GTAW Process: Shielding Gas and Regulator Selection
There aren't many choices available for shielding gas selection in TIG. It's fairly straightforward. Pure Argon is the most popular and common shielding gas. Most people buy and use pure Argon in whether welding aluminum or steel. Unlike MIG, blends of CO2 and Argon cannot be used. If CO2 is used, it will contaminate the weld and will rapidly consume the tungsten. Often Argon can be contaminated with CO2 since the welding supply companies can use the same tanks to fill Argon and Argon blends. Helium and Argon are often blended, especially while welding Aluminum to increase penetration. Blends of Argon and helium are more expensive and some problems can be experienced since argon sinks and helium rises in the atmosphere. Also when too great of a helium percentage is mixed, arc starts can be erratic or make the arc unstable. The operator should be aware of which type gas is being used, because amp and flow settings will be different.
Not all regulators are equal. There is the floating ball type that visually regulates the gas flow and then there is the less expensive gauge type regulator. The floating ball is easier to see and read at a distance, and is a personal favorite. Both do a decent job of regulating the gas, but be sure to select a regulator that is calibrated for the gas or gas mix that you are using. Some will regulate both MIG gases and TIG gases. Some have dual or triple scales for several different blends. Blends high in helium require much higher flow rates. Also check whether the gauges are calibrated in Liters Per Minute (LPM) or Cubic Feet Per Hour (CFH).