Sealing device

An apparatus for sealing a wide variety of vessels and for providing access to the interior of such vessels while sealed. In some embodiments, a sealing apparatus includes a base plate, a cover plate, and a seal that is disposed therebetween. In use on a vessel, when the seal is disposed in a rest position, it covers a vessel-access hole that penetrates the base plate and communicates with the underlying vessel. To temporarily displace the seal, a tube, such as a syringe needle, etc., is inserted through a guide hole in the cover plate. The tube contacts the seal, which forces the seal to move at least partially out of its sealing position. With continued downward movement, the tube enters the underlying vessel so that it can withdraw or add fluid to it. When the tube is withdrawn, the seal returns to its sealing position.