Pump for dosing fluids

A pumping assembly comprising:

• a pump body with a pump bore, and a sleeve fixed axially within the pump bore and having a first end, a second end and a sleeve bore;
• and
• a plunger adapted to enter the first end of the sleeve and which reciprocates within the sleeve bore, such that a pumping chamber is partly defined by a leading face of the plunger and an interior side wall of the sleeve;
• wherein the interior side wall of the sleeve has a first port and a second port which both allow fluid flow through the wall of the sleeve from a feed port into the pumping chamber,
• wherein passage of fluid into the pumping chamber through the first port and the second port is blocked when the plunger advances sufficiently far into the sleeve bore to cover the first port and the second port;
• wherein the first port and the second port are each elongated in a circumferential direction substantially orthogonal to a direction of reciprocation;
• wherein the first port and the second port are each formed as an elongate slot, and wherein respective long edges of each of the elongate slots are substantially parallel to each other;
• and
• wherein the first port and the second port each have a leading edge, wherein the leading edge is the long edge that is closest to the second end of the sleeve;
• and wherein the leading edge of one of the first and second ports is closer to the second end of the sleeve than the leading edge of the other of the first port and the second port.