This element functions either as a check valve that closes instantaneously and remains closed when reverse flow occurs, or as a positive-acting leaf valve closing linearly over the prescribed time. An ideal valve useful for verifying best-case assumptions or representing motorized valves.

The head loss/discharge coefficient accounts for the vena contracta by means of a formula for two-dimensional flow solved with the Schwartz-Christoffel transformation.

If the check valve closes, it remains shut independent of the pressure difference across it. When the valve is closed, independent vapor pockets can exist on both sides of the valve.