Abstract: A dispensing device comprising pump for dispensing liquid, the pump comprising a hollow piston moveable within a cylinder, and a valve, controlling the supply of liquid to the piston/cylinder. During a first phase of operation the piston moves outwardly within the cylinder while the valve permits the supply of liquid into the chamber and during a second, subsequent, phase of operation the piston moves inwardly within the cylinder while the valve shuts off the supply of flowable material, with the result that liquid drawn into the chamber during the first phase is pressurized. Arrangements for effective priming and pre-compression of liquid are also described.