Originally Posted by Boatyarddog
Don't rely on the check valve in the OVB hand type pumps, to keep your tank from back filling.
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SV Cloud Duster
What is an OVB hand type pump
All of the hand bilge
type pumps I'm aware of have an inlet and an outlet valve--two check valves in series to prevent backflow. If one of the valves fails, the pump
won't pump (meaning it is likely to get fixed), but it still won't backflow.