[Ian Robinson]

I've worked with gases as a chemist and then later as an engineer and am well aware of the risks involved with high pressure gases.

Not something to mess with unless you are properly trained and have the right gear.

I am reluctant to handle high pressure H2 gas , it's too easy when venting and mixing gases for static eletricity or a spark to cause ignition to happen (we had strick gas regulation and continuously monitored H2 concentration when I was using the gas mixing station, and when involved in gas plant. The reason for mixing H2 with N2 is to reduce the possibility of an inadvertent ignition. I used to know the LEL and UEL for H2 in N2 (or air) and this info is readily accessible in any good combuston engineering handbook.

The gas needs to be dried too , one of the main reasons for hypersensitisation is removal of moisture from the emulsion , moist forming gas mixture will result in poor hypersensitisation.