Hydrogen Line Wikipedia

Hydrogen - Wikipedia.

Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula H 2.It is colorless, odorless, tasteless, non-toxic, and highly combustible.Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter..

https://en.wikipedia.org/wiki/Hydrogen.

Hydrogen safety - Wikipedia.

Inerting chambers and/or purging gas lines is an important, standard safety procedure to take when transferring hydrogen. In order to properly inert and/or purge, the flammability limits must be taken into account, and hydrogen's are very different from other kinds of gases. At normal atmospheric pressure it is 4% to 75%, based on the volume percent of hydrogen in oxygen ....

https://en.wikipedia.org/wiki/Hydrogen_safety.