What is a key difference between a check valve and a non-return valve?

In the context of fluid dynamics and valve technology, the distinction highlighted by the correct choice lies in the functionality and application of the non-return valve. A non-return valve is designed to allow the flow in one direction while preventing backflow, but it includes additional features that help mitigate issues such as valve chattering. Chattering typically occurs when the flow conditions are unstable, leading to rapid on-and-off action of the valve. By providing cushioning, a non-return valve can absorb shocks from sudden changes in flow, resulting in a smoother operation and reducing the risk of mechanical wear.

The other options do not accurately reflect the fundamental differences between the two types of valves. For instance, saying that a check valve prevents backflow entirely is not entirely accurate, as check valves can allow minimal reverse flow under certain conditions. The assertion that a check valve is only used in high-pressure systems is misleading, as they can be found in various applications regardless of pressure. Lastly, asserting that a non-return valve is less expensive than a check valve does not provide a clear understanding of the operational distinctions; the price can vary widely based on material, design, and purpose rather than just classification.