Rubens Tube

A Rubens Tube

The Rubens Tube is a fascinating physics demonstration tool.  It was first developed by Heinrich Rubens back in 1904.  But, I’m not going to insult your intelligence and repeat what wikipedia has to say.  You can check that out yourself.

I love the device because it is such a crowd-pleaser.  I like to set up my tube at a party or Mindshare event and watch people’s reaction to it.  It couples music and fire, two very primitive and ingrained human infatuations.  It’s hard to resist, really.  People will naturally stare at the fire, but only after a few beats do they realize that it’s dancing to the music.  Suddenly they’re asking questions and wish to know more.  If you ever see me around my tube at a party, you’ll notice I spend a lot of time describing how it works to those around me.  I don’t intend to lecture, but they keep asking the questions.  I certainly don’t mind.

The physics of a Rubens tube is quite simple really.  When tones are played through the speaker on the end, the gas resonates in the tube, much like it would in a musical instrument.   A standing wave of pressure gets set up inside the tube.  The sections of the tube with higher pressure will have higher flames.  The opposite is true for the areas with lower pressure.  This creates a sine-wave of fire along the length of the tube.  The tube can resonate with multiple frequencies at the same time, but they’re all harmonics of the base resonant frequency of the tube.  It is not acting as a graphic equalizer, with low frequencies on one end and high on the other.  Many people make that mistake, though.

At the moment I’ve got a few Rubens tubes that I like to bring to parties.  I’m currently building a new one for a much larger permanent installation in my backyard.  I’ve also got plans for a few more interesting tubes in the works.  Eventually…

I’ve got a short series of How-To Posts so people can build their own Rubens Tube at home.  Be very respectful of fire, and use your common sense.  These things are about as dangerous as a barbeque grill, but they’re not very safe either.

Here are a couple of youtube videos I made a few years back of my most reliable 8′ 8″ aluminum Rubens tube. Enjoy!

 

 

16 responses to “Rubens Tube”

  1. John

    I have lots of questions concerning the Rubens tube concept. I build car audio systems and I’ve become fascinated with the 2d Rubens box or pyro board. I want to put one In the back of a small truck. I haven’t seen one in the scale that I want on the internet yet. My main concern is safety. And I just don’t know where to start. I don’t know what size speaker will have the best results for the area that want or if I would need more than one or a bunch of smaller ones. Would it be best for a bunch of smaller separate boxes together or one big thin tank. I’m sure there is more obstacles I haven’t thought of yet. Since you have experience building one and I don’t,I thought i’d hear your thoughts on the idea

  2. John

    I plan on making one 2 by 4 feet first so I can experiment on a rectangle shape box because a truck bed resembles it. I’ll keep you posted. Thank you for the help. I’ll probably ask questions periodically. But now I know where to get started.

  3. Michael McDowell

    Hi guys
    I am in the process of getting material together to make a 2D Ruben’s board/box.

    First off, let me just say that I’m trying to make something that will look cool in a patio setting with music playing. Basically I’m looking for flames bumping to the beat. Creating nodes/anitnodes isn’t really what I’m going for.

    The one Rubens table (the only one that seems to exist) that I’ve seen was square and had two speakers at a 90 degree angle. Do you guys think it matters if I have one or two speakers?

    Also I’m trying to figure out how to not have the speaker housing melt while it’s lit up. Steel looks like the best choice of metal to keep the housing cool, but you expressed concerns with resonance. Do you think it matters while I’m playing music if it’s resonant or not?

    Also, square vs rectangular construction: does it really matter?

    I’m planning on using 4 inch speakers mounted on the sides without a membrane between the speaker heads and the gas. The whole box should be 24″ x 24″ or 36×36 depending on material availability.

    John, if you’re integrating it into an audio system, could you have other speakers playing the same stuff outside the box so people can hear the music so the size of the speaker inside of the box doesn’t really matter?

    I just wanted to get your thoughts first!

  4. Bia

    I have made a 5ft long Rubens tube. I am working on its waves. Can you tell me uptil what no of harmonics the flames visualise standing waves?

  5. Eugene McDonald

    I am considering building a curved Ruben’s tube, possibly out of an old French Horn. Is there any reason this won’t work?

  6. Peter B

    Is it possible to run this as part of a live rock show? Like somehow hook an organ up to it…kill the lights and only have it burning and changing along with the organ? Or does it only work with pure tones?

  7. Mukundhan

    Can we use LPG instead of propane gas? Will there be any issue?

  8. Lindsey

    Do the tube/holes have to be parallel to the floor? Or would a curved tube work as well? I’m thinking about designing and forming the tubes into various shapes. Also, do you think theres a way to coat the pipe in a heat safe material to avoid burns if touched? Thanks!

  9. Jessica

    Hello,
    I would like to build a Ruben’s tube to use as a demonstration for a science show. My main concern is about safety – how hot does it get after using it for a few minutes? How long do we need to wait until it cools down and we can handle it by hand ?
    In your opinion, what are the major safety issues with Ruben’s tubes?
    Cheers
    Jessica

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