The bladder valve uses parallel, expandable airfoils mounted in an arrangement that when expanded reduces the available airflow area. This reduction in airflow area decreases airflow. The advantage of this arrangement is that the pressure drop required to reduce airflow is significantly less than butterfly, shutter or rotary valves. Direction of airflow is never changed, so there is little or no turbulence caused by the valve. Because there are no flat surfaces on which the air must impinge, there is virtually no dirt buildup in the valve, which eliminates the need for periodic cleaning. There are also no mechanical linkages or adjustments.