A method of providing oxygen enriched gas to a user of an oxygen concentrator, the oxygen concentrator comprising: at least two canisters (302, 304); gas separation adsorbent disposed in the at least two canisters, wherein the gas separation adsorbent separates at least some nitrogen from air in the canister to produce oxygen enriched gas; and a compression system comprising at least one compressor coupled to the at least two canisters; a controller that monitors the pressure of the at least two canisters when the canisters are not being used; characterized in that the method comprises: the controller automatically determining if the oxygen concentrator is in an off state; the controller automatically determining a pressure of the canisters, wherein the pressure is determined when the oxygen concentrator is in an off state, wherein the controller starts the compression system when the determined pressure in at least one of the canisters drops below a specified pressure; the controller operating the compressor at a compressor speed sufficient to pressurize the canisters to a desired pressure based on the determined pressure of the canister when the oxygen concentrator is in an off state, wherein operating the compressor pressurizes the canisters with compressed air that is passed through an adsorbent that dries the water from the air prior to the air entering the at least one canisters; further comprising continually monitoring the pressure of at least one of the canisters with the controller when the oxygen concentration is in an off state. at least two canisters (302, 304); gas separation adsorbent disposed in the at least two canisters, wherein the gas separation adsorbent separates at least some nitrogen from air in the canister to produce oxygen enriched gas; and a compression system comprising at least one compressor coupled to the at least two canisters; a controller that monitors the pressure of the at least two canisters when the canisters are not being used; characterized in that the method comprises: the controller automatically determining if the oxygen concentrator is in an off state; the controller automatically determining a pressure of the canisters, wherein the pressure is determined when the oxygen concentrator is in an off state, wherein the controller starts the compression system when the determined pressure in at least one of the canisters drops below a specified pressure; the controller operating the compressor at a compressor speed sufficient to pressurize the canisters to a desired pressure based on the determined pressure of the canister when the oxygen concentrator is in an off state, wherein operating the compressor pressurizes the canisters with compressed air that is passed through an adsorbent that dries the water from the air prior to the air entering the at least one canisters; further comprising continually monitoring the pressure of at least one of the canisters with the controller when the oxygen concentration is in an off state. the controller automatically determining if the oxygen concentrator is in an off state; the controller automatically determining a pressure of the canisters, wherein the pressure is determined when the oxygen concentrator is in an off state, wherein the controller starts the compression system when the determined pressure in at least one of the canisters drops below a specified pressure; the controller operating the compressor at a compressor speed sufficient to pressurize the canisters to a desired pressure based on the determined pressure of the canister when the oxygen concentrator is in an off state, wherein operating the compressor pressurizes the canisters with compressed air that is passed through an adsorbent that dries the water from the air prior to the air entering the at least one canisters; further comprising continually monitoring the pressure of at least one of the canisters with the controller when the oxygen concentration is in an off state.