A pump including: - a stator (4), - a rotor (6) slidably and rotatably mounted at least partially in the stator, the rotor comprising a first axial extension (24) having a first diameter (D1 ) and a second axial extension (26) having a second diameter (D2) greater than the first diameter, - a first valve (V1 ) formed by a first valve seal (18) mounted on the stator around the first axial extension, in conjunction with a first channel (42) in the rotor that is configured to allow liquid communication across the first valve seal when the first valve is in an open position, - a second valve (V2) formed by a second valve seal (20) mounted on the stator around the second axial extension, in conjunction with a second channel (44) in the rotor that is configured to allow liquid communication across the second valve seal when the second valve is in an open position, and - a pump chamber (8) formed between the rotor and stator and between the first valve seal and second valve seal. The pump further comprises a priming actuator (30) mounted on a housing of the stator and movable from a locked operating position to a priming position, the priming actuator (30) configured to engage and axially displace the rotor from an operating position in which at least one of the first and second valves is closed, to a priming position in which both first and second valves are open.
