Patent ID: 8256464

Claim:
A vacuum backflow prevention system, comprising: a fluid ejector tube adapted for insertion into a patient's mouth; a backflow prevention device, comprising: a distal portion defining a valve seat portion and an inlet, the distal portion operably connected to the fluid ejector tube; a proximal portion defining an outlet, the proximal portion configured for operative connection to the distal portion; a valve member retained between the proximal and distal portions at a single location along a peripheral edge of the valve member, the valve member being moveable from a first position substantially blocking fluid flow between the inlet and the outlet, and a second position wherein at least a portion of the valve member is moved in a direction toward the outlet to permit fluid to flow from the inlet to the outlet under a vacuum condition, the valve member having a stiffening structure extending from a surface of the valve member that faces the outlet on a portion of the valve member that is moved toward the outlet in the second position, the stiffening structure providing increased resistance to movement of the at least a portion of the valve flap from the first position to the second position; wherein the stiffening structure extends around a circumference of the valve member to provide an increased thickness of the valve member around the circumference.