Valve and method for manufacturing a closure member

An eccentric butterfly valve comprising:

• a closure member;
• a valve body surrounding the closing member;
• a balancing disk;
• a sealing surface extending along an outer periphery of the closure member to form a sealing plane;
• a drive shaft having a center axis and a first end protruding out of the eccentric butterfly valve;
• and
• a first opening and a second opening, the first opening being located on the same side of the sealing plane as the drive shaft when the closure member is in a fully closed position, in which the sealing surface contacts a mating surface on the valve body, wherein:
• the closure member engages the drive shaft and is rotatably arranged in the eccentric butterfly valve to be moved by rotation around the center axis of the drive shaft between the fully closed position, in which the closure member prevents flow through the eccentric butterfly valve, and a fully open position, in which the closure member does not prevent flow through the eccentric butterfly valve;
• the closure member has a first face facing towards the first opening in the fully closed position, a second face facing towards the second opening in the fully closed position;
• the center axis is offset by a distance from a center line of a flow channel through the eccentric butterfly valve;
• the closure member is provided with a balancing disk extending from the first face in a direction away from the sealing plane to form an angle with the sealing plane which is 30° to 60°;
• the balancing disk is perforated by a plurality of through holes;
• the balancing disk is formed as an integral part of the closure member;
• the first opening is an inlet and the second opening is an outlet;
• and
• the balancing disk extends from the first face at a leading edge side of the closure member which moves towards the second opening when the closure member is moved from the fully closed position towards the fully open position.