Patent ID: 7604618

Claim:
A syringe comprising: a plunger comprising a seal member disposed within a seal seat and adjacent a collar, wherein the seal seat comprises a circumferential groove; and a chamber for receiving the plunger, where the plunger is axially movable with respect to the chamber, the seal member is operable to sealingly engage an inside surface of the chamber but move along the inside surface during an actuation of the plunger, and the circumferential groove has a geometry extending across a bottom surface that provides for escape of air from the chamber across the bottom surface between the seal member and the circumferential groove during actuation of the plunger against air in the chamber, and where the seal member is responsive to seal against the collar during actuation of the plunger against a viscous material in the chamber, thereby forming a seal against escape of the viscous material past the seal member.