There may be hard fast rules for the things I'm about to describe but all I know is the way I've been doing it for the last forty some-odd years, so that's what I'll describe.
With the gages mounted on the tanks turn the regulator handles all the way out. Turn the tanks on then set the oxygen regulator to 10 psi, and the acetylene regulator to 5 psi.
To light the torch turn the acetylene knob on about a quarter of a turn and light the acetylene. Turn the knob up and down and notice how it makes black soot when turned low, and burns clean when turned up. Set the acetylene to the place where it just begins to burn clean, then turn the oxygen knob on a bit. Play with the oxygen knob and notice the three distinct flame areas. Right at the tip there is a small bright blue cone. Beyond the bright blue flame is a less bright but still blue area. The third and outer most flame area is yellowish and more ragged. Watch the two blue fire cones and set the oxygen to the place where they just meet. If the flame still shows a haze of the lighter blue cone it is called a carbonizing flame, and that's OK. If the oxygen is adjusted past the point of conjunction it is called an oxidizing flame, and that will give you trouble. So basic rule. It is better to have a slightly fuzzy carbonizing flame than a sharp outline oxidizing flame.
When brazing we use the torch like a small paint brush and not like a spray can. The beginning mistake always made is having the torch too far away from the work. Generally the blue cone should be about a quarter of an inch or so away from the metal to be brazed. Get in, and get out. Do not brush the torch over the metal unnecessarily or you will soak the metal with heat and the phos will run everywhere. The phos will follow the heat. We control the phos by controlling the heat. If you see the work getting away from you get the torch away from the metal and let it settle down a bit, then go in and try again. Keep a spray bottle at hand to cool the work when necessary.
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