Gday Pat I have also played with hydrogen, a 2 litre coke bottle full actually, and to me and my work mates it was like a bomb, the blast wave was incredible and the flying bottle set fire to our rag bag, lucky
the boss was away LOL.
We first started by igniting the hydrogen by running a small hose into our metal quenching bath
and igniting the bubbles as they popped... And they were like a large crackers.
So if you try this do be very careful . Cheers Dave