[sammyg2]

Acet. gets set between 5 and 7 psi. Valve cracked open, no need to go much more than that, never exceed 15 psi or you will draw up some liquid which is bad. Don't lay the bottle on it's side and use it. if you have to lay it down, let it stand upright for a while prior to use.
Lack of oxygen is what makes the soot. Check your oxygen, should be set around 20 to 25 for most stuff. O2 valve on bottle should be wide open or completely closed, no inbetween.
Don't use any oil or lubricant on any O2 fittings.