Check Valve Basics - Cracking and Resealing Pressures
Cracking pressure is that pressure at which you first get an indication of flow. It's not necessarily when the valve is in the fully open position. When you want to reseal a check valve, you’re looking to get the right resealing pressure in which there’s no indication of flow through the valve—no stream of bubbles. The design of the check valve (poppet and O-ring relationship) and the number of check valves you have in series are factors in the required re-sealing pressure.