Abstract: Web drying equipment, including a dryer through which a web passes, web drying nozzles within the dryer for directing heated air against the web, air supply header means in the dryer and in air delivering communication with the nozzles which discharge heated air toward the web for supporting and drying the web, an exhaust air duct extending from the interior of the dryer for conveying spent air therefrom. An exhaust flow rate control system is provided for controlling the rate of flow of the spent air from the dryer including (1) a valve in the exhaust duct for varying the rate of air flow from the dryer, (2) a controller for operating the valve, (3) a sensor located in the exhaust duct for measuring air pressure therein and for sending a corresponding signal to the controller, (4) a speed sensor for measuring the speed of the web passing through the dryer and sending a corresponding signal to the controller.