Patent ID: 8678246
Filing Date: 2014-03-25
Classification: B05C,B65D

Abstract:
1. A piston for insertion in a co-axial cartridge having a tube-like outer wall and a tube-like inner wall defining an annular chamber therebetween, wherein the piston comprises: a cylindrical annular base member which can be inserted into the annular chamber of the cartridge and is displaceable along a cylindrical longitudinal axis in the cartridge, wherein the base member comprises a body and at least one sealing lip protruding from said body so as to extend radially inward farther than said body or any other protrusion from said body, wherein the sealing lip seals against a sealing surface of the tube-like inner wall of the cartridge, the sealing lip extending parallel with or at least at an acute angle to the cylindrical longitudinal axis, wherein a gap is formed between said body and said tube-like inner wall such that the sealing lip is unobstructed and directly accessible through said gap from an end face side of the piston to be raised from the sealing surface by a tool engageable from said end face side of the piston through said gap while closing the cartridge with the piston so that air from the cartridge can escape passing the raised sealing lip and the gap; and a cover plate arranged at the end face of the base member facing a cartridge interior, the cover plate is formed from a material different from that of the base member, wherein the cover plate comprises a sealing element resting against the tube-like inner wall of the cartridge.