Question: is mapp gas lighter than air?
Answer: The following figures compare the relative vapor density of fuel gases with that of air: Natural Gas 0.55 LIGHTER than Air Acetylene 0.91 Air 1.00 Propylene 1.42 MAPP* 1.48 HEAVIER than Air Propane 1.56 Butane 2.05 It is important to note that acetylene and natural gas being lighter than air will rise in air.