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Hi All,
We have the larger version Jonah refers to and I am in the process of
trying to make it as safe as possible. My concern is that Propane is
very hazardous. Larger cylinders like those used in BBQ grills are not
allowed by most fire codes to be inside habited buildings for extremely
sound reasons. Thus whatever you do, use the smallest cylinder you can
find. Use a regulator as well.
The tricky part is the tube itself. In our case it is about 3 inches in
diameter and five feet long. It has very small holes drilled in a line
at the top which presumably will work as a "flame holder" and thus
prevent flashback. However, I'm just the littlest bit edgy that under
certain circumstances the holes could act like a cannon's touch hole.
This could happen if there is just the right mixture of air and propane
in the tube, for example just after you turn the gas on and before the
tube has been purged out. This could lead to a most unpleasant
explosion. My thought is that this would vent out the end with the
membrane and thus be only loud but not truly dangerous.
Has anyone out there had experiences with this problem? Or am I just
being paranoid about this?
Personally I'm thinking of creating a spring loaded diaphragm holder
that would blow out easily in the even this should happen. Any advice
would be most welcome as this is a really neat demo.
John Bowditch
-----Original Message-----
From: Informal Science Education Network
[mailto:[log in to unmask]] On Behalf Of Jonah Cohen
Sent: Friday, February 02, 2007 5:31 PM
To: [log in to unmask]
Subject: Re: A Song of Fire
ISEN-ASTC-L is a service of the Association of Science-Technology
Centers
Incorporated, a worldwide network of science museums and related
institutions.
************************************************************************
*****
FYI, the doohickey Jane refers to below (howdy n hi, yourself, Jane!) is
available from Flinn Scientific - they call it the "singing tube", and
you can get 1 or a set of 3 of differing lengths. Pretty sweet, and easy
to use with a small propane blowtorch from your friendly hardware store.
I suspect harder to engineer the much bigger tube with a row of holes
drilled into it. To this tube, you put a membrane + speaker on one end,
connect the other to a bbq-style propane tank, turn it on and light up a
row of flames out of the holes. Then, different pitches form visible
sine waves of fire. Google "Ruben Tube" and you'll find plenty of videos
of this on YouTube.
I fear that variables like tube length + diameter + material, plus size
of/distance between the holes will have to be precise, dagnabit.
Jonah Cohen
Outreach & Public Programs Manager
The Children's Museum
"If you hear only one song this year, there's something terribly wrong
with you."
-They Might Be Giants
-----Original Message-----
From: Informal Science Education Network
[mailto:[log in to unmask]] On Behalf Of Jane Snell Copes
Sent: Friday, February 02, 2007 3:39 PM
To: [log in to unmask]
Subject: Re: A Song of Fire
ISEN-ASTC-L is a service of the Association of Science-Technology
Centers
Incorporated, a worldwide network of science museums and related
institutions.
************************************************************************
*****
There's not much to it: a piece of schedule 40 pipe, a way to hold
it over a flame (ring stand with a heavy base and a clamp that can
get hot), and the flame. You can also use a piece of 4" stove pipe.
If you have a copy of Let's Try It, it's called the Hoot Tube. I've
seen them made with bits of screen wire poked in the lower end, but I
don't believe it's necessary. I used to work in the
high-temperature furnace field, and the "acoustic load" on
large-diameter, heated ceramic tubes is quite large--they can tear
themselves apart with the heat-induced vibrations.
We tried touring it with the Traveling Experiment Gallery (hi Jonah)
using a propane torch, but it was hard to ship the propane cylinder
and it seemed a bit hazardous with the general public. Cheers from
frozen Minnesota, Jane
>I'm looking into some demos on sound, and unsurprisingly was intrigued
>by the Ruben's Tube, a contraption hat displays sound waves using fire,
>as seen in this video:
>
>http://www.youtube.com/watch?v=UR8rZMKlIq4
>
>A quick google check reveals many similar videos, but little info. Does
>anyone have any schematics for building one, tips for usage/safety/how
>it works? We're hoping to build a version portable enough for outreach.
>
>Thanks.
>Jonah Cohen
>Outreach & Public Programs Manager
>The Children's Museum
>
>"On blind faith they place reliance,
>what we need more of is science"
>
> -MC Hawking
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