These valves do not prevent the regurgitation of the blood, or the passage of injection from below upward.

The valves prevent backflow in the now-tortuous route through the cavernosa.

Consider installing "check valves" to prevent flood water from backing up into the drains of your home.

The valve prevents the waste from flowing backward.

These valves prevent blood from flowing back into the ventricles.

A one-way valve in the tubing prevents water from siphoning back into the reservoir.

Note that the anti-siphon valve in medical shunts is preventing excess forward flow of liquid.

In plumbing systems, the anti-siphon valve is preventing backflow.

Importantly, this valve, in its new capacity, will now effectively prevent the escape of urine from the stoma.

This valve prevents exhaust gasses entering the secondary turbine.