Nov71:
O2 escaping at high pressure even from a slow leak, can create high temps (adiabatic )
Wrong way round, surely. You take the gas at high pressure and let it expand rapidly and it gets cold, standard refrigeration technique. You'd only get heat if there was ignition, and no one has mentioned any sign of that so far.
Oh, and keep up the good work, those providing photos, diagrams and explanations of systems, it's very educational.