Patent ID: 8900526

Claim:
A device for manually metering liquids comprising a cylinder, and a piston housed inside the cylinder, with the device being arranged so that during a metering operation, the piston moves along an axis of the piston to suck in or to expel a volume of liquid, the device further comprising: a joint housed in the cylinder and arranged so as to provide a sealing between the cylinder and the piston, wherein during a liquid metering operation, the joint remains fixed with respect to a movement of the piston, wherein the joint comprises a first, external part which cooperates with the internal wall surface of the cylinder and which functions to provide sealing of the joint against an internal wall surface of the cylinder, and, a second, internal part, which is in contact with the piston and which functions to provide a sealing of the joint against the piston and to exert a friction force on the piston upon the movement of the piston relative to said joint, wherein said first and second parts are made in one piece of a same elastomer material, wherein said elastomer material is in sealing contact with said piston, wherein said first part is more rigid than said second part, wherein the friction force imparted by the joint pressing against the piston surface upon the movement of the piston with respect to the joint is smaller than or equal to 2 N, and wherein the joint comprises at least two distinct contact surfaces with the piston and is arranged so as to form a closed space between said two contact surfaces and the piston.