Abstract: A metering pump for dispensing a predetermined volume of a liquid or semi-liquid fluid includes a pump body 1, a differential piston 51,52, and a turret 6 secured to a container cap 61. The pump body has a bottom end in communication with the container and a top end 11 capable of being fixed in a desired axial position on the turret. The piston is mounted for fluid-tight sliding in the pump body and has a rest position in which it defines a pump chamber 3, the piston being urged by a return spring 7 towards the turret. The top end 11 of the pump body is axially adjustable within the turret to vary the volume of the pump chamber, and includes integral barb projections 111 that bite into the softer turret material.

Abstract: A device for dispensing of small volume comprises a pump associated with a container of the substance to be dispensed, the pump comprising: a hollow pump body; and a piston sliding inside said pump body in sealing contact with the pump body around a circular periphery of diameter D2; wherein the pump further includes: a push rod including a central channel in which a valve seat is formed, the push rod sliding in contact with the pump body around a circular periphery of diameter D1 less than D2; a punch secured to the piston and capable of bearing in sealed manner against the valve seat; and resilient means urging the piston against the valve seat.