Oil burner build.

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

100model

Well-Known Member
Joined
Nov 7, 2012
Messages
206
Reaction score
191
Location
Victoria Australia
I came across this video of an Aussie Machinist/metal caster which shows him building an oil burner, he is up to part 4 and in this video he lights up the oil burner for the first time on camera. This is where inexperience can make lighting an oil burner so difficult. Have a look at the 30:00 minute mark, you will have a bit of a chuckle when the oil burner goes out. As he uses it more this should not happen. There is big one safety issue with his set up, using a plastic diesel tank so close to the furnace. It should be steel instead of plastic and it should be at least 3-4 meters from the furnace because the heat that comes from the furnace when opened can easily melt plastic. If you want to build an oil burner watch all the videos from part 1 and gives detailed instructions on how to build it.
 
There is a lot of variety in the oil burner information that you can find online, and everyone has their favorite oil burner design, and specific oil burner type, ie: siphon nozzle, pressure nozzle, drip-style, Ursutz, etc.

I studied and experimented with oil burners for years, and while there is a lot of information about them online, much of it is misleading, or incorrect, or incorrect for a burner used in a foundry situation.
I post these thoughts with the hope that this will provide clarity to those who are interested in building their own oil burner.

Generally speaking, if you see online information about oil burners, verify that information, because you may find out like I did that much of it is incorrect.
Many folks will literally post any information, regardless of its accuracy, in order to drive view count and subscriptions.

A few observations:

1. If the burner tube is built in a "Y" configuration, the fuel and/or compressed air (and sometimes propane) pipes can come straight out the back of the burner, which is infinitely easier to build in my opinion than the offset tube arrangement.

2. In his Part 1 oil burner video, he makes a number of statements that are not true.

a. Diesel oil burners are more difficult to light and manage while burning (not true at all if you are using diesel. Perhaps more difficult to light if you are using using waste oil. I literally NEVER adjust my burner, ever. A correctly setup oil burner does not require adjustment once it has been calibrated and set up).
b. The diesel must be atomized into a fine spray. (not true, 100model uses a drip-style oil burner without a fine spray, and it works well, but needs propane to start. The fine spray eliminates the need to start with propane when using diesel, and so that may be desired, but is definitely not necessary with an oil burner.)
c. Requires a blower for optimal flame state. (not true, I have used my siphon nozzle burner in a naturally aspirating mode, with no blower, and it works well with aluminum. A blower is needed if you are going to melt iron.)
d. Can emit smoke and soot. (true only if you don't know how to adjust and operate an oil burner correctly. You should never see smoke or soot when operating an oil burner with diesel).
e. Spills and leaks can be messy. (this may be true if you have spills and leaks. You should not have spills and leaks generally speaking.)
f. No compressed air. (His burner is a pressure-nozzle type, and it does not require an air compressor, which is a plus in my opinion, but more on this later).

Some other observations:

1. The spin vane that he uses at the end of the burner tube is not required for an oil burner, and I think you get better combusion air flow without the spin vane.

2. The way he slowly speeds up the fuel pump and combustion air blower slowly is one reason he is getting the smoke and soot.

3. He has a significant amount of soot buildup on the furnace wall and on the side of the crucible.
This is not normal, and indicates that his burner is not operating correctly.

What is happening with his burner:

1. It appears that his fuel pressure is too low, and so he is not getting enough atomization to get complete combustion of the fuel.
It looks like he is getting fuel puddling in the bottom of the furnace, which is a sign of incomplete atomization.

2. The furnace is smoking after he turns off the burner, which is not normal, and also indicates that he has fuel puddling inside the furnace.

.
 
Last edited:
Here is my siphon-nozzle style diesel oil burner.
As you can see in the first video, no smoke at all, with a perfectly clean burner.
Note that it is extraordinarily hot looking into the top of an oil burning furnace, and it will melt a face shield or camera in seconds.

The valve tree that is visible near the leaf blower in the first video was a test setup, and it is not normally used with the burner.

In the second video, I had rainwater get into some of the insulation around the furnace, and so what looks like smoke is really steam.
But notice that there is very minimal smoke or soot during startup or running (assuming you don't use too large a piece of cardboard under the crucible like I did, which caused the flame-out).

I have the nozzle calibrated for 2.6 gal/hr, and so it is just a matter of turning the compressed air and fuel ball valves on at the same time (needle valve maintains the fixted 2.6 gal/hr rate, and once it is calibrated, it is never adjusted again), and then turning on the combustion air blower and ramping up the air to maximum with a dump valve (sometimes full combustion air all at once will blow out the flame).

The flame-out that you seen in the first startup attempt was due to using two layers of carboard under the plinth, that were square pieces of cardboard, and they protruded out from under the crucible, and interfered with the startup flame.

1:48 in the second video is what the furnace looks like when the lid is opened, with no soot or smoke.

An open furnace produces an extraordinary amount of radiant heat, and you need a lot of leathers for protection, and shaded lenses, when you open a hot furnace.





 
Last edited:
I agree with 100model, that fuel tank is too close to the furnace.
That could cause a serious fuel spill.

What does Mr. Presling need to do to solve his smoke and soot problem?

My guess is that he needs to use a fuel oil gear pump (with a good filter ahead of it), to get more pressure to his pressure nozzle.

I think more pressure would stop the fuel puddling, and stop the smoke and sooting.

I have experimented with verying the compressed air pressure on a pressure nozzle burner, which is doing the same thing as varying the fuel pressure on a pressure nozzle burner, and confirmed at at some point, the fuel droplets are too large, and you begin to puddle fuel in the bottom of the furnace.

I have been told that puddling fuel in the bottom of a hot furnace is impossible, but I can assure you it is very possible (been there, done that).

So it begs the question, how does 100model use a drip style oil burner, with very low or no fuel atomization, and yet no fuel puddling in the furnace?
This is a mystery to me, and not something I have been able to duplicate.
We need to go over to 100model's house and find out what he is doing, but it would be a long swim, and a croc would probably get you.

Edit:

Another cause of fuel puddling in the furnace is due to having the nozzle tip too far back in the burner tube.
This causes severe fuel puddling.
The tip of the nozzle (pressure or siphon type) should be almost at the end of the burner tube; perhaps 3/4" away from the end of the burner tube.

.
 
Last edited:
Here is another pressure nozzle style oil burner, which uses a fuel pump like the one in the video in the first post.

The fuel pump seems to be a very inexpensive option for pressurizing fuel.
I am not sure about longevity of a small fuel pump, but it is a popular method.

One thing to remember is that an oil burner is not really designed to operate well outside the furnace, and many people assume that since an oil burner does not easily maintain a flame ouside the furnace, then it will not maintain a flame inside of a furnace, which is not true.

This fellow changed to an oil burner for the same reason I did; ie: he got tired of getting low vapor pressure out of a propane tank when it became cool and started icing on the exterior.

I have operated my oil burner on diesel at 30 F, and with no termperature problems at all, and with no fuel preheat required for starting or operation of the burner.

It remains to be seen if this guy has the same fuel puddling problems as the first video due to low pressure.
This will be a good comparision.


 
but it would be a long swim, and a croc would probably get you.
No crocs where I live but we have sooo many sharks.
So it begs the question, how does 100model use a drip style oil burner, with very low or no fuel atomization, and yet no fuel puddling in the furnace?
This is a mystery to me, and not something I have been able to duplicate.
I used to have fuel puddling the bottom of my furnace until I solved the problem, leaky fuel control valve that would not stop oil flowing completely after furnace shut down. I think that is part of the problem with his furnace but also he needs to refine his technique on using the blower and amount of fuel to stop sooting up his furnace. Soot in his furnace means diesel is not burning properly.
he got tired of getting low vapor pressure out of a propane tank when it became cool and started icing on the exterior.
If you listen carefully, he complained on how slow his furnace was when melting aluminuim and brass. If he had of used a simple propane burner like mine with a blower it would take fraction of the time using a naturally asperated burner. To give you an example my propane burner can melt twice the amount shown in his video and it takes only six minutes from cold. I have done countless experiments comparing waste oil and propane burned using the same blower and weights in aluminuim, bronze and cast iron and in all metals my furnace uses 1.5% more propane than waste oil with the same melting times.
Generally speaking, if you see online information about oil burners, verify that information, because you may find out like I did that much of it is incorrect.
He copied the design from someone else online and that person copied it from someone else and you get the picture a lot is lost in the translation. Also every one has their own ideas on how to build things so some things are changed to suit your own taste. It a good design but could use some mods to improve it.
Another cause of fuel puddling in the furnace is due to having the nozzle tip too far back in the burner tube.
Too true, the spray can condense on the burner tube and then run in the furnace without burning.
 
The guy in post #5 is different than the guy in post #1, and the guy in post #5 does show an iced up propane bottle.

But you are correct, a popane or natural gas burner that is set up correctly will melt aluminum quickly, and will melt iron too, as shown by others (not me).

.
 
My diesel burner uses a gear pump to pressurise a conventional Delavan nozzle and it does suffer from some pooling when switched off.
This is inevitable in my case as switching off the pump means a slow decrease of pressure in the fuel line to the fine nozzle until it literally squirts a stream of unatomised diesel into the hot furnace. I admit that a shut off valve closer to the nozzle would reduce this.
One thing I noted was that his furnace is constructed with hard refractory, as I did originally, and these suck so much heat up before you can do a melt.
My latest furnace is ceramic fibre lined, as per 100Model I believe, and the difference is incredible.
My earlier furnace took 30-40 minutes to do a A3 crucible melt and this is now down to 10 mins in the ceramic blanket insulated type.
This using Propane I add. I have to test the diesel burner more thoroughly yet.
Just my two pennies :)
 
For those who may build a ceramic blanket furnace, it is highly recommended to coat the ceramic blanket furnace interior with something like Satanite, in order to keep the ceramic fibers from getting blown into the air, where they can be inhaled.

My first furnace had 3" thick walls of dense refractory, and it took 30 minutes just to heat up the refractory, before any melting occurred.

My second furnace uses a 1" thick hot face, backed up with insulating fire brick, and then two layers of 1" ceramic blanket around that.
My second furnace is a good tradeoff between durability and heat-up time.

Iron melts and iron slag splatter tend to be tough on furnace refractory, and the 1" Mizzou hot face withstands iron slag very well over long periods of time. And while Mizzou may crack, it does not crumble under iron temperatures, and the cracks can easily be patched.

The dense hot face patching material is called "plastic refractory", which is a material that is rated for 3,800 F (the brand I use), and does not require adding water, since it is in a putty-like form.

The ceramic furnaces are very popular these days, and are definitely here to stay.
And they heat up very quickly too, and save time and fuel.
And a ceramic blanket furnace is infinitely lighter than a dense refractory furnace, and so easy to move around and/or transport.

The ceramic blanket coating can be damaged if you contact it with the lifting tongs, but it can be recoated.

Edit:
As I recall, ceramic blanket can be purchased in different temperature ratings, but the price goes up exponentially with the temperature rating.
The same is true with insulating fire bricks. A 3,000 F insulating fire brick is shockingly expensive, and thus the reason I use the 2,500 F bricks, which are a fraction of the cost of a 3,000 F brick, and then a 1" Mizzou hot face to protect the 2,500 F insulating fire bricks.

Mizzou is relatively inexpensive, as is plastic refractory.

2,500 F ceramic blanket and Satanite are also relatively inexpensive and readily available.

.
 
Last edited:
The guy in post #5 is different than the guy in post #1, and the guy in post #5 does show an iced up propane bottle.
Sorry I should have watched your posted video first before commenting. The iced up propane bottle can be easily fixed by using a larger plastic bucket and filling up with hot water. It only ices up when smaller bottles are less than half full. The only reason why I started using waste oil is because it is far cheaper than propane.
My earlier furnace took 30-40 minutes to do a A3 crucible melt and this is now down to 10 mins in the ceramic blanket insulated type.
This using Propane I add.
This is why I would never go back to using castable refractories, it just takes too long for cast iron.
 
Hi Green twin.
Your comment earlier: "One thing to remember is that an oil burner is not really designed to operate well outside the furnace, and many people assume that since an oil burner does not easily maintain a flame outside the furnace, then it will not maintain a flame inside of a furnace, which is not true."
VERY TRUE!
I make burners for inside combustion chambers (firebox) of boilers.
These are always re-tuned after initial manufacture to suit the back-pressure from the "firebox and flue". Not just a case of designing an appropriate cross-sectional area, but the temperature and external air supply are TOTALLY different between "outside air" and "Inside the combustion space".
Fuel and air (for combustion) must be mixed completely before the fuel-air mixture burns correctly as well. - Something the guy in your attached video doesn't seem to appreciate.
Sometimes, "randomly" designed gas burner will have the right amount of air, and it mixes well with the fuel and the burner works. Usually because someone has cleverly copied a working burner!
But more often than not things are not OK, especially when an "external burner" is fed into a closed firebox!
I spent a few years learning the lessons before I got a good understanding of what is needed.
So I'll be watching and learning about your furnace oil burners with interest.
Thanks,
K2
 
I started experimenting with burners in 2011, and the first thing I tried was a commercially made naturally-aspirated (no combustion air blower) large propane burner.

At the time, I had zero foundry experience, and so I had all sorts of problems getting the propane burner to work correctly.
I had no concept of adjusting the fuel/air mixture, or the dynamics of a propane burner.

Propane burners generally require a flare on the end of the burner tube to burn correctly outside of a furnace (but not when used with a furnace typically). A naturally aspirated propane burner can be adjusted to burn lean, neutral, or rich.
All these things I had to learn by trial and error, with much consternation when I could not get the burner to operate correctly due to my own ignorance.

There is a lot of literature about how to operate a propane burner, but typically it applies to forge work, and foundry furnaces do not operate the same with a propane burner. Getting a furnace burner too lean can cause a lot of slag formation, and can be hard on the crucible and furnace lining too.
I run my diesel burner on the slightly rich side.

My first attempt at trying to burn oil was with a $20.00 paint sprayer from Harbor Freight, and a can of kerosene.
I would spray kerosene across a lit torch, and what a spectacular ball of fire that was.
The wife knew I was up to no good right from the very beginning when she saw fireballs going past the kitchen window.

Then I discovered a Delavan siphon spray nozzle burner design, and that became my burner type, used with diesel.

As Steamchick mentions, siphon and pressure nozzle burners used for heating units discharge into a combustion chamber, and you select a nozzle that gives the fuel flow rate and spray angle that you need to make the burner work with the shape of the combustion chamber that you are using.
You can go so far as to get hollow cone and solid cone pressure nozzles too, also to provide better burn control, depending on the type of combustion chamber configuration, such as wide and shallow, or long and narrow.

The idea with an oil burner is to burn the atomized fuel as completely as possible INSIDE the furnace.
Most burner videos you see show a burner mounted on a workbench, and they discharge an impressive flame.
Making an impressive flame on a workbench and tuning an oil burner to get complete combustion inside of a foundry furnace at iron melting temperatures can be very different.

Basically you start with about 2.6 gal/hr of diesel as a flow rate, and then dial in the amount of combustion air that completely burns that fuel flow rate. I use a variable speed Toro leaf blower, with it running on the slowest speed setting.

I start my siphon nozzle using compressed air and diesel only, and it will run pretty well in this configuration as a naturally aspirating burner, but to get to iron temperatures, the combustion air blower is then turned on, and this is when an oil burner started to produce some serious heat.

It is wise to always start any type of burner with your furnace lid open, and only close the lid when your burner is operating in a stable fashion.
One guy mentioned that he launched the lid of his furnace over the top of his house. Don't do this.

At 2.6 gal/hr, an oil burner produces about 110 KW.
For my size furnace, using a higher or lower fuel flow rate actually makes the furnace run cooler.
There is a certain spot where you can combust X amount of fuel using Y amount of air, for a furnace interior surface area of Z, and this is the hottest flame you will get with a given furnace.

If an excess of 2.6 gal/hr is used with my furnace, the excess fuel can not combust inside the furnace, and the result is a large flame outside of the furnace, which is where the excess fuel finally has enough oxygen to burn.

As I mentioned, I run my burner slightly rich (reducing flame), with about 4 inches of yellow flames out the lid opening, to minimize slag formation.
An oxidizing flame produces a lot of slag, and I avoid oxidizing flames.

.
 
Last edited:
When I first started to immerse a propane bottle in water I used room temperature water so it was OK in warmer weather but in winter it was another story. What happened was a thick layer of ice formed on the outside of the propane bottle when under water. It was a great fridge but the liquid propane was very slow to turn into gas. Hot water was the only solution or run a hose from a hot water tap to warm the propane bottle.
 
On my model boat, using 90gm. Butane disposable cartridges, the temperature drops, burner output drops so the boat won't run and simply drifts.... so I made a simple stand from the bottom plate of a spare used canister, and a flat plate, and with an inlet and outlet pipe connected it in-line with the condensate return to the water-feed tank. There is just enough warmth from the condensate to keep the gas pressure OK. One guy with a butane powered model engine, with similar reservoir cooling issues, liked my tank heater, so was considering making one using his engine cooling water from his radiator return to heat the butane tank. I don't know if he ever did though. I guess a 500W electric fan heater of electric hair dryer may be adequate on a large propane tank firing a furnace?
K2
 
I guess a 500W electric fan heater of electric hair dryer may be adequate on a large propane tank firing a furnace?

Or do like many backyard foundry folks do, which is kick the propane tank and burner to the curb, and use diesel or waste oil with an oil burner of some type (at least for iron melts).

An oil burner solves so many problems.
If you design it that way, you can refill your fuel tank while the burner is running (I don't do this, but it is possible with oil).

And no more having to return propane bottles for exchange, which is not that simple around here.
Almost every gas station sells diesel 24/7/365.

.
 
I too like the idea that "road fuel" - even with all the Road use taxation - is often cheaper than "shop-bought" fuel like LPG, Paraffin, Coleman fuel etc. so engines and burners designed appropriately for those cheaper fuels pay for themselves very quickly. And when camping (in the 1970s) travelling by Motorcycle, there was always an adequate supply of fuel for the petrol stove - whereas my mate always ran out of gas when there were no shops around! In 1 week on the Isle-of-Man (TT week) I did all the water boiling and major cooking for just a couple of pints of petrol, whereas he used lots of cans of gas to do less cooking - cost more than a gallon of Petrol!
K2
 
You can go so far as to get hollow cone and solid cone pressure nozzles too, also to provide better burn control, depending on the type of combustion chamber configuration, such as wide and shallow, or long and narrow.
GreenTwin or others, can you comment on how to choose among the many options that Delavan provides? I understand the flow rate and the angle, but the hollow cone or solid cone or so on ... what is better for a foundry? For that matter, is there a better angle to use?
 
but the hollow cone or solid cone or so on ... what is better for a foundry? For that matter, is there a better angle to use?
As long as the fuel burns it would not matter. With my furnace it will melt cast iron and I have never worried about those issues.
 
I did all the water boiling and major cooking for just a couple of pints of petrol, whereas he used lots of cans of gas to do less cooking - cost more than a gallon of Petrol!
Years ago I tried an experiment using petrol instead of diesel to make the waste oil flow better and what I found was petrol made the furnace take longer to melt cast iron. I tried it a few times to see if it was a one off, nope diesel was better to add to waste oil than petrol.
 
As 100model mentions, you can use a drip-style oil burner, and you don't need a siphon or pressure nozzle at all.

I built a drip-style burner just like 100model's burner, and after many attempts to make it work correctly, I could never get good control over it, and it caused fuel puddling in the bottom of my furnace.
I tried for a long time to make my drip-style burner work, but I gave up eventually.
I cannot get a drip-style burner to work correctly with my furnace, and I know a lot about oil burners.

So why do some folks use pressure or siphon nozzles when a drip-style burner will work?

1. A drip-style burner requires a propane start, and a siphon or pressure nozzle burner running on diesel does not.

2. A siphon or pressure nozzle burner are very controlable, and have a wide turn-down ratio, ie: they will operate over at least a 4:1 fuel ratio.
A nozzle rated for 1 gal/hr will also operate well at 4 gal/hr while still achieving good atomization.
I am aware of one individual who uses an Arduino controller, with a thermocouple and control loop, to control the output of two siphon-nozzle burners for his aluminum scrapping furnace. This arrangement gives him automatic and precise temperature control of his melt.
You can't do this with drip-style burners.

3. My siphon nozzle burner is extremely stable in operation.
I use 10 psi pressure on the fuel tank (with a 30 psi safety relief valve), and this gives rock solid operation.
I literally never adjust my burner; not during a melt, and not between melts.
There is much to be said for never having to adjust a burner.

4. I have started my siphon nozzle burner on diesel down to 30F, and it starts and operates instantly, with no propane warmup required, and no preheating of the fuel (the diesel tank and the diesel in it are at 30F).
A siphon and I think a pressure nozzle burner running on diesel are impervious to a wide range of outdoor air temperatures.

There is a white paper out there that was written by Delevan's lead engineer, and he goes into great detail about the various types of oil burners; how they work; and how they differ.

I will start a post and see if I can clarify a bit more.

Edit:
Siphon and pressure nozzle thread started here:
https://www.homemodelenginemachinis...-style-foundry-oil-burners.35340/#post-398982
.
 
Last edited:
Back
Top