Patent ID: 8752582

Claim:
A fluid flow apparatus comprising: a housing having an inlet end and an outlet end; a flow control disposed within the housing; a sequencing mechanism containing viscous fluid for dampening movement of the flow control, the sequencing mechanism configured to sequence the fluid flow apparatus from a current state to a different one of a plurality of states in response to removal and restoration of pressure at the inlet end, the plurality of states including: a first state wherein the sequencing mechanism maintains the flow control in a substantially open position to allow fluid to flow through the apparatus between the inlet and outlet ends of the housing; and a second state wherein the sequencing mechanism maintains the flow control in a substantially closed position to resist fluid flow between the inlet end and the outlet end of the valve housing; wherein the flow control includes undulations configured to provide for expansion and contraction of the flow control in an axial direction, the sequencing mechanism being encircled by at least a portion of the undulations; and wherein the flow control includes a plurality of support rings, each support ring of the plurality of support rings disposed in an undulation of the undulations to reduce the risk that external pressure will cause the undulations to collapse radially.