Many fire departments now use HP composit cylinders. An exploding composit cylinder won't have as much energy in the form of flying steel or aluminum which is heavy compared to composit material so these type cabinets may work fairly well. The ideal containment would be an inground water filled pit that would direct the energy straight up. More people get killed or injured by exploding tires during mounting than exploding scuba cylinders.
I have pictures of a fire truck that was very very heavily damaged from an SCBA blowing up. There is still a massive amount of energy released when they let go.