liquid CO2 Is this on the level?

My son picked up a 110 Lincoln mig today. When he asked about an argon tank
the fellow at the counter said for his, he went to Pepsi and got liquid CO2.
Then he put on a dip tube to convert the liquid to gas. He told him it would
last 2 years everyday use. I told my son I never herd of doing it that way.
Is this on the level? Where can I learn about this process? While I am
asking for my son; if it is a good idea I may use the system for my own 110
mig.
Thank you for any direction
Greg W Murray
Reply to
Greg Murray
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How do you get liquid CO2?
I mean -- dry ice (a solid) usually sublimates directly to gas without going through a liquid state doesn't it?
-- you can contact me via
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Reply to
Bruce Simpson
All CO2 tanks hold liquid. Just a matter of how it's dispensed. Sounds like something got translated in the translation. Why not just go to the welding shop and get the right tank? mike
Reply to
mike
I don't have personal experience with MIG & CO2, but everybody says that argon-CO2 (C25) is much preferred. IIRC, pure CO2 gives you a lot more splatter.
As far as the dip tube, the counter guy has it backwards: a dip-tube is a tube inside the tank that goes from the valve to nearly the bottom of the tank. It "dips" into the liquid CO2. Using a dip tube results in liquid CO2 coming out the valve. Without a dip tube, the gaseous CO2 at the top of the tank is withdrawn. The liquid converts to gas just by using the gas. If you had a tank with a dip tube, you could use it for gas by inverting it. One place that I know dip tubes are used is for CO2 transfer. I.e., paint ball refill station - you want to transfer the CO2 as liquid.
Bob
Reply to
Bob Engelhardt
"Bob Engelhardt" wrote
The liquid converts to gas just by
Liquid CO2 changes from a liquid to a gas by the reduction of pressure.
Steve
Reply to
SteveB
SteveB wrote: Liquid CO2 changes from a liquid to a gas by the reduction of pressure. ^^^^^^^^^^^ In a closed tank, with both liquid and gaseous CO2, the pressure is determined by the temperature (usually the ambient temperature.) If the valve is opened, allowing some gas to escape, the liquid boils until the pressure comes back to equillibrium. There will not be an appreciable drop in tank pressure unless you are really drawing the gas off very rapidly.
Reply to
Leo Lichtman
You ned a high pressure to get liquid CO2. At atmosferic pressure you get dry ice as the temperature drops. Henning
Reply to
kofta
Everyone is posting about high pressure CO2 cylinders which is off topic of original post. Stores, restaurants and McD have changed over to liquid CO2 stored in vacuum container called dewar. Temperature in dewar is maintained below ambient and CO2 pressure is as high as 300 psi but normally 125psi to 90 psi in dewar. CO2 pressure less than 60psi in dewar will form dry ice. Pressure in closed CO2 cylinder with CO2 in both liquid and gas state is CO2 vapor pressure for temperature in cylinder. This is 500psi to 1300psi at temperatures that are shirt sleeve comfortable to humans. CO2 temprature/vapor pressure charts are on the web.
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Liquid CO2 dewar might not be practical for hobby welder but could save time and money for shop that uses lots of CO2.
Reply to
R. Duncan
Interesting. Sounds like you might save a few bucks if you employ incompetent people to manage your restaurant...which we all know is true for McD. Looks pretty much irrelevant for a hobby welding application that can't use the CO2 as fast as it boils off in the dewar. 2-years sounds optimistic.
mike
Reply to
mike
In the tank the CO2 is a liquid (at about 830 psi at 70°F IIRC), that is why you must weith it vs. use tank pressre to assess conntents remaining. Two types of tanks are common, one with a dip tube so liquid comes out (and becomes gas+solid upon depressurization) -- CO2 fire extinguisher cylinders are set up this way -- and regular type w/o dip tubes, the liquid boils and leaves as pressurized gas. For a given size both hold the same amount of gas. Propane and Nitrous Oxide (an anesthetic and an oxidiser for automotive engine short term performance boosting) also form liquids in their sylinders (though Propane does it at something closer to 120psi, and I forget the cyl pressure for nitrous.
dry ice as the temperature drops.
Reply to
The Masked Marvel
A normal CO2 tank has liquid CO2 in it at a fairly high pressure. If it is a fire extinguisher there is a tube that goes to the bottom of the tank so you get liquid CO2 out. You want the bottle without the tube. Straight CO2 is not as nice to use as a argon /CO2 mixture for welding , but it is cheaper. Some Dual shield wires are designed to be used with straight CO2, but will still be better with argon/ co2 mixture.
Dan
Reply to
Dan Caster
In message , Dan Caster writes
Hi Greg,20 years ago most production MIG welding was done with Liquid CO2 cylinders.We used Dip Tube cylinders,the reason being that there is a small amount of moisture in the cylinder.If you do not use a dip tube then you draw off gaseous co2 and the resulting liquid inceases in moisture content.A dip tube draws up liquid at a constant composition which then converts to gas and flows down the MIG torch.A CO2 Heater was placed on the cylinder to prevent the regulator freezing up.It gave perfectly sound welds but produced more spatter particular at the higher current levels-250A plus.Also with CO2 it was difficult to go into Spray transfer. Following these reasons and argon/CO2 becoming more available and therefore cheaper,the use of straight CO2 diminished
Reply to
Gwyn Phillips

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