Compressed gas cylinder questions

I've obtained some old carbon dioxide cylinders which I plan to use as bells. And while the task doesn't seem too troublesome, I had some questions that may or may not help me before I start. Is there a web page anyone knows of that lists all sorts of factoids about gas cylinders? Like how to determine the metal composition (most specifically what grade of steel), what the thread sizes in the neck commonly are, common wall thicknesses, stuff like that?

Also, any suggestions on the easiest way to cut them? Oxyacetylene, plasma, bandsaw? As the cylinders are quite large (about 9 inches in diameter) I don't think a bandsaw will be happening as I'd need a rather large bandsaw, probably horizontal, and one that big is beyond my means. I was actually thinking about maybe constructing a device that holds the cylinder on two rollers and spins it such that I could even use a parting tool from a lathe. Has anyone done this before, and maybe have some experience they can share with me? Thanks!

Reply to
The Hurdy Gurdy Man
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Hi, I cut off an old oxygen cylinder than somebody had given to me to make a bell. Without going and measuring it, I would guess it was around 7" diameter and

5/16 wall thickness. I cut it in a horizontal bandsaw. No ptoblem; just like cutting pipe. Some sort of carbon steel.

I had expected to be able to tune the bell by adjusting the length. I started out with almost the full length and cut it down in several steps. It did not seem to make a lot of difference. I am still not sure I understand why. Ended up with about 18 inches long.

Threaded hole is standard 3/4 NPT if I recall correctly.

Mill

Reply to
MP Toolman

It depends upon your budget - doesn't everything? For cheap use a cut-off disc in an angle grinder. Pretty fast, pretty clean. Fastest, cleanest, and most expensive is plasma. Bob

Reply to
Bob Engelhardt

MP Toolman wrote: (clip) I had expected to be able to tune the bell by adjusting the length. I started out with almost the full length and cut it down in several steps. It did not seem to make a lot of difference. I am still not sure I understand why.(clip) ^^^^^^^^^^^^ I would have thought the same thing, but since the length seems not to matter, it must mean that the resonant frequency you hear is related to the circumference. In other words, the going back and forth from round to oval to round....

Reply to
Leo Lichtman

If this were true, it seems then that the cylinders I have would all have roughly the same pitch when struck since their wall thicknesses are all the same and their diameters are all the same, but their lengths are different. However, I can assure you this isn't true at all. The longer the cylinder, the lower the pitch. I guess I'll find out for certain once I start chopping the things apart and attempting to tune them. I do think the length matters in that you get that whole "bass tube" effect with a longer tube... not that I'm well experienced in acoustics or anything, so I'm basically just talking out my behind on this one. Still, the longer cylinders do have a noticably lower pitch. I'm thinking about documenting the project on a web page, so perhaps I'll post my findings.

Reply to
The Hurdy Gurdy Man

These cylinders are most definitely not 3/4" NPT. They look more like a straight thread, with diameters ranging from 1 to 1.25 inches. Thread count looks like it's anywhere from 13 TPI up to maybe 20 TPI. But a 3/4" NPT threaded pipe would fall right through the hole if I were to try threading it in there. I'm assuming oxygen bottles would be of a different design than a carbon dioxide cylinder, though. I've heard that compressed oxygen has some different needs, especially with things like what sealants can be used and whatnot.

I've looked around for resources to decode the various markings on the bottles but have had no luck so far, mostly because I'm not sure what keywords to use when searching online... all the obvious ones send me to manufacturer advertisement pages or mil-spec descriptions for decoding markings that don't exist on these particular cylinders. They are all embossed with the letters 'USN' followed by a long numeric string, and then suffixed again by 'USN'. Can't say for sure that they're US Navy cylinders or anything like that, though, even though they're surely painted the right color. And according to the person who gave them to me, the oldest of the cylinders was created around 1945. Definitely past their prime!

Reply to
The Hurdy Gurdy Man

Actually from oval one way to oval the other. (at 90 deg ) ...lew...

Reply to
Lewis Hartswick

Reply to
Grant Erwin

I have a CO2 cylinder that I was considering converting to a welding gas, so I tried to find specs on the threads. What I found was the above sort of thing (concoa) which specifies the _output_ thread, but not the input/tank thread.

BTW -my CO2 tank thread is 1 1/8 - 12, straight (NPS?).

Bob

Reply to
Bob Engelhardt

Leo wrote: (clip) In other words, the going back and forth from round to oval to round.... Lew wrote: Actually from oval one way to oval the other. (at 90 deg ) Leo now writes: Lew, that's kind of what I had in mind, but now I'll carry it a step further. I don't believe the angle is always 90 degrees. It can be off a fraction of a degree, so the major axis of the ellipse "precesses."

Reply to
Leo Lichtman

There are also multi lobed modes too. jk

Reply to
jk

:-) lew now writes. :-) Yes due to friction(damping) losses in the material. ...lew...

Reply to
Lewis Hartswick

jk wrote: There are also multi lobed modes too. ^^^^^^^^^^^^^ The typical sound of a cylinder ringing is rich in harmonics, which means that is must have several multi lobed modes.

Reply to
Leo Lichtman

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