Fully opening flapper valve apparatus

摘要: An improved flapper valve for installation example, in a tubing string of subterranean well is pivotally movable about horizontal axis into blocking position relative to the vertical fluid flow path string. The circular and formed from tubular segment such manner that, when open position, its concave surface substantially tangentially coincident with projection cylindrical by inside seat, convex prescribes much larger chordal distance containing circle concentric seat than would flat same diameter. Thus, provided wherein given housing diameter, passageway through can be proportionately larger.