All gases that are lighter than the surrounding air can be used as a lifting gas for balloons. If air is assigned a density of 1, the relative density of the lifting gas must me less than 1. Lifting gases include:
There are several gases that are used by gas balloonist. The top three gases in the USA are Hydrogen, Helium and Ammonia.
Advantages: Lowest density of all gases, cheap, commonly available.
Disadvantage: Flammable, Explosive when mixed with air.
Advantages: Non-flammable. Lower loss through diffusion than Hydrogen.
Disadvantages: Non renewable, Rare and expensive
Advantages: None. It is used a base value for balloon records.
Disadvantage: Flammable, explosive, poisonous, Not readily available in some parts of the world due to better manufacturing processes.
Advantages: Low cost, readily available.
Disadvantage: only ½ the lifting capability of Hydrogen or Helium, Poisonous to Humans, Caustic, Explosive, Water soluble.