fuel Meteing Products Operation, and it contains many discussions such as the pumped oil nozzle, the siphon nozzle, optimum droplet size, etc.

 

Found a PDF downloadable link for that last document by E.O. Olsen:
https://inspectapedia.com/heat/Fuel-Nozzles-for-Burners.PDF

 

Note that the two types of nozzles that people seem to use for foundry furnaces are mentioned beginning on page 9 under "Variable Flow Nozzles" in Olson's book "Fuel Nozzles for Oil Burners".
Everything in the paper before this paragraph refers to a simplex nozzle, which operates at a fixed pressure and discharge rate.

Generally speaking, a spray nozzle for oil burners are used to fire large furnaces/heat exchangers, etc. and so they may use a wide spray pattern to be able to cover a large fire box area.
For a foundry furnace, you don't want a wide spray pattern, but rather a long narrow pattern.

And I use an inline automotive fuel filter when I use diesel, and may add a larger filter ahead of the inline unit if I run waste oil.

He also mentions that the nozzle reaches is maximum temperature after the furnace/burner is turned off due to the radiant heat of the combustion chamber.
A siphon-nozzle burner has an o-ring in it, and the o-ring is cooled by the fuel flowing through the nozzle.
When I turn my siphon-nozzle burner off, I either pull the burner back away from the furnace, or I leave the combustion air blower running after I pull the crucible out of the furnace.

For a nozzle that does not have an o-ring, I think you would still want to either pull the burner away from the furnace or leave the combustion air running, after you turn the burner off, to keep gum from building up in and on the end of the nozzle.

The siphon nozzle can be disassembled and cleaned as shown in the photos above, but I have not had any gumming problems.

 

Good info above, Patj. Thank you.

For the sake of the new Hago siphon tyro wondering just how to actually run such a burner, I will try to provide a verbal visit to my cast iron foundry as one point of view and a place to start. I have now done 40 or 50 burns ususally involving 40 to 55 pounds of iron and have started to feel like the setup is pretty predictable. But I am far from an expert on the subject.

FWIW:

I am using a Hago nominally 0.75 gal per hour SNA siphon nozzle you referenced. It has been very satisfactory to my needs never plugging, gumming, or causing a hiccup. Well, there was the time in the first couple burns that I failed to remove it from the furnace at shutdown and cooked the o-ring. I found a replacement in stock at my local hardware store.

I run it with 12 pounds of compressed air (a simple pancake compressor runs about half the time to provide the needed air) and for combustion use a nominally 20V leaf blower suplied with 12V DC and a damper on it to reduce air flow to about 1/3 of what it would put out undamped at 12V. I use a generic 12V automotive fuel pump to boost Diesel pressure to the nozzle to 4 PSI as elevating the fuel tank for pressurization of fuel was a pain and the pump is dead simple. Like you, I use a simple in-line fuel filter to prevent crud fouling the nozzle though I have had no trouble with that ever.

In that configuration I consistently burn 1.5 gal of diesel per hour. I note the air/fuel stream does not actually visibly ignite until it is a few inches out of the burner tube.

My first burner tube was made of ordinary steel 1.5 inch diameter and held up for about 10 or so 3 hour burns. But the last inch or so gets red hot and gradually it scaled to paper thin. So, I cut off the last 2 inches and tigged on 304 SS tube which probably holds up 3 or 4 ties longer. I would not recommend making a burner tube from plain steel tube for that reason. (Maybe I am doing something wrong to cause breakdown of the burner tube?)

Because the fuel stream does not ignite for a few inches in my setup I do have the nozzle set back from the opening of the burner tube an inch or so to keep it well out of the flame swirl and I keep the burner tube back in the tuyere an inch or so for the same reason.

I ignite with a MAPP gas torch by first starting the compressed air and combustion air flowing and then open the needle valve on the fuel. In a second or two fuel mist enters the furnace and just sticking the torch into the mist results in a solid jet-like rumble and we are off and running.

I don't try to tweak the air/fuel mix for 5 minutes or so to allow the furnace to start to get hot. Then I fiddle with the combustion air damper to get it set so that I can just see a hint of orangish flame licking out the hole in the lid. I used to tune the combustion air a bit leaner and thought I was doing the right thing to have the edges of the lid where flame pushes out show no evidence of soot and look clean and white. I am not so sure that is optimal though as I now think running it a little on the rich side with the flame just a little leaner than smoking results in no longer burn time and produces less dross than a lean flame. This last paragraph is just my own vague observation and may or may not be true.

I secure my tube to a piece of angle iron that acts like a trough holding the tube as it enters the furnace. Wrapped around the tube and angle is a hose clamp that solidly holds the tube in location. To make the clamp more convenient, I silver soldered a t-stem to the clamp screw so that it can be tightened and loosened without tools.

I would welcome suggestions to improve the above described system.

Denis

 

Denis-

I assume you are using diesel for fuel?

I have not played around with waste oil yet, but at some point I plan to start my burner on diesel, and then valve over to a waste oil tank.
Diesel will burn clean without any heavy metal concerns, but I think when burning waste oil, if you stay out of the exhaust stream, and stay upwind of any fumes, you can mitigate some of the risks.
I also have a powered respirator that uses fresh air from inside the house, and I tend to wear that when I am sitting around the furnace waiting for iron to melt.

I have used a standard schedule 40 steel pipe (2" or 2/2.5" dia) for oil burner tubes in the past and that has worked pretty well.
I have since transitioned to using 2.5" dia muffler pipe since that gives a lot more room inside for siphon nozzle with the oil feed elbow, and also gives a larger combustion air flow area.

I like to get the burner set up and aligned with the furnace and plinth inside the furnace so as to minimize impingement of the flame on the crucible, and get the furnace-end of the burner tube slightly recessed in the furnace wall and not protruding at all into the furnace interior

I am not sure why you are overheating the end of your burner tube.
The only time I have seen that happen is when the end of the nozzle is not near the end of the burner tube, in which case the flame can start inside the burner tube and heat it.
The other way to overheat the end of the burner tube is to let it protrude into the furnace.

I put a small lit rag with a little diesel on it in the furnace, and then turn on the compressed air and oil first, and then the combustion air.
I have tried the hand torch light thing, but have burned off a lot of hair off my arm when things don't necessarily go right.

A siphon nozzle that is set up correctly does not need or use much compressed air, and one of my planned upcoming tests is to start the burner with compressed air, and once the furnace gets hot, turn the compressed air completely off and let the burner operate like a drip-style burner.

 

I have not had time to sit down and really trouble-shoot my oil burners, and so my success with melting iron is an on-off affair.
Some days I have great success with melting iron, and other days I sit and watch the iron glow read hot for hours, but never actually melt.

My time always seems to be limited, and so I am always in a rush making molds, dragging equipment out into the driveway, etc, and before you know it, it gets late and I have to start shutting down and bringing the equipment back inside, often before I get things figured out.

I have tried a lot of burner types, including two siphon-nozzles in a single 3" burner tube, two separate siphon nozzle burners each in their own tuyere at 180 degrees apart, single siphon-nozzle burner, drip-style burner, external combustion-type Ursutz burner (similar to this but with round 10" dia steel pipe https://patents.google.com/patent/US2387420), an oil burner made from a spray paint gun, and an oil burner made from a cutting torch tip, which used the center hole for oil and the outer ring of holes for air.

I keep coming back to the single siphon nozzle burner in a 2.5" tube for several reasons:

1. It starts instantly and easily on diesel, and can go to full output in seconds without having to warm up the furnace (not necessarily a good idea for the furnace or crucible, but it can be done).
2. With a needle valve on the fuel line, I can have very fine fuel flow control.
3. By varying the compressed air pressure, the fuel pressure (I use 5 psi or so on the fuel tank), and combustion air flow, the burner can operate across a wide output range; anywhere from perhaps 1/2 gal/hr to 6 gal/hr.
4. A siphon-nozzle burner can easily be used without a combustion air blower when melting aluminum, although I generally always run combustion air just to minimize melt times. A siphon-nozzle burner will self-aspirate just like a self-aspirating propane burner.
5. I don't need propane for pre-heating the furnace when running diesel. Some I think actually start on waste oil if the oil temperature is high enough.
6. I can see the level in my fuel tank via a vinyl level gauge. That is one thing I don't like about propane; I never really know how much is left in the tank.
7. With 5 psi on the fuel tank, the siphon-nozzle burner output never varies regardless of fuel level in the tank (I have a tall tank which was a 100 lb propane tank in a former life). Once I start the burner and make the initial adjustments to tweek the output, then I never have to touch the controls again during the melt.
8. A siphon-nozzle burner operating (or just starting) on diesel works just as well when the fuel, burner and furnace are at 32F than when the temperature is higher.
I experienced very significant problems with trying to melt aluminum with propane in cold-weather conditions, and significant problems with keeping a propane tank warm enough to give enough vaporization to allow for iron melt fuel-flow rates even at 70 F.

 

The problem I have when melting iron (edit: the problem I use to have; I no longer have this problem) is tweeking the controls to get complete combustion of the fuel inside the furnace.

Too much fuel and you have unburned fuel exiting the furnace with, with associated flames.
Moving unburned fuel through a furnace is not heating the furnace; the fuel must combust completely inside the furnace.

I can almost melt aluminum with flint and steel (an exaggeration, but you get the idea).
Melting iron requires a burner with a high output that is adjusted correctly. As ironsides demonstrates in his recent video, this can be a high output propane or fuel-oil burner with a combustion air blower providing sufficient air to combust the required fuel input.

And adjusting an oil burner is highly misleading.
It actually feels like the burner is producing much more output when you have more visible flames coming out the lid, perhaps because you are feeling the radiant heat.
It also feels like you are running a hotter flame when the burner is really roaring, but I think that is like opening the exhaust pipe on your car at the race track; the car sounds like it is doing 200 mph, but it is all noise and no additional speed.

On one of my early iron melts, I adjusted the burner to what looked and sounded like maximum output, only to sit for two hours without the iron actually melting.
I started adjusting the burner, and when all the visible flame went away, and the burner began running much more quietly, the iron actually started melting quickly.
By observation I would have guessed that no flame and a quite burner = low output, but the opposite was true.

So what needs to happen with any burner is that the fuel must combust completely in the furnace.

 

There has been much speculation and heated debate (full-blown burner wars, although not necessarily among those who do actual metal casting, but rather with those who shill burner videos on Y-tube for money).

So what is "THE" ultimate burner type/configuration?
The answer is simple "The ultimate burner type is the one that works well for you with the metal type you are melting".

So lets look at who successfully melts iron regularly in a commercial or potentially commercial setting, and compare the types of burners that they use:

Example #1 (Justin 'scavenger"):

1. Commercial production foundry setup: Yes
2. Number of successful iron melts exceeds 200: Yes
3. Makes and sells (or has at some point) iron castings: Yes
4. Type of fuel: Waste Oil
5. Type of burner: Delavan siphon nozzle oil burner


Example #2 (Ironsides 'luckygen1001'):

1. Commercial production foundry setup: Potentially Yes
2. Number of successful iron melts exceeds 200: Yes
3. Makes and sells (or has at some point) iron castings: Potentially Yes
4. Type of fuel: Waste Oil
5. Type of burner: Drip-style oil burner


Example #3 (porositymaster):

1. Commercial production foundry setup: Yes (operates his own for-profit commercial foundry)
2. Number of successful iron melts exceeds 200: Yes
3. Makes and sells iron castings: Yes
4. Type of fuel: Diesel
5. Type of burner: External-combustion Ursutz-variation (constructed from stainless steel pipe)


So here we have three guys who use three totally different burner types, and all have excellent and consistent success with cast iron melts and castings.

So what is the conclusion to be drawn about what is the best burner type to be used for melting iron?
Again, it boils down to what works for you, what you prefer, and how well that applies to your exact application.

 

The drawbacks of the Ursutz-style burner are as follows (per porositymaster):

1. The burner has sufficient output to damage a clay graphite crucible even without direct flame impingement.
Using an Ursutz burner to lower melt times can be counterproductive if you only get 5 melts per crucible before the crucible fails.

2. The Ursutz burner may not be easily scalable to larger sizes (the jury is still out on this statement, but it seems to be true per porositymaster).

3. The burner chamber really needs to be constructed from heavy wall stainless steel in order to have any durability. Mild steel Ursutz burners don't last very long, and even a stainless steel Ursutz burner can have problems melting off its output tube. I don't know of anyone who operates a refractory-style Ursutz burner, and so that style may alleviate some of this type of problem.

4. The Ursutz burner radiates a tremendous amount of heat, which makes for a very hot melt when standing next to the furnace. I think if a meltal Ursutz burner where insulated, it would just melt.
A refractory-style Ursutz burner could be insulated.

5. An Ursutz burner is a rather heavy and bulky affair when compared to either a siphon-nozzle or drip-style burner.

6. An Ursutz burner is not what I consider a "plug-and-play" like a siphon-nozzle burner, and I was never able to get the Ursutz burner I constructed to work correctly, must less melt iron.
But if built correctly (that is a big if; it took porositymaster long time to come up with a working configuration/dimensions), the Ursutz burner is a highly efficient and extremely high output burner (as mentioned above sometimes too high output of a burner, but porositymaster says he has reduced the fuel flow for his burner to increase crucible life, with a resulting longe but still acceptable melt time).

The reason that a Ursutz burner can work so well is that it can deliver a fully or almost fully combusted stream of exhaust gasses into the furnace, which means that the bottom of your furnace is receiving very hot combustion gasses, and the fuel and oil do not have to swirl and mix with air in the bottom of the furnace, and then begin to combust fully at some point higher in the furnace.

 

So how am I going to figure out how to correctly adjust my 2.5" diameter Delavan siphon-nozzle burner?

As shown in my latest "lower-mass" furnace build (lowest-mass furnace being defined by me as the type ironsides uses, which is ceramic blanket insulated coated with a zircon high-temperature coating), I am going to use temperature probes installed on the exterior of the refractory shell at some strategic points, so I can indirectly measure furnace temperature for any given burner/fuel flow/compressed air/combustion air setting.

My furnace build link is listed below each post.

Without some type of measurement, you are just making blind guesses about whether your burner settings/fuel usage/melt times are optimized, and whether you are producing the hottest temperature inside the furnace.

Some have suggested I think oxygen sensors in the waste stream, but I thing (prove me wrong) that simple thermocouple temperature measurements of the outside of the refractory shell is a much simpler and reliable method.

I like using a siphon nozzle burner for all the reasons I mentioned above, and there can be no doubt that a siphon-nozzle Delavan burner can work well in a commercial iron foundry setting give what scavenger has demonstrated.

I do have some situations where I could be away from home at shows/festivals, and will not have access to more than a small pancake air compressor, so my next test (as mentioned previously) will be to try and operate the Delavan siphon-nozzle burner without compressed air (once the furnace gets hot), in the same fashion that ironsides uses with his drip-style burner, ie: deliver the oil to the end of the furnace tube and let the hot furnace to the work of vaporizing the fuel.

When am I going to do this test? (edit: I did the test and figured it all out).
That is a good question, and not necessarily one I can answer, although I am caught up a bit more with work, so don't have many good excuses for not finishing my new iron-specific furnace, other than perhaps it can be 100F in the shade with 90% humidity around here this time of year, but having lived here forever that is just a matter of routine and drinking a lot of water.

 

There are some (many?) here who build their own version of a siphon-nozzle burner, but I have heard from at least one member that a burner using a Delavan (or equivalent Hago) siphon nozzle makes for a much more consistent and controllable burner than the home-built variety.
That being said, there are those here who use their home-build siphon nozzle burners with great success.

My thoughts on building your own siphon nozzle burner (I built one from a cutting torch tip, and it worked well but used excessive compressed air):
1. I would rather focus my efforts on the end product (making accurate and easily machinable small engine parts), and also on pattern making, rather than making burner parts.
2. I do like to make pretty much everything myself, but I find there is little to be gained by machining my own siphon nozzle parts when I can purchase a high-quality product reasonably online.
3. Using a Delavan nozzle gives you a well defined, well proven, and usable starting point for an oil burner.

There have previously been more than a few complaints about how difficult a siphon-nozzle burner is to set up and operate.
All I can say is look at scavenger's videos, pay attention to those who have a lot of success with siphon-nozzles, and pay attention to the details of building and setting up a siphon-nozzle burner.

A siphon-nozzle burner is definitely not for everyone, but for the naysayers of siphon-nozzles, I respectfully say that I find them easy to setup and use if you have the desire to learn how to do it properly.

 

For comparison, here are videos of the three types of oil burners that I review above, all of which work very well:

Ironsides drip-style oil burner:


This video has a lot of useful information such as furnace dimensions, crucible and plinth dimensions, drip-oil burner configuration, etc.
The furnace is ceramic blanket construction with a high-temperature zircon coating, and is the lowest mass iron furnace I have seen, which equates to excellent melt times and minimal fuel usage.

 

This is scavenger's furnace/burner setup:

This is a high-mass cast-refractory furnace, using a Delavan siphon-nozzle burner.
This burner demonstrates that a high-mass furnace can be very successfully used to melt large quantities of iron (I think he is using at least a #70 crucible).
I believe the interior furnace dimensions are similar to ironsides furnace, perhaps slightly taller?


This video gives a pretty good demonstration of how to light a siphon-nozzle burner, although I consider my setup much easier since I calibrate my needle valve (for fuel flow) ahead of time with the furnace off, and then generally do not change the needle valve setting again (I lock the needle valve by tightening the gland nut), but instead make final adjustments by slightly modifying the combustion air damper. I use a ball valve ahead of the needle valve, and just open the valve and compressed air ball valve fully to start my burner.
My arrangement avoids the round-robin type approach that scavenger uses, ie: adjust compressed air, fuel, combustion air, repeat several times.
My arrangement also avoids most of the smoke that scavenger generates when in the process of tuning his burner, and also gives a consistent setting for every melt, not a randomly adjusted burner.

Scavenger does have the burner adjustment thing down to a science, but there is a better way in my opinion. There is no arguing with scavenger's succes, especially compared with my lack of success, but I think my points are still valid and would simplify greatly his burner starting.

 

This is porositymaster's current furnace and burner arrangement:
He is also experimenting with several other burner/furnace configurations, but this is the one he has over 200 successful iron melts with, and the one he operates a commercial (for hire) foundry with at this point in time.



It took him a long time to design and debug this burner, and I would not recommend this type to a beginner, and perhaps not recommend it to even an experienced person due to some of its drawbacks.
He uses a Toro leaf blower for combustion air, and runs it on the lowest setting.
The burner and furnace is all stainless steel construction.