System and methods for concentrating gas

Systems and methods are provided that obtain the same or better level of performance by using lower operating flow rates, pressures and/or optimized flow distributions within the system. This extends the life of system components and lower energy consumption. In one embodiment, gas separation (or sieve) beds that are used to separate gaseous components are provided that have lower flow and pressure requirements compared to conventional beds. The sieve beds include, for example, a diffuser having low solid area in cross-section and maximum open area for flow while providing adequate mechanical properties to contain sieve material and support filter media, In another embodiment, systems and methods are provided having an indicator when a component has been serviced or repaired. This provides an indication whether the component has been tampered with in any manner. This allows the manufacturer to determine if the component was serviced, repaired, or tampered with outside the manufacturer's domain.