I wonder if we couldn't use an oxygen concentrator as a first stage instead of relying on stored oxygen. This would obviously increase the cost of the appliance

I wonder if we couldn't use an oxygen concentrator as a first stage instead of relying on stored oxygen. This would obviously increase the cost of the appliance (probably by a significant amount) but it would be safer and less disruptive (no need for a new distribution mechanism and you can just upgrade existing appliances).