Abstract: The present invention relates to a check valve, and to a device having a check valve, and to a method of cleaning a check valve. In order to provide a check valve or a device having a check valve or a method of cleaning a check valve, in which sufficient cleaning of the non-flow-facing regions of the valve closing body is also ensured, it is proposed according to the invention that an element reducing the flow cross-section is provided in a region of the opening stop in addition to the opening stop so that, when the valve closing body is in the open position and the fluid flows through the check valve counter to the blocking direction, a non-flow-facing region of the surface of the valve closing body has at least an average wall shear stress of 50% compared to an average wall shear stress of a flow-facing region of the surface of the valve closing body.