Non-return Valve Device

A non-return valve device has at least part of a flow channel for a fluid and a movable cord-like sealing element arranged in the flow channel. The sealing element is configured such that it can be moved at least partially between a closed position and an open position, wherein, in the open position, a fluid flow is permitted through the flow channel, whereas in the closed position, the fluid flow through the flow channel is blocked by form-fitting engagement with the sealing element.