Back-purging SS with C25 instead of Argon

admin

I've never TIG'ed stainless before and would like to know if I can back-purge with a different gas, specifically C25 on the backside when I'm welding with Argon on the front. The reason I ask is that I have only one outlet on my Argon tank regulator which runs into the Syncrowave itself.  But I've got a second tank of C25 on my MIG that would be easy to use for backpurging if it won't cause problems.  What sort of setups do others use to back-purge?  A Y-fitting on the hose running from regulator to the machine and just increase pressure to account for the loss going to the back-line?  Or a complete second tank?  Or are there regulators with a 2nd outlet for this purpose?  Any advice would be appreciated.Thanks,Lincoln AC225 & MigPak 140, Lincoln Magnum SpoolGun, Miller Spectrum 375-X Plasma, Syncrowave 200 TIG, Millermatic 252 MIG, Miller Digital Elite, General 7x12" horiz/vert bandsaw, 3' box/pan brake, 20 ton press, milling machine, 12x28 lathe, etc.
Reply:Hello aquafire, the simple answer is no. If a back-purge is required the preferred gas would be argon. Do you have the option to install a splitter off of your argon tank? Depending upon your requirements, you might be able to use Solar Flux for backing to avoid sugaring. Best regards, Allanaevald
Reply:Don't backpurge with C25.  Use Argon.  Get a 2nd tank or buy a splitter.  You might be able to use the regulator from your MIG setup.  Doublecheck that it's a flowmeter; if so, just swap it over.There are 2 kinds of splitters you can use.  The first type is installed after the flowmeter.  Usually has 2 valves so you can shut off the back purge when you're not using it.  This is a low pressure fitting and the cost will be lower as a result.  The disadvantage to using this type of splitter is you don't have good control over the flow rate to either side.  You need 15-20 CFH for your TIG torch, and about 5 CFH for the backpurge.  Too much back purge will cause problems when it's time to weld the root shut.  You'll have to fiddle with the valves to try and balance the flow rates so the torch gets enough gas and the backpurge line doesn't get too much gas.The 2nd type of splitter is installed between the tank and the flowmeters.  It's a high pressure fitting, so the cost will be higher(I guess about $30-$40).  This type of splitter will let you hook 2 flowmeters to the same tank.  Then you can dial each one in to the correct flow rate.  I have this type and it works well.  I just shut off the flowmeter on the backpurge side when I'm not using it.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Thanks guys- some great advice.Lincoln AC225 & MigPak 140, Lincoln Magnum SpoolGun, Miller Spectrum 375-X Plasma, Syncrowave 200 TIG, Millermatic 252 MIG, Miller Digital Elite, General 7x12" horiz/vert bandsaw, 3' box/pan brake, 20 ton press, milling machine, 12x28 lathe, etc.