A humidifier apparatus for operating at an air pressure is disclosed for use with a respiratory therapy breathing apparatus that provides a breathable gas supply to patients requiring higher concentrations of liquid vapor and gas pressure. Additionally, a client-side override of the load order of the plurality of components may be conducted based on the usage pattern. , nitrogen from air, to produce an oxygen-enriched gas stream using a multi-port indexing drum valve, a system comprising a multi-port indexing drum valve and method for operating such a system.