Looking at a Miller Econotig... the one that comes with "everything you need to TIG weld except for gas and electrodes".
These gas cylinders come in 20, 40, 80, etc cf. from what I can see.
How long would a 20 last? A 40? I don't want a larger (or more expensive) cylinder than I need (have a SMALL workshop) but I don't want to be running back and forth to the gas supplier all the time either.
Advice gratefully accepted.