US Patent 10473225 Passive valve

A passive in-line valve configured to be actuated without an external control includes a valve housing defining an inlet, an outlet, and a flow path between the inlet and the outlet and a piston housing extending inwardly from the housing. The valve includes a valve piston movably disposed within the piston housing, the valve piston including an upstream side and a downstream side. The valve also includes a control mechanism disposed at least partially within the housing and configured to port outlet static pressure to the upstream cavity in a first state such that pressure is equalized on the valve piston.