Patent ID: 7284474
Filing Date: 2007-10-23
Classification: A61M,F04B,F16J

Abstract:
1. A piston pumping system comprising a piston guided within a guide tube and capable of performing a stroke movement along its longitudinal axis, opening into a pumping chamber, the pumping chamber being connected via a liquid-conveying connection with valve to a storage vessel and from the pumping chamber a liquid conveying connection leads to a device for delivering the liquid, wherein within the guide tube is formed an O-ring seal held by a groove which seals off the piston, has a gas permeation coefficient of 100 to 500 N*cm 3 *mm/(m 2 *h*bar) for nitrogen (N 2 ) and a radial compression of less than 30% and the seal fills the groove with a groove filling level of more than 90%.