Mini Modular Gas Air Intake for D.I.Y. Furnaces and Blowtorches

FIRST OFF, thank you for checking out this model, I put a lot of time and sanity into it and I hope that it works with your needs! If you could like and download the model even if you aren't sure you need it, I would be very thankful, and if you made it please leave a make with your thoughts and criticism, I'm always trying to make better models for the people that need them and any criticism or feedback would be greatly welcome.

I wanted to make an air intake for my brand new DIY metal smelter. It's made out of multiple small pieces that allow for easy part replacement for fine tuning and in case of failure, It requires a V6 3D Printer nozzle in the beginning and has multiple threaded parts to allow for easy optimization for your personal needs and fuels.

HOW THIS WORKS:

This model is an inspirator for making your own torches for your furnace or for the workshop. It uses a principle of air dynamics called the venturi effect. This effect states that when a stream of gas is pushed through a constriction, the pressure of the gas decreases while the velocity increases. We can utilize this to create static, powerless, gas mixers. Once the pressurized fuel leaves the small exit from the V6 nozzle, the pressure is so low that the surrounding atmosphere gets sucked in with it to try and equalize the pressure between the two, leaving you with a mix of fuel and air which allows the fire to burn very hot and stable.

The tolerances are 0.2MM for the threads, and 0.3MM for the V6 nozzle Threads.

I HIGHLY recommend printing at a low speed to prevent any possible defects that will lower the efficiency of the parts.

Supports are required on most parts, not too many though. Find out where they should go, you're a smart cookie.

The pipe threads there are right now are 1/4" for the intake and 3/8" for the output, the intake for the fuel should fit most barbed fittings; also quick connects, but those are leaky at these pressures. The outlet fit the pipe that I had so I just made that size, if you want a different size ask me in the comments!

The usual configuration of these parts are:

1. Gas Intake, V6 Nozzle Part
2. Air Holes
3. Spiral “Mixer”
4. Pipe Adapter

SETTINGS FOR PRINTING-------------

• Speed - Low
• Layer Height - about 30% of your extrusion width, Detail is key for this model.
• Supports - Required
• Infill - 50% or higher for that high strength
• Annealing - Recommended but not required (annealing adds strength and heat resistance but may goof up thread clearances.)
• Brim - Recommended, but not required.
• Material - Poly-carbonate is the best for its thermal resistance and dimensional accuracy, but choose the highest temp material you have and can print quality parts out of, PETG works fine, PLA should be avoided for its low melting point.

FINE TUNING YOUR FLAME----------

This model has multiple parts and files so that you can experiment with what works best, I found that this was the easiest way to configure it without making it too complicated.

What works for me is a 0.4MM nozzle with the 5MM air intake part and the short spiral followed by the end. This configuration may not work for you, but its a good starting point.

If the flame wont ignite and seems to extinguish the moment you take of an external flame, its being choked out and has way too much air in it. Try the smaller holed variations of the air intake, and if that doesn't work, put in a nozzle that has a bigger hole. Beware though, this will lower the overall efficiency of the intake due to the lower velocity of the fuel and therefore less venturi action.

If your flame isn't quite strong enough or there's any orange in it, You aren't getting enough air in that mixture. Try a smaller nozzle diameter, this will allow more air to mix in by increasing the escaping velocity of the fuel. If that doesn't work, try using a wider air intake part. If none of that works make sure you have the spiral bit, that mixes the air and fuel, allowing it to stay alight even without any direct exposure to the outside. You may also be covering one or more of the intake holes, and that will ruin your fire.

If your flame isn't at the end of the tube or inside an ignition chamber, your mixture may be a bit off or your fuel-air cocktail is speeding out of the exit way too fast to be stable, try lowering the pressure of your fuel by turning down the valve your tank has.

A good way to test if your air intakes are working properly is to take a small lighter and hold it right next to the intakes, the flame should get sucked right in if it works properly, but be careful as if it isn't working, it may ignite instead.

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WARNINGS:

I claim no responsibility for any damage that this model does to you or your furnace, by using this model you should know what you're getting into and know how to be safe while using it.

Fire is very dangerous so be sure to use any controlled fires outside or somewhere with plenty of ventilation, like a garage with the doors open.

Propane flames can reach up to 3500*F - 1900*C, so exercise caution when handling anything involved with the flame, and wear thermally protective gloves. Always use metal tools to grip and forge any hot metal.

Galvanized steel contains zinc, which produces toxic vapors when significantly heated up, and can degrade over time from nasty oxides and chemical reactions with the air. If your are using galvanized steel for anything that will get red hot, be careful to not inhale any of the oxide residue or vapors it produces.

BE SURE TO MAKE THE FIRST PART AIRTIGHT!!

Use Teflon tape and be sure to wrench it in there about a centimeter and a bit, or until you feel a significant resistance. If this part leaks fuel, it will most likely catch fire and melt, and that's not what we want to happen. All the other parts do not have to be airtight, except for the nozzle threads. If the nozzle leaks, heat up the nozzle with a lighter or torch just a tiny bit, and then screw it in, this insures that the plastic and the nozzle are welded together, but changing nozzles may be an issue for the future.

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Very useful pages that helped me model this and understand the fluid/air dynamics in play:

https://www.foxvalve.com/air-gas-steam-vacuum-ejectors/introduction-to-air-steam-and-gas-ejectors 

https://en.wikipedia.org/wiki/Venturi_effect 

https://en.wikipedia.org/wiki/Inspirator