Patent ID: 11951470
Assignee: nan
Field: Chemical engineering (Chemistry)
Classification: CPC B | IPC B

Claim 11:
12. A mechanism for accurately and reliably metering of liquid volumes comprising:
a cylinder holding a seal at each end that defines a chamber and takes into the chamber a piston from above and a tube from below, the diameter of the piston being less than the diameter of the tube, and the cylinder, piston and tube being concentric and coaxial to each other,
the cylinder configured and arranged to slidably move up over said piston and tube to release a portion of the tube from the cylinder while taking in an additional similar portion of the piston, thereby increasing a volume of air in the chamber and to create a negative pressure or vacuum therein,
the cylinder further configured and arranged to slidably move down over the piston and tube to release a portion of the piston from the cylinder while taking in an additional similar portion of the tube, thereby reducing the volume of air in the chamber and to create a positive pressure therein,
said piston configured and arranged to move with the cylinder by a same distance as the cylinder moves, so that the tube moves alone within the cylinder with no offset movement of the piston in the cylinder, thereby causing a change in the volume of air in the chamber.