c25 tank

[hounddog]

i have 2 , probably stupid ?,s do the tanks themselves have a stamping in them to let you know how big the tank is? and last ? when you have your guages hooked up one quage tells you tank pressure and the other one tells you what pressure you set gas to go to welder, how do you know when the tank is near empty? im sure by the tank pressure , but what pressure will i t be at when nearly gone?

[MAC702]

what pressure will it be at when nearly gone?

No such thing as a dumb question. Unlike acetylene, take it all the way to zero. Remember that it reads "gauge pressure," not absolute pressure; it is a relative pressure compared to the atmospheric pressure of your location.

[Pumpkinhead]

MAC,
Zero?, probably not that low, how 'bout till the reg. no longer functions.

[hankj]

Hounddog,

Some tanks may have a capacity stamp; some tanks don't! If there is one, it's normally in the first line of stamping on the neck ring. The actual tank volume really won't tell you it's capacity for all gases, since they vary in density, but most gas suppliers mark the fill volume on the tank (ahhhh..not all the time, though!).

You can keep running your C-25 until you can't keep the flow rate set to where you want it. Then, it's time for a fill!

Out of the 7 different tanks I have, only ywo are stamped with the volume! If you go to www.airgas.com they have a nice chart that gives tank dimensions and volumes.

Hank

[MAC702]

MAC,
Zero?, probably not that low, how 'bout till the reg. no longer functions.

The high-pressure side will read zero for some time before the low-pressure side is insufficient for use.

[Pumpkinhead]

Awww, come on now MAC, that's semantics, do you really think a H-P guage is going to have a fine resolution?
the face would be gigantic !

[MAC702]

Sure, PH, but I thought it really answered the guy's question. I thought he was asking if he took his tank down to zero, or if he should still be having a reading on the HP gauge when he exchanged it. Semantics aside, I take mine to zero and then use whatever it'll give me afterwards sometimes, at least until a convenient time to swap over the tanks.

But, yeah, its "zero" ain't yet zero.

[BigEd_36]

No such thing as a dumb question. Unlike acetylene, take it all the way to zero. Remember that it reads "gauge pressure," not absolute pressure; it is a relative pressure compared to the atmospheric pressure of your location.

How far down should acetylene be used? Why not use it all?

Ed

[hankj]

How far down should acetylene be used? Why not use it all?

Ed

If acetylene was stored as a plain ole' compressed gas, like oxygen or argon, then no sweat.

Because acetylene is stored saturated in acetone in a porous filler inside the tank, the possibility exists (probabilty, actually) that attempting to withdraw the gas at pressures lower than 15 PSIG will result in liquid acetone being drawn from the tank.

The same thing may happen if you try to draw more than 1/7 of the tank volume out per hour. Here's a read:

Acetylene

Acetylene (C2H2) as packaged for welding is safe if handled correctly and used as intended. Acetylene becomes very shock-sensitive when compressed to pressures greater than 25 PSIG. To allow storage at higher pressures, welding acetylene tanks are filled with a porous “sponge” which is saturated with liquid acetone. Acetone will absorb acetylene gas at a rate of 1/7 of its volume per hour. The solution of acetylene in acetone is stable at higher pressures. It takes 7 hours to fill an acetylene tank.

By the same token, the gas can only be withdrawn from the tank at the same rate as it was filled. Attempting to withdraw greater than 1/7 of the tank volume for more than a few minutes will result in liquid acetone being withdrawn from the tank. Liquid acetone will quickly eat away the diaphragm of the acetylene regulator, allowing liquid acetone at full tank pressure to enter the hoses and torch.

Acetylene discharged into air (or an oxygen/acetylene torch) at pressures greater than 15 PSIG may cause the gas molecules to disassociate, resulting in free hydrogen gas, which is highly explosive. That’s why the “red line” on acetylene gauges is 15 PSI!

When transporting acetylene tanks, they should remain upright. If they are laid down for any reason, they should be allowed to remain upright for at least 30 minute before use.

When deciding what tips or multi-flame (rosebud) heating nozzles to use, be sure that the hourly consumption rate in cubic feet does not exceed 1/7 of your tank volume. Large (#8 and larger) usually require a manifold array of acetylene tanks to provide the required volume.

Hank

[Pumpkinhead]

But, yeah, its "zero" ain't yet zero.

Fair enough MAC, it is just funny to think about some skinflint wringing the last gasp of gas out of his bottle. it's not economical to me to have 3-4 "almost" empties and switchin' 'em out to get every pennys worth or be coming down to the bottom and figure "oh, i have enough" then the holiday weekend is chock full o' work and i ain't got the gas. no sir, if i have to tithe a bit o' gas to my supplier so be it.

[BigEd_36]

Wow! Thanks Hank, I did not know that. I will not be running my acetylene tanks under 15 PSI! I think I've done that before, guess I got lucky, but I'm not going to be pressing my luck in that fashion again! Now I'm wondering if I've done any damage to my regulator, might be time for a new one.

Ed

[hankj]

Wow! Thanks Hank, I did not know that. I will not be running my acetylene tanks under 15 PSI! I think I've done that before, guess I got lucky, but I'm not going to be pressing my luck in that fashion again! Now I'm wondering if I've done any damage to my regulator, might be time for a new one.

Ed

You have to be pretty flagrant in the violation. Both overdrawing in fow rate and trying to suck 'er dry can result in acetone flow. If you don't have any requlator troubles now, I'd bet you didn't suck in any acetone.

When I got my first rig, I didn't know about any of this either. I was very lucky, since I had a "B" tank and used to use a #4 Victor welding tip to heat with! I skated because I never needed to run it very long - 6 or 7 minutes tops. But, I now know that if I had tried to run it fo half an hour preheating some big chunk of steel, I most likely would not have it still!

For those reasons, I try to share the 1/7 rule and the rest of the acetylene story with everyone who asks a question.

Hank

[BigEd_36]

Well, after reading Hankj's explanation on acetylene, I decided it was time to take the plunge that I had been considering for some time. I had been considering changing my torch over to a propane setup, due to the lower cost of propane, and propane being safer. I don't gas weld, and I can't remember when I last had the occasion to braze anything. I had recently read posts (on this forum or one of the other welding forums) considering the hazards of the flame front traveling back up the hose to the tanks with a malfunction, and my old Harris setup that I've had since '71 doesn't have any flash arrestors. With the upgrades that I wanted to do to that ol' setup, and the changes needed to use propane (grade T hoses, propane tip), seemed like it would be about as cheap to get a new setup (or at least it gave me a good enough excuse!). Figured this time around I would go with a Victor rig, since parts and tips are EVERYWHERE for them. Hit a "Buy It Now" on EBAY from IOC & got a Victor SuperRange II setup coming for $24 less than I could buy the Victor Performer (lighter duty) setup locally. It should be here this week, and it will be going on propane.

Thanks for the knowledge that you guys share!

Ed