Each fuel gas has a different ratio of carbon atoms to hydrogen atoms and this means that different amounts of oxygen are needed to burn the fuel gas efficiently. This ratio of fuel to oxidant affects the temperature of the flame, the flammability and explosive limits.
- Acetylene is lighter than air and gives the highest flame temperature of all fuel gases. It also uses the least amount of oxygen to give complete combustion
- Hydrogen is lighter than air and burns with an invisible flame. It is also the only fuel gas that does not contain any carbon atoms
- Propane is heavier than air, having both a high primary and secondary flame temperature
- Liquid Petroleum Gas (LPG) is a by-product of crude oil refinement. It is made up of several fuel gases such as methane, butane and propane. The ratios of the gases vary between suppliers and for this reason flame properties can also differ.