A shaft furnace bleeder valve for controlling a gas outflow from the interior of a pressurized furnace to the ambient atmosphere through an exhaust conduit is proposed. The bleeder valve comprises a valve seat associated with the exhaust conduit, a movable closure member having a central closure surface and a peripheral sealing surface cooperating with the valve seat, the closure surface comprising a convex surface at least in proximity to the sealing surface. The valve further has an actuating mechanism, which is connected to the closure member for moving the closure member between a closed position on the valve seat and an open position distant from the valve seat. According to the invention, the closure member comprises a recurved deflection portion at the periphery of the peripheral sealing surface, the recurved deflection portion comprising a deflection surface inclined against the convex surface by an angle in the range of 30° to 70° for imparting to a gas outflow passing between the valve seat and the closure member a velocity component which is opposite to the initial opening movement of the closure member.