Valve apparatus for controlling fluid flow through a duct or opening, the valve apparatus comprising: • a valve seat body having a valve seat hole being configured to allow the fluid to flow through it, and • a damper body for closing the valve seat hole, • wherein the valve seat body and the damper body are movable relative to each other between an open configuration and a closed configuration, wherein in the open configuration the fluid may flow through the valve seat hole and in the closed configuration the damper body interacts with the valve seat body in a sealing manner such that the fluid may not flow through the valve seat hole, • wherein the valve seat hole has a hole contour formed by a hole edge and the damper body has a damper contour formed by a damper edge, the hole edge and the damper edge being configured to interact with each other in the sealing manner thereby forming a circumferential sealing line having a circumferential sealing length, and • wherein the hole contour has a plurality of hole protuberances and the damper contour has a plurality of damper protrusions, so that the circumferential sealing length is larger than a reference length being defined by a length of a circumference of an equal area circle having an area equal to an area of the valve seat hole, characterized in that • the valve seat hole has a central region and the hole protuberances extend from opposite sides of the central region, and the damper body has a central portion and the damper protrusions extend from opposite sides of the central portion, and • the hole protuberances on each of the opposite sides of the central region extend parallel to each other and the damper protrusions on each of the opposite sides of the central portion extend parallel to each other. • a valve seat body having a valve seat hole being configured to allow the fluid to flow through it, and • a damper body for closing the valve seat hole, • wherein the valve seat body and the damper body are movable relative to each other between an open configuration and a closed configuration, wherein in the open configuration the fluid may flow through the valve seat hole and in the closed configuration the damper body interacts with the valve seat body in a sealing manner such that the fluid may not flow through the valve seat hole, • wherein the valve seat hole has a hole contour formed by a hole edge and the damper body has a damper contour formed by a damper edge, the hole edge and the damper edge being configured to interact with each other in the sealing manner thereby forming a circumferential sealing line having a circumferential sealing length, and • wherein the hole contour has a plurality of hole protuberances and the damper contour has a plurality of damper protrusions, so that the circumferential sealing length is larger than a reference length being defined by a length of a circumference of an equal area circle having an area equal to an area of the valve seat hole, characterized in that • the valve seat hole has a central region and the hole protuberances extend from opposite sides of the central region, and the damper body has a central portion and the damper protrusions extend from opposite sides of the central portion, and • the hole protuberances on each of the opposite sides of the central region extend parallel to each other and the damper protrusions on each of the opposite sides of the central portion extend parallel to each other.