A gas concentrator system, comprising: a gas compressor configured to receive and compress ambient air to provide a supply of pressurized gas mixture; at least two gas separation sieve beds configured to adsorb at least one gas species from the pressurized gas mixture from the compressor so as to provide an enriched gas product, wherein the gas separation sieve beds are configured to cycle between periods of pressurizing and venting; first and second valves configured to be independently operable to regulate flow of the pressurized gas mixture to the sieve beds; a fluid line coupled to the gas separation sieve beds, the fluid line configured to provide the enriched gas product toward an outlet; characterized in that the gas concentrator system further comprises: at least two sensors coupled to the fluid line, wherein the at least two sensors are at least two of: (a) a flow rate sensor configured to measure a flow rate of the enriched gas product through the fluid line; (b) a temperature sensor coupled to the fluid line and configured to measure ambient temperature; and (c) a pressure sensor coupled to the fluid line and configured to measure ambient pressure; a controller configured to selectively control the first and second valves to control either of the periods of pressurizing and venting of the sieve beds based on at least two of the measured flow rate, ambient temperature, and ambient pressure; and a motor speed controller operatively connected to the controller and the gas compressor and wherein the controller is configured to control an output of the compressor via the motor speed controller based on inputs from the flow rate sensor, the temperature sensor and the pressure sensor. a gas compressor configured to receive and compress ambient air to provide a supply of pressurized gas mixture; at least two gas separation sieve beds configured to adsorb at least one gas species from the pressurized gas mixture from the compressor so as to provide an enriched gas product, wherein the gas separation sieve beds are configured to cycle between periods of pressurizing and venting; first and second valves configured to be independently operable to regulate flow of the pressurized gas mixture to the sieve beds; a fluid line coupled to the gas separation sieve beds, the fluid line configured to provide the enriched gas product toward an outlet; at least two sensors coupled to the fluid line, wherein the at least two sensors are at least two of: (a) a flow rate sensor configured to measure a flow rate of the enriched gas product through the fluid line; (b) a temperature sensor coupled to the fluid line and configured to measure ambient temperature; and (c) a pressure sensor coupled to the fluid line and configured to measure ambient pressure; (a) a flow rate sensor configured to measure a flow rate of the enriched gas product through the fluid line; (b) a temperature sensor coupled to the fluid line and configured to measure ambient temperature; and (c) a pressure sensor coupled to the fluid line and configured to measure ambient pressure; a controller configured to selectively control the first and second valves to control either of the periods of pressurizing and venting of the sieve beds based on at least two of the measured flow rate, ambient temperature, and ambient pressure; and a motor speed controller operatively connected to the controller and the gas compressor and wherein the controller is configured to control an output of the compressor via the motor speed controller based on inputs from the flow rate sensor, the temperature sensor and the pressure sensor.