A backdraft damper for permitting a flow of air in an outflow direction and preventing the flow of air in a backdraft direction, including a frame having a transverse opening allowing the passage of air through the frame; a plurality of blades, each blade extending across the frame and mounted to the frame about a central portion by pivot members, for rotation between an open position in which the blade allows air to flow through the frame and a closed position in which the blade blocks air from flowing through the frame, the plurality of blades including one or more first blades arranged to rotate in a first direction from the closed position to the open position; one or more second blades arranged to rotate in a second direction opposite to the first direction from the closed position to the open position; the backdraft damper further including a linkage between the one or more first blades and the one or more second blades to cause the first and second blades to together rotate between the closed and open positions; and the one or more second blades being more balanced about respective pivot members than the one or more first blades thereby to permit the one or more first blades to bias the entire plurality of blades to the closed position while being movable to the open position by the force of air flowing through the frame in the outflow direction.
A backdraft damper for permitting a flow of air in an outflow direction and preventing the flow of air in a backdraft direction, including a frame having a transverse opening allowing the passage of air through the frame; a plurality of blades, each blade extending across the frame and mounted to the frame about a central portion by pivot members, for rotation between an open position in which the blade allows air to flow through the frame and a closed position in which the blade blocks air from flowing through the frame, the plurality of blades including one or more first blades arranged to rotate in a first direction from the closed position to the open position; one or more second blades arranged to rotate in a second direction opposite to the first direction from the closed position to the open position; the backdraft damper further including a linkage between the one or more first blades and the one or more second blades to cause the first and second blades to together rotate between the closed and open positions; and the one or more second blades being more balanced about respective pivot members than the one or more first blades thereby to permit the one or more first blades to bias the entire plurality of blades to the closed position while being movable to the open position by the force of air flowing through the frame in the outflow direction.
A backdraft damper for permitting a flow of air in an outflow direction and preventing the flow of air in a backdraft direction, including a frame having a transverse opening allowing the passage of air through the frame; a plurality of blades, each blade extending across the frame and mounted to the frame about a central portion by pivot members, for rotation between an open position in which the blade allows air to flow through the frame and a closed position in which the blade blocks air from flowing through the frame, the plurality of blades including one or more first blades arranged to rotate in a first direction from the closed position to the open position; one or more second blades arranged to rotate in a second direction opposite to the first direction from the closed position to the open position; the backdraft damper further including a linkage between the one or more first blades and the one or more second blades to cause the first and second blades to together rotate between the closed and open positions; and the one or more second blades being more balanced about respective pivot members than the one or more first blades thereby to permit the one or more first blades to bias the entire plurality of blades to the closed position while being movable to the open position by the force of air flowing through the frame in the outflow direction.
A backdraft damper can include at least one blade rotation about a pivot axis of the pivot pin between an open position and a closed position. The blade may include a leading portion having a lead planar section that is offset on a first side of a pivot axis and a trailing portion having a trailing planar section offset on a second side of the pivot axis, and a seal for sealing against either the leading portion of an adjacent blade or a blade stop. The blade may include a counterweight that such that the blade is biased to the closed position by gravity and is movable to the open position by the force of air flowing through the frame in the outflow direction.
F24F 13/15 - Organes de réglage de l'écoulement d'air, p.ex. persiennes, grilles, volets ou plaques directrices mobiles, p.ex. registres à éléments basculants, p.ex. persiennes à lamelles parallèles basculables simultanément
F16K 1/12 - Soupapes ou clapets, c. à d. dispositifs obturateurs dont l'élément de fermeture possède au moins une composante du mouvement d'ouverture ou de fermeture perpendiculaire à la surface d'obturation à corps de soupape profilé autour duquel le fluide s'écoule quand la soupape est ouverte
F16K 1/22 - Soupapes ou clapets, c. à d. dispositifs obturateurs dont l'élément de fermeture possède au moins une composante du mouvement d'ouverture ou de fermeture perpendiculaire à la surface d'obturation à éléments de fermeture articulés à pivot comportant disque ou volet pivotant dont l'axe de rotation traverse le corps de soupape, p.ex. régulateurs à papillon
A damper comprises a generally rectangular frame extending between opposed open faces and defining an airflow region. One or more damper blades comprises a substantially air-impermeable vane pivotally mounted between the sides of the frame and pivotable between an open position and a closed position. In the closed position an edge of the adjacent blade abuts a blade stop surface formed along each end, such that in the closed position one edge of the blade adjacent to each end of the frame extends into a recess and abuts the blade stop surface, to prevent air from flowing between the blade and the end of the frame. In the preferred embodiments the blade stop surfaces are integrally formed in each end panel.
A damper comprises a generally rectangular frame extending between opposed open faces and defining an airflow region. One or more damper blades comprises a substantially air-impermeable vane pivotally mounted between the sides of the frame and pivotable between an open position and a closed position. In the closed position an edge of the adjacent blade abuts a blade stop surface formed along each end, such that in the closed position one edge of the blade adjacent to each end of the frame extends into a recess and abuts the blade stop surface, to prevent air from flowing between the blade and the end of the frame. In the preferred embodiments the blade stop surfaces are integrally formed in each end panel.
