For Sounding Balloons or Red Bull Stratos: Why not use hydrogen over helium

cyberteque:
Just so we know, CodingBadly, how did you loose your eyebrows with hydrogen?

Years ago I worked at a gas compressing plant. One of our products was ultra-pure hydrogen gas. The gas was stored in slender high-strength steel cylinders; a smaller stronger variation of a propane tank. A small thick steel tube was used to transport the gas to each tank.

Despite every precaution, despite using the best materials, an explosion occurred. The explosion had enough energy to open several nearby tanks resulting in an even larger explosion. One of my coworkers was killed.

The investigation revealed that one of the metal fittings corroded. A pinhole leak developed. The escaping gas became hot enough to self-ignite triggering the disaster.