Manually operated pump

A manually operated pump (1), comprising

• a cup-shaped body (2) inside which a piston (3) associated with a hollow stem (4) for its movement in the cup-shaped body (2) sealingly slides,
• the manually operated pump (1) having a base (5), which closes the cup-shaped body (2), the base (5) having a hole (11) for the stem (4),
• the stem (4) and the base (5) being torsionally coupled,
• at least part of the cup shaped-body (2) and of the piston (3) defining a compression chamber (6) associated with at least one suction valve element (8) and a delivery valve element (9),
• the delivery valve element (9) being in communication with a cavity (4A) of the stem (4),
• a dispensing button (10) being sealingly fitted on the stem (4), the dispensing button (10) and the stem (4) being mutually constrained so that the dispensing button (10) limitedly rotates with respect to an axis (A) of the stem (4) between a first dispensing position and a second closing position in which at least one tooth (D) of the dispensing button (10) stops against a surface (13) of a ring nut (12) so as to prevent a stroke of the stem (4),
• the manually operated pump (1) being characterized in that the ring nut (12) is configured to be coupled torsionally to the base (5) or to the cup-shaped body (2) in at least two alternative mounting positions, such that,
• if the ring nut (12) is in its first mounting position and the dispensing button (10) is in the dispensing position, a first groove (S1) of the ring nut (12) faces the tooth (D) which can slide in it up to a first stop (F1), allowing a first stroke of the stem (4) and that,
• if the ring nut (12) is in its second mounting position and the dispensing button (10) is in the dispensing position, a second groove (S2) of the ring nut (12) faces the tooth (D) which can slide in it up to a second stop (F2), allowing a second stroke of the stem (4) different from the first stroke of the stem (4), so that, during the assembly of the manually operated pump (1) the positioning of the ring nut (12) in the first or second mounting position determines a first or a second delivery volume of the manually operated pump (1).