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A backflow preventer for use in a multiple fan array system that draws air from an inlet area and expels it into a discharge area includes a main body defining an open front end and an open rear end and is adapted for attachment to a fan of the fan array system adjacent an inlet of the fan. Doors ar

A backflow preventer for use in a multiple fan array system that draws air from an inlet area and expels it into a discharge area includes a main body defining an open front end and an open rear end and is adapted for attachment to a fan of the fan array system adjacent an inlet of the fan. Doors are 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 and a closed position in which the doors block the open front end and air is prevented from entering through the open front end. The doors are movable between the open position and the closed position by a pressure differential between the inlet area and the discharge area. The doors in the open position form a tapered intake passageway that funnels air into the fan.

대표청구항 ▼

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 exten

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; anddoors 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. 2. The backflow preventer of claim 1, wherein each of the doors comprises a hollow body filled with acoustic insulation. 3. The backflow preventer of claim 1, wherein the doors in the open position form a tapered intake passageway having a wider opening adjacent the open front end and a smaller opening adjacent the open rear end. 4. The backflow preventer of claim 3, wherein a horizontal cross section of each of the doors is generally triangular in shape. 5. The backflow preventer of claim 3, wherein the angle of the tapered intake passageway is in the range of 48 to 52 degrees. 6. The backflow preventer of claim 1, wherein each of the doors is hingedly attached to one of the opposed side walls for pivoting about a vertical axis. 7. The backflow preventer of claim 1, wherein the main body further comprises a central stop extending between the bottom wall and the top wall at a location between the opposed side walls and adjacent the open front end. 8. The backflow preventer of claim 7, wherein each of the doors comprises an extension configured to contact the central stop when each of the doors is in the closed position. 9. The backflow preventer of claim 1, wherein the main body is made of galvanized steel. 10. A multiple fan array system for use in conditioning air in a structure by drawing air from an inlet area and expelling it into a discharge area, the multiple fan array system comprising: at least two fans, each fan having an inlet and an outlet and being operable to draw air in through the inlet and expel air out through the outlet; anda backflow preventer operatively associated with each of the at least two fans, each backflow preventer comprising: a main body defining an open front end and an open rear end; anda pair of 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 be drawn into the fan inlet and a closed position in which air is prevented from entering through the open front end to be drawn into the fan inlet, the attachment of the doors to the main body being configured so that when the main body is mounted on a respective fan, the doors are not biased toward the closed position when the respective fan is off. 11. The multiple fan array system of claim 10, wherein the doors of each backflow preventer are in the open position when all of the at least two fans are operable, and upon one of the at least two fans becoming inoperable the doors of the corresponding backflow preventer are configured to move to the closed position to prevent air from entering through the open front end of the corresponding backflow preventer to be drawn into the inoperable fan. 12. The multiple fan array system of claim 10, wherein each of the backflow preventers includes a flange configured to mount the backflow preventer on a corresponding fan such that the open rear end is adjacent the fan inlet. 13. The multiple fan array system of claim 10, wherein each of the doors comprises a hollow body filled with acoustic insulation. 14. The multiple fan array system of claim 10, wherein the doors of each backflow preventer in the open position form a tapered intake passageway having a wider opening adjacent the open front end and a smaller opening adjacent the open rear end. 15. The multiple fan array system of claim 14, wherein the angle of the tapered intake passageway is in the range of 48 to 52 degrees. 16. The multiple fan array system of claim 15, wherein the tapered intake passageway directs air into the fan inlet, thereby increasing efficiency of the fan by about 3%. 17. The multiple fan array system of claim 14, wherein a horizontal cross section of each of the doors is generally triangular in shape, a side of each of the doors forming a portion of the tapered intake passageway when the doors are in the open position and extending across the open front end when the doors are in the closed position. 18. The multiple fan array system of claim 10, wherein the main body of each of the backflow preventers further comprises a central stop. 19. The multiple fan array system of claim 18, wherein each of the doors comprises an extension configured to contact the central stop when each of the doors is in the closed position. 20. The multiple fan array system of claim 10, wherein each of the doors is hingedly attached to the main body of the backflow preventer for pivoting about a vertical axis. 21. 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; anddoors 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 open position or the closed position.