Patent ID: 7549473

Claim:
A system for removing a liquid from a liquid reservoir by withdrawing limited quantities of the liquid in discrete steps, the system comprising: a dipping unit sized to be received in a passage to the liquid reservoir and oriented to have an upper end portion and a lower end portion when within the passage, the dipping unit comprising a chamber, means for enabling the liquid to enter the chamber when at least the lower end portion is submerged in the liquid within the liquid reservoir, and means for releasing the liquid from the chamber; and means for lowering and raising the dipping unit within the passage; wherein the releasing means comprises means for separating the upper and lower end portions of the dipping unit to define a separation therebetween through which the liquid is released from the chamber, the separating means being operable to define the separation by stopping upward movement of the lower end portion while not stopping upward movement of the upper end portion while the dipping unit is being raised by the lowering and raising means.