Not so. We run high purity hydrogen in our generators to cool the rotors of the generators. Upper explosive limit is 59%.
Upper explosive limit is 59%.
75%
https://www.mathesongas.com/pdfs/products/Lower-%28LEL%29-&-Upper-%28UEL%29-Explosive-Limits-.pdf
http://www.engineeringtoolbox.com/explosive-concentration-limits-d_423.html