this invention relates to apparatus and methods for use in sealing a vascular puncture site and to apparatus and methods for properly locating and deploying a sealing device . the locating apparatus includes a lumen which extends from an opening in the distal region of the apparatus but located proximally of the sealing device , which lumen extends to another opening in the proximal region of the device . when the distal opening is in communication with blood in a blood vessel , blood flow through the lumen and out of the proximal opening signifies such location to the user . when the sealing device is withdrawn such that the sealing device is deployed such that it blocks the blood flow into the distal port , the user will know the location of the sealing device . in a preferred embodiment , the sealing device is then withdrawn proximally a predetermined distance to assure that no part of the sealing device extends into the blood vessel lumen . the sealing device is then detached from the delivery device .