2. There is a saturated bond between carbon and carbon in propane molecule. It is chemically more stable than acetylene, and safer than acetylene in use. Although much safer, propane is a flammable gas after all. It is prone to accidents such as fire.
3. Although the temperature of the oxygen-propane flame is not as high as that of the oxygen-acetylene flame, the flame is softer and the volumetric calorific value is larger than that of acetylene. (The total calorific value is higher than that of acetylene, but the combustion heat per gram is lower than that of acetylene, the flame temperature is lower, and the flame heat is more dispersed)