There are several schools of thought on temp settings for your volcano vaporizer.
The active ingredient in popular herbal mixtures vaporizes when heated to between 338 F and 372 F. This is not hot enough for the plant material to burn so many of the toxins associated with smoking are not released.
On the original Volcano vaporizer, this range is between 4.25 and 6.
Some folks prefer a lighter less dense vapor – they’ll set at 5.5 and get a very light mist in the bag, and probably get more bag fillings.
If you prefer a “smokier” experience, start at 6.5 and ratchet it up a notch with each successive bag filling.
How do you know when it’s done? Depending on the quality and the quantity of the material in the chamber you may get 4-6 bags of vapor. You’ll notice a change in taste and the density of the vapor mist in the bag.
IMHO, anything above 6.5 you might as well be smoking the stuff. I’d rather get nice tasty non-lung irritating bags and save my leftovers.