Patent ID: 9605868
Date: 2017-03-28
CPC Classifications: F24F

Claim:
1. A backflow preventer for use in an air handling system including at least one fan having an inlet and an outlet for drawing air from an inlet area and expelling air into a discharge area, the backflow preventer comprising: a main body having a top wall, a bottom wall, and opposed side walls extending between the top and bottom walls, the main body defining an open front end and an open rear end and adapted for attachment to the fan of the air handling system adjacent the inlet of the fan such that air flowing into the fan inlet must first pass through the main body; and doors attached to the main body and configured for movement between an open position in which air is permitted to enter through the open front end to flow toward the open rear end and a closed position in which the doors block the open front end and air is prevented from entering through the open front end to flow toward the open rear end, the doors being movable between the open position and the closed position by a pressure differential between the inlet area and the discharge area, the attachment of the doors to the main body being configured so that when the main body is mounted on the at least one fan, the doors are not biased toward the closed position when the fan is off.