Welding Tips and Tricks

Does a gas mix like C-75 which is 75% Argon and 25% CO2 separate in long-term storage? I have a large gas bottle that lasts a year or two and on days when I think I don't really know how to weld, I wonder if something has changed the gas mixture so I get straigt Argon? What do y'all say??

(I pasted a copy of this reply to your duplicate question on the MIG forum.)

You would think so, but no, not really. The molecular motion (heat) that keeps it a gas keeps it pretty well diffused. CO2 is heavier than Ar, of course, so there is a variation in the ratio between the top and bottom of the cylinder, but as soon as you begin drawing gas, you begin mixing the contents of the bottle.

Consider the manufacture of these gasses. Air is cooled in stages to the liquid state of each gas to get them to condense in a fractional distillation column. This is a very energy-intensive process, yet is far more efficient than separating them by weight in a centrifuge.

I've been welding almost 30 years, and I still have off days. Some days a pipe weld looks like a "wedding band", some days more like an ugly divorce.

Steve