We use a method for cutting down fire scale when using a Presto-Lite Torch along with an acetylene B tank.
The torch tips are engineered to take in so much gas through the gas orifice and so much air through the air inlet ventura so they burn to their max. heat which is an oxidizing flame.
We lay out our torch tips, 1-6, take out the allen screw filter from the base of the torch tip, you will find under this screw a very small disc with an orifice in it, (this is very small do not drop on floor)
Now remove this disc and put #2 disc into #1 tip, put 3 disc into #2 tip, put #4 disc into #3 tip, put #5 disc into #4 tip, put #6 disc into #5 tip.
Now replace the allen screw filters. #6 tip now cannot be used, you have to buy a new one unless you can buy a # 6 orifice from your supplier.
Adjust your regulator to the proper pressure. You will find that when you light your torch now, you will only get a reduced flame.
We find that with the students there is always a rush to get lots of heat and solder fast, they are told to use the reduced flame and take lots of time, this way NO FIRE SCALE.