I didn't know this, here's the relative temps:

Pure oxygen, instead of air (20% oxygen/80% nitrogen), is used to increase the flame temperature to allow localized melting of the workpiece material (e.g. steel) in a room environment. A common propane/air flame burns at about 3,630 °F (2,000 °C), a propane/oxygen flame burns at about 4,530 °F (2,500 °C), and an acetylene/oxygen flame burns at about 6,330 °F (3,500 °C).

There was a previous discussion on propane use. If anyone has further experience please share the info. Heating time relative to oxy, etc., etc. Santa Barbara Iron and Metal(scrap/recycler) uses only propane for their cutting torches as it saves them a lot of $, according to the owner.

thanks, Brian