A oxygen concentrating system comprising an adsorption column having a first end and a second end, a shell enclosing the column and defining a product gas storage space between the column and the shell, a product conduit connecting the product gas storage space to a product output point, a first conduit comprising at least one first valve having at least a first and second configuration, in the first configuration, compressed air flows from the feed point to the first end, and, in the second configuration, waste gas flows from the first end to the waste point, and a second conduit comprising at least one second valve having at least a first and second configuration, in the first configuration, the product gas flows from the product gas storage space to the second end, and, in the second configuration, the product gas flows from the second end to the storage space.