A device for sealing an opening or puncture in the wall of a blood vessel or other percutaneous openings. The device includes a shaft section member of a small diameter, with an expandable balloon and atraumatic tip at its distal end. The proximal end of the device has an inflation/deflation port which is utilized to inflate the balloon once it is in place within the blood vessel or other body cavity. The entire device is placed through a hemostasis vascular introducer or sheath, which is used during invasive percutaneous vascular procedures. The balloon is inflated and withdrawn until it engages the inner surface of the blood vessel. A procoagulant is injected via the introducer to the puncture. After a predetermined time period, the balloon is deflated and the device is withdrawn.