The Patented Furick FUPA #12 has an inside diameter of .750 inches/ 19mm and is recommended for DC polarity applications only, it uses anywhere from 20-30 + CFH of Argon flow. It is recommended for 3/32 / 2.4mm tungsten size and carries a 180 amp rating on constant amperage. It can go higher if using pulse settings. The added strength of the FUPA 12 ceramic cup allows for walking of the cup technique.
Fupa 12is recommended for Mild steel, Stainless steel, Chromoly, Titanium, Inconel and other space grade alloys. It works best on thinner / smaller applications such as header tubes and chassis tubing.
It is recommended that you keep the diffuser the shape it comes and you remove and reinstall if it gets out of shape. Also it is recommended with all the BIG Diffuser cups that the user start off on low amps to stabilize the arc as to make sure you will not arc off diffuser. If diffuser arcing occurs you will have to clean/regrind the tungsten. You will not hurt the diffuser on low amps but if arc with high amps you can deteriorate the diffuser.