An oxy-propane torch is lit with just propane, and the flame examined, before oxygen is added, changing the flame character and temperature.
The torch head is gaffed to the table top with enough slack to turn the gas valves. The propane tank and the oxygen tank are on separate dollies. The torch valves are closed, and the tank regulators set so there is about three pounds of pressure behind each gas. (The precise settings of the regulator are a good thing to check out in a practice session before doing this demo.)
With a friction lighter in one hand, open the propane valve on...
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