Patent ID: 8701943

Claim:
A pump for dispensing fluids comprising: a piston chamber-forming member having a chamber about a chamber axis, the chamber having a chamber wall, an inner end, an open outer end, an outlet and an inlet, a piston-forming element during operation to pump fluid being received in the piston chamber-forming member axially slidable inwardly and outwardly therein between an extended position and a retracted position in cyclical operation of the pump to draw fluid into the chamber via the inlet and dispense fluid via the outlet, the piston-forming element having an inner end and an outer end, the inner end of the piston-forming element located in the chamber with the piston-forming element extending axially in the chamber from the inner end outwardly from the chamber through the open outer end outwardly to the outer end, the piston-forming element having an inner stop flange member on the piston-forming element, the inner stop flange member having an axially outwardly directed stop surface, the piston-forming element having an outer stop flange member on the piston-forming element outwardly from the inner stop flange member, the outer stop flange member having an axially inwardly directed stop surface, the outer stop flange member removably coupled to the piston-forming element by a frangible bridge member, the frangible bridge member being severable to separate the outer stop flange member from the piston-forming element, the piston chamber-forming member having a fixation portion to engage with the outer stop flange member for facilitating fixedly securing of the outer stop flange member to the piston chamber-forming member, wherein with the outer stop flange member coupled to the piston-forming element, in a transfer position the piston-forming element is located in the chamber with the fixation portion engaging the outer stop flange member, wherein in the transfer position the fixation portion and the outer stop flange member are adapted to be fixedly secured together against relative axial movement, wherein in the transfer position after the fixation portion and the outer stop flange member have been fixedly secured together against relative axial movement, the outer end of the piston-forming element is movable relative to the piston chamber-forming member to sever the frangible bridge member thereby separating the outer stop flange member from the piston forming element, wherein after the fixation portion and the outer stop flange member have been fixedly secured together against relative axial movement and the outer stop flange member has been severed from the piston-forming element, the outer stop flange member presenting the axially inwardly directed stop surface axially opposed to the axially outwardly directed stop surface on the inner stop flange member and engagement between the axially inwardly directed stop surface and the axially outwardly directed stop surface prevents sliding of the piston-forming element outwardly in the piston chamber-forming member past the outer stop flange member.