Valve

A valve comprising

• a valve housing with a valve inlet, a valve outlet and a passage extending through the valve housing from the valve inlet to the valve outlet,
• a valve seat provided in the passage and comprising a valve sealing surface, and
• a blocking element adapted to be moved at least partly into the valve seat for blocking the passage by abutment on the valve sealing surface, the blocking element being moved along a direction extending under an acute angle to the plane in which the valve seat is arranged,
• wherein
• the valve sealing surface of the valve seat is bulbous in shape and forms a part of the surface of an imaginary annular member,
• the annular member has a bottom face facing the valve inlet and a top face facing the valve outlet, and the valve sealing surface is formed by parts of the surface of the imaginary annular member located in part on the top face and the bottom face, respectively, and, again in part, on the inner surface of the imaginary annular member between the top and the bottom faces thereof,
• the plane in which the valve seat is arranged, extends under an acute angle to the plane in which the annular member is located, and
• the blocking element passes through the valve seat plane and the annular member plane when in abutment on the valve seat surface.