Recommended max acetylene withdrawal rate reduced by CGA

[John Clay]

The Compressed Gas Association has apparently revised the maximum recommended withdrawal rates for acetylene down from 1/7 cylinder capy per hour to 1/10 for intermittent use and 1/15 for continuous use. This short article is worth reading:

http://www.thefabricator.com/article/safety/fuel-your-safety-knowledge

I now realize that I've been exceeding the old recommendations, never mind the revised ones. Since I have recently grown to appreciate a rosebud for the large items it looks like I'd need a 300 cf cylinder. For that reason I switched to LP for lugs, crowns, BB shells. My 75 cf Acetylene cylinder is only for the smaller tips and frame items now.

John Clay
Tallahassee, FL

[Eric Keller]

John,
Thanks for pointing that out, I never would have heard it otherwise.
I'll have to revisit this with my larger tips
Eric

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[Alistair Spence]

Good link John, thanks for that. 

I think that the weak link in the chain of information in this matter is just how much acetylene is being drawn off at a given regulator pressure and welding tip orifice size. I've poked around on the Victor website and found some numbers that give a vague range, but the information could be made easier to find, and more coherently presented (imo). Maybe other manufacturers present welding tip flow data in a more helpful way?

Alistair Spence,

Seattle, WA.

[John Clay]

I think that's an excellent point Alistair. Can you post links to what you've found?

Even one hard data point, like  flow rate at X delivery pressure and Y turns (say, max useful/acceptable torch valve opening) of the fuel valve would be helpful.

I'm somewhat in luck with the larger tips in that I drive them hard so I'm pretty sure I'm operating in the neighborhood of the max flow rate values given. Based on that, and a comment you made a while ago about flame behavior when acetone is entrained in the fuel flow, the light went on and I realized I was probably operating outside of withdrawal recommendations; well outside most likely. 

John Clay

Tallahassee, FL

--

John

[Alistair Spence]

Sorry John,

all the links I saved w.r.t this have gone bad. The Victor website was not the best in the first place, with a slew of PDF's to choose from. I had to sift through a bunch of them to find what I was looking for, but Victor has undergone reorganization since then, and the website is all different now. The links have gone bad.

Here's a link to the current literature page, http://www.victortechnologies.com/victor/resource-center/literature.html

There's a drop down menu to select different categories of literature. Here's a link to a document under the "Safety information" tab,

http://victortechnologies.com/IM_Uploads/DocLib_4711_Cutting%20Heating%20Welding%20Guide%20(0056-3260)__Sept2009.pdf

If you download that and scroll down to section 9 (Specifications), page 42, you'll see a table that gives some flow info. It's been a while, but I believe that this is the same data that I've based my previous back of the envelope calcs on. As an aside, I have called Victor in the past, when I was struggling to all figure this out and spoke to a very helpful fellow, an engineer or technician of some kind. He was quite willing to walk me through it, and had access to info that wasn't on the website. 

Anyway, that's my 2 cents.

Alistair Spence,

Seattle, WA.

[John Clay]

Some practical reference data is available in posts 22 & 23 of this thread: http://www.velocipedesalon.com/forum/f10/minimum-acetylene-tank-size-frame-building-38310-2.html

John Clay
Tallahassee, FL