Adjustable device for distributing liquid samples

An adjustable device for distributing liquid samples, comprising, in combination:

• a casing incorporating a mechanism for adjusting the volume of liquid samples to be distributed, a volume indicator unit coupled with said mechanism;
• a lower tip member terminating in a tapering end, said casing including a lateral supply tube, provided with a first non-return valve and means for allowing tight holding of a reservoir containing said liquid sample to be distributed;
• a measuring chamber arranged in said tip member for receiving, with a slight clearance, a calibrated piston reciprocally mounted in said chamber and in the lower part of the casing, said piston being elastically urged upwardly, the upper end of said piston cooperates with a stop for limiting upward stroke, said piston being adjustable in position by means of said adjusting mechanism, said chamber communicating near its upper end with an outside medium with the interposition of a second non-return valve;
• a control shaft including a push button at the upper end thereof and the lower end of said control shaft cooperates with said upper end of the piston, said shaft including retaining means for preventing upward escape of said shaft;
• and
• means for ensuring the tight holding of the measuring chamber, near its upper end and above the inlet of said lateral supply tube, said mechanism for adjusting the volume of liquid samples comprises a hollow, externally threaded shaft cooperating with an internally threaded insert, fixed so as to be immobile in rotation and in translation inside said casing thereby immobilizing said threaded shaft, as well as a nut for driving said hollow, threaded shaft in rotation, said nut actuated from outside the casing for modifying the vertical position of said stop for limiting the upward stroke of the piston, the control shaft passing through said hollow externally threaded shaft.