A pumping device for processing a liquid, comprising: - a plurality of pistons, each of which is slidable along a movement direction in order to vary volume of a corresponding chamber; - a casing inside of which a driving device is housed for moving each piston of the plurality of pistons along the movement direction; - a head inside of which the chambers are at least partially obtained; - a plurality of suction valves, each one of which is associated with a chamber and is operable for enabling the liquid to enter the chamber; - a plurality of delivery valves, each one of which is associated with a chamber and is operable for enabling the liquid to exit the chamber; wherein each suction valve has an axis arranged transversely to a further axis of the delivery valve associated with the same chamber; the pumping device further comprising an intermediate body interposed between the casing and the head, the intermediate body being distinct from the casing and from the head, sealing means being housed in the intermediate body to prevent leakage of fluid from each chamber towards the casing, the sealing means comprising a first sealing element, the intermediate body being provided with guide means for guiding each piston along the movement direction, characterized in that the guide means comprise, for each piston, a sleeve housed in the intermediate body, the sleeve having a hole in which the piston is slidable, the first sealing element surrounding the piston in a position closer to the chamber and being interposed, in a radial direction, between the piston and the intermediate body, the sealing means housed in the intermediate body further comprising a second sealing element surrounding the piston in a position further away from the chamber. - a plurality of pistons, each of which is slidable along a movement direction in order to vary volume of a corresponding chamber; - a casing inside of which a driving device is housed for moving each piston of the plurality of pistons along the movement direction; - a head inside of which the chambers are at least partially obtained; - a plurality of suction valves, each one of which is associated with a chamber and is operable for enabling the liquid to enter the chamber; - a plurality of delivery valves, each one of which is associated with a chamber and is operable for enabling the liquid to exit the chamber; wherein each suction valve has an axis arranged transversely to a further axis of the delivery valve associated with the same chamber; the pumping device further comprising an intermediate body interposed between the casing and the head, the intermediate body being distinct from the casing and from the head, sealing means being housed in the intermediate body to prevent leakage of fluid from each chamber towards the casing, the sealing means comprising a first sealing element, the intermediate body being provided with guide means for guiding each piston along the movement direction, characterized in that the guide means comprise, for each piston, a sleeve housed in the intermediate body, the sleeve having a hole in which the piston is slidable, the first sealing element surrounding the piston in a position closer to the chamber and being interposed, in a radial direction, between the piston and the intermediate body, the sealing means housed in the intermediate body further comprising a second sealing element surrounding the piston in a position further away from the chamber.