Rolling your cylinder

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Anyone ever hear of gases separating when they sit for long periods of time?  Someone told me you need to lay the cylinder on the ground and roll it to mix the gas up?  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Have we all gone mad?
Reply:i prefer to lock it in my pneumatic paint shaker for 20 minutes.225NT bobcatAEAD200LEScott 125mm175, mm252 w 30A, PT225mm211, TA 181iHyper Therm 380, cut master 529100X & XX, Digital Elite6 Victor setssmith little torch, meco midget kalamazoo band sawsteel max saw evoulution circular saw
Reply:The guy that told me this is a great long time tig welder that has worked for big companies........I told him he was full of it when I told him about the bad gas cylinder I just got and he said lay it down and roll it around.........  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Just because they've been doing it a long time, doesn't mean he knows what he's talking about.Have we all gone mad?
Reply:I think some people missed high school science completely.  Look up brownian motion on google.  Unless maybe you store your gasses at absolute zero... Ha ha
Reply:I could theoretically believe this, with a cylinder of C25 - where CO2 could liquify, and settle out of the mix as the liquid portion would be a different density  than the argon gas.       However, if that was the case, I would also think that once Ar and CO2 are mixed, that would occur immediately, so there must be some other forces at work to maintain the mix of these products in the cylinder?      If I understand right, CO2 is a liquid at pressure greater than 900 psi - so if mixed with Ar in a cylinder, would it just separate out in the cylinder as a liquid?    However, CO2  must be lighter than Argon - since a 250 cubic foot cylinder of  100% Argon has a content weight of  25.85 pounds, while a 250 cf cylinder of Ar/C25% has a weight of 13.27 pounds.      My problem is I know just enough about gas behavior to consider questions.    Now I'm confused?
Reply:*If* both gasses are liquid in the tank and they have different boiling points, then the evaporated gas will have a mix ratio different than the liquid (see distillation).  And the ratio in the mix will change as you use up the tank.  BTW, shaking and mixing doesn't help.However I don't think this applies in welding situations.  Yes, the CO2 is liquid and it's evaporating, but it's only CO2 so there's no distillation separation.  The C25 is argon and CO2, but I don't think there's enough partial pressure to liquify the CO2, so again, no distillation separation.Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:The Internet holds the answer  - http://en.wikipedia.org/wiki/Partial_pressureFrom this wikipedia web site:In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture.Argon and CO2 are both identified as ideal gases.
Reply:Get someone to help you shake it until you hear the marble inside! Sorry bud could'nt resist   I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:I use the Fat Chick Method. Insert cylinder in body piercing, secure with cargo strap, and let Love stir the gases.
Reply:Originally Posted by farmallI use the Fat Chick Method. Insert cylinder in body piercing, secure with cargo strap, and let Love stir the gases.
Reply:Originally Posted by farmallI use the Fat Chick Method. Insert cylinder in body piercing, secure with cargo strap, and let Love stir the gases.
Reply:Originally Posted by jbmprodsjust be sure to pm us all so we can be sure to duck for cover when the gas escapes
Reply:Originally Posted by weldermikeGet someone to help you shake it until you hear the marble inside! Sorry bud could'nt resist
Reply:just wrongLast edited by jbmprods; 04-11-2012 at 05:24 PM.225NT bobcatAEAD200LEScott 125mm175, mm252 w 30A, PT225mm211, TA 181iHyper Therm 380, cut master 529100X & XX, Digital Elite6 Victor setssmith little torch, meco midget kalamazoo band sawsteel max saw evoulution circular saw
Reply:Hey, you wanna buy a elevator pass ????
Reply:When you roll your tank don't leave it laying on it's side, it will develop a flat spot.Beer has food value, Food has no beer value
Reply:When you roll your tank don't leave it laying on it's side, it will develop a flat spot.
Reply:Well, my secret is out now. I use a Helium/Argon mix bottle. When I want Argon, I turn the bottle upside down.  When I want Helium, the bottle goes right side up.Two turn tables and a microphone.
Reply:Originally Posted by PangeaWell, my secret is out now. I use a Helium/Argon mix bottle. When I want Argon, I turn the bottle upside down.  When I want Helium, the bottle goes right side up.
Reply:Originally Posted by PangeaWell, my secret is out now. I use a Helium/Argon mix bottle. When I want Argon, I turn the bottle upside down.  When I want Helium, the bottle goes right side up.
Reply:Originally Posted by CEPSeriously, will that work? Which way would I turn my C-25 if I just wanted CO2?
Reply:Originally Posted by BD1Hey, you wanna buy a elevator pass ????
Reply:Originally Posted by zapsterTry it and be sure to post pictures......zap!I'll put it on my list of things to remember.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Did some asking around today (gas manufactures locally ) the only cylinders that  are laid down and rolled are Argon/CO2  because they do separate with time, so I learned something new from a guy that paid attn during his 35 years in the trade....  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Originally Posted by B_CDid some asking around today (gas manufactures locally ) the only cylinders that  are laid down and rolled are Argon/CO2  because they do separate with time, so I learned something new from a guy that paid attn during his 35 years in the trade....
Reply:The Praxair Starblend eductor tube:http://phxwelding.com/mixedgases.htmTo address this issue, a popular practice is to “roll” the cylinders to mix the gases. This procedure does not guarantee mixture homogeneity, and is difficult, if not impossible, to do.
Reply:Shouldn't this thread have been started on the first of the month?
Reply:well i still like my idea of the paint shaker. i must say Farmall, that is one fine looking specimen of the of the female persuasion. i have a soft spot for wookies. is it closing time yet?225NT bobcatAEAD200LEScott 125mm175, mm252 w 30A, PT225mm211, TA 181iHyper Therm 380, cut master 529100X & XX, Digital Elite6 Victor setssmith little torch, meco midget kalamazoo band sawsteel max saw evoulution circular saw
Reply:Originally Posted by k45Shouldn't this thread have been started on the first of the month?
Reply:Here's another one you might not know about.  When SMAW always put your rod in the stinger with the numbers facing the top or it won't weld properly.Trailblazer 302Hobart Stickmate AC/DCLincoln SP 135 TSmith torchSpoolmatic 30A
Reply:Originally Posted by shortarcHere's another one you might not know about.  When SMAW always put your rod in the stinger with the numbers facing the top or it won't weld properly.
Reply:About 3000 psi and 30 degrees C is well beyond the "critical point" for argon. In a cylinder it exists as a so-called supercritical fluid. (What that means is the density of, and physical properties of liquid and gas are identical, at a certain pres. and temp..)In the case of pure CO2,  at 3000 psi it will exist as a liquid. However, I assume it can freely dissolve in the supercritical Ar. I'm far from any kind of expert on the chemistry of supercritical fluids. This is about all I know on the subject. The main issue would be, the difference in density between the two would mean they wouldn't mix immediately when they were added to the cylinder in sequence.If the cylinder were allowed to sit for several days after being filled, I imagine the CO2 would have enough time to completely dissolve.Rolling might help that, or it might not.Many, but not ALL cylinders used for mixed Ar+CO2 are equipped with an "eduction tube." The purpose of this is to introduce the gases from bottom-up rather than top-down.Very occasionally my shop gets a bottle of pure CO2 (500~600 psi) with an eduction tube in it which wasn't properly labeled as such.  (At this pressure CO2 exists as mixed liquid and gas, like an aerosol can.)  So liquid in the bottom gets sucked into the flowmeter instead of gas at the top. when the press drops to around 30-40 it flashes into dry ice. If you want to have some fun, you can take off the flowmeter, unscrew the valve just slightly, and make a dry snow storm.
Reply:Not completley impossible to have gas separated in the cylinder.  95% of the time it is due to poor filling procedures.  You generally add CO2 first, and then fill the balance with argon.  If you do not have a dip tube, the argon can stay at the top of the cylinder (atomic wt 40 vs 44 for CO2).  This is usually only a problem if the cylinder is filled fairly slowly.  The other instance I am familliar with is if you have a high % of CO2 (say 50%) and the cylinder is filled to 2400/2640 psi.  If the temperature drops pretty low, you will get liquid in the bottle.  you can roll the bottle around and watch if get frosty as the liquid CO2 warms up and turns back to a gas.  If you have a dip tube, and you fill at the appropriate speed, the argon shoots down the tube and mixes properly with the CO2 as it gets all stirred up.  Once mixed, the gas will tend to stay mixed.Experience is something you get right after you need it
Reply:And I thought BC was posting pics of him kicking some steel.
Reply:Ok   let's put this to rest, or fire up a new arguement http://findarticles.com/p/articles/m.../ai_n27565579/  See the section addressing rolling cylinders to maintain the mix.Another, and apparently common way, is a stratified withdrawl tube perforated at various "altitudes".  I guess this is the industry standard, dunno.http://phxwelding.com/mixedgases.htmOther articles suggest that only manifold mixed gases are really correctly mixed at the point of use.  Big shrug, again I dunno.I just grab a stick out of the can and forget about the whole thing "Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by farmersammI just grab a stick out of the can and forget about the whole thing
Reply:Originally Posted by jbmprodsi prefer to lock it in my pneumatic paint shaker for 20 minutes.
Reply:Originally Posted by shortarcHere's another one you might not know about.  When SMAW always put your rod in the stinger with the numbers facing the top or it won't weld properly.
Reply:Originally Posted by B_CAnyone ever hear of gases separating when they sit for long periods of time?  Someone told me you need to lay the cylinder on the ground and roll it to mix the gas up?
Reply:Originally Posted by nogoaAfter it is shook you should pound the tank top with a hammer, sorta like tapping a coke can, so you dont get foam in your hose.
Reply:Originally Posted by CEPSeriously, will that work? Which way would I turn my C-25 if I just wanted CO2?
Reply:From one of the articles:"Charging a conventional cylinder with two or more component gases can cause a discrete stratification of the individual gases (Fig. 1). However, even in the absence of convection they will eventually mix, through a process called interdiffusion. The interdiffusion co-efficient is a transport property of the gas system. It reflects the fact that different concentrations of gas tend to equalize as their molecules strive to disperse uniformly."Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:Why wouldn't the truck ride on the ride over be enough to mix the gas. Maybe too many right turns/ Have to add a few lefts?