The manufacturer was approached by American Electric Power in 2002 regarding an interest in supplying them a heavy duty inflatable device to temporarily seal off an 18' wide x 20' high duct work in a large coal fired power plant.
Units that share a common stack often experience opacity excursions that are aerosols rather than particulates. These aerosols form when the stack flue gas temperature falls below the dew point temperature because of air in-leakage from out of service units, especially at reduced loads. Although zero leakage dampers are available, most units are not equipped with this type of damper. The plant personnel or their designated contractor will sometimes install barriers made of wood and plastic sheeting in order to effectively seal off this air in-leakage from the existing dampers. These temporary wood frame & plastic barriers are time and labor intensive to make, install and remove. These temporary barriers are usually discarded at the end of the outage.
The device is called a "duct balloon" which can be inserted upstream of a louvered damper and inflated to provide a temporary barrier inside the duct. The balloon is constructed out of a durable, acid resistant fabric, and can be reused outage after outage. The material is strong, lightweight, resistant to tears, and is rated to 485°F. Using the supplied 110V blower system, they inflate in 10 minutes or less. The balloon can be quickly deflated by opening a large zipper and it can collapses down small enough to fit through an existing man way allowing it to be removed from the duct work in minutes.
Past applications for using duct balloons are: