Patent ID: 8897009
Filing Date: 2014-11-25
Classification: H05K

Abstract:
1. A fan system for an electrical equipment enclosure, said fan system comprising: a housing defining a chamber; a first outlet in communication with said chamber and defined by an opening in a first wall of said housing; a first backflow prevention damper associated with said first outlet, said first backflow prevention damper comprising: (i) a first damper plate movable relative to said housing between a closed position where it is positioned in covering relation with said first outlet and an opened position where it is moved away from said first outlet to allow exhaust air flow through said first outlet from said chamber; and, (ii) a first counterweight connected to said first damper plate that exerts a closing force on said first damper plate that urges said first damper plate toward its closed position, wherein said first counterweight is connected to first damper plate at a location spaced from an inside face of said first damper plate that is oriented toward said chamber when said first damper plate is located in its closed position; wherein said first damper plate selectively pivots about a first pivot axis from its closed position toward its opened position against the closing force of the first counterweight in response to exhaust air flow pressure exerted on the first damper plate by exhaust air flowing from said chamber through said first outlet; said first counterweight comprising a first ballast connected to said first damper plate and located below said first pivot axis when said first damper plate is located in its closed position.