Mig mix gas running out?

[Dave C]

Tried searching but got no results. I'm a hobby welder and yesterday my Mig welds have gone to crap. Looks like welding with no gas. Gage on the flowmeter shows the tank is pretty low but not empty. Steady flow with trigger on is 20 cfm. Is the gage lying or is something else going on? The tank was last filled in 2017. Does the gas go bad after that long? Maybe I should just go to Airgas and swap for a filled bottle.

[Willy]

Have you verified that shielding gas is indeed coming out of the nozzle when welding?
Turn the wire feed down or loosen the drive roll and pull the trigger to see if the gas is coming out. You should be able to hear, and or feel the gas coming out a 20 cfh.
Could be a regulator problem, gas solenoid, gas diffuser blockage, etc. Try to narrow it down.

[Captain K]

Make sure your nozzle is clean. Check all the connections in the gas line including where the diffuser screws into the gun. Check the oring at the back of the nozzle too, can suck air in there and spoil the weld. Door open or fan on? Doesn’t take much wind to make a mess

[LKeithR]

Check the things already mentioned for sure but to me it sounds like you're just out of gas. Tanks will do funny
things when they are nearly empty. You shouldn't fully empty the tank anyway. If you completely drain it then
it must be purged before it can be filled again. Obviously there are no hard or fast rules about this; it's just a
courtesy/protocol that most professional weldors try to follow...

[MrWhoopee]

Something similar happened with my TIG. After getting a replacement bottle of gas, I discovered damage to the hose.

[Dave C]

Glad I posted this, so thanks to all for responding. I will definitely check the gas line and the torch to be sure gas is comming out at the weld. The welder has been idle for a year or more so all that was suggested is possible. Will post back when this is all figured out and fixed.

[garyhlucas]

I used to have a partner that sold welding gasses. It is possible that if you are using c25 that the CO2 and Argon have separated and you are getting only Argon. Roll the tank back and forth on the floor to see if it will mix. I have heard of gas dealers doing this if they make the C25 on site.

[Willy]

I used to have a partner that sold welding gasses. It is possible that if you are using c25 that the CO2 and Argon have separated and you are getting only Argon. Roll the tank back and forth on the floor to see if it will mix. I have heard of gas dealers doing this if they make the C25 on site.

Very good point!

[LKeithR]

If you have problems after starting a new bottle of gas chances are the gas is "skunky" or contaminated.
This often happens because the previous user of the bottle drained it right out and it wasn't properly
purged before being refilled. Over our 50+ years of running a welding shop my brother and I had many
bottles that were bad. When that happens you just return them and get a new bottle--never had an issue
with the gas provider; they know it happens from time to time...

[BigMike782]

If you get a cylinder that is not vented, vacuumed and then filled you need a different gas supplier.

[Dave C]

I haven't had a chance to check the welder over, but had to go to town yesterday, so stopped by NexAir and swapped my bottle for a full one. Geeze Louise, I was shocked at the price. A hell of an increase from what I paid a few years ago. $51.01 then vs $86.45 now. I may have to stop doing welding favors for friends and neighbors.

[BigMike782]

Or leave the invoice on the cylinder so you remember that it’s nice to help people but it has a cost.

[LKeithR]

If you get a cylinder that is not vented, vacuumed and then filled you need a different gas supplier.

It's always been my understanding that it's best to leave a little pressure in the tank and that as long
as that pressure is there, there is no need to purge the tank before filling. However, I have never been
to a refilling plant so I can't say for sure.

Our "supplier" is a local independent welding supply company but their gas comes from a Linde plant
in the Seattle area. We do get the occasional bottle of "skunky" gas, just goes with the territory...