What pressure is needed to open a check valve?

The pressure required to open a check valve depends on its design and the specific application, but it generally ranges from a few psi to several hundred psi. Check valves are designed to open when the upstream pressure exceeds the downstream pressure by a certain threshold, known as the cracking pressure. This cracking pressure varies by valve type and manufacturer, so it's essential to consult the specifications for the specific check valve in use.