ARD: Fixed Pressure Relief Duct Access Door

KEES negative pressure relief access doors allow fire dampers to be inspected and reset while protecting the duct from damage. Installed in positive pressure ducts on the downstream side of the fire dampers, these doors open inward to prevent the duct from collapsing under excessive negative pressure. Under positive pressure, doors will automatically close. Doors must be installed vertically to properly relieve 1 to 1.5" w.g. negative pressure (pressure not adjustable).