Flow-Tek make Single Acting Altitude Control Valve closes at a preset maximum water level to prevent overflow of a ground storage tank or reservoir and opens to refill when the water level in the tank or reservoir lowers. This type of Altitude Control Valve should be used when the supply pressure is appreciably higher (15 psi+) than the head developed by a full ground storage tank or reservoir.

An altitude control valve controls the level of a tank. The altitude valve will remain open while the tank is not full and it will close when the tanks reaches its maximum level. The opening and closing of the valve requires no external power source (electric, pneumatic, or man power), it is done automatically, hence its name.