Patent ID: 7607363

Claim:
A liquid volumetric device comprising a metering tube, a start sensor, an end sensor and a bath for storage of a sample to be metered, wherein the device further comprises: a vacuum chamber; and a pump for pumping out gas inside the vacuum chamber to form a negative pressure inside the vacuum chamber, wherein a start sensor and an end sensor respectively connect directly or indirectly to a lower portion and an upper portion of a metering tube, the upper portion of the metering tube connects directly or indirectly to the vacuum chamber and outside atmosphere, the lower portion of the metering tube connects directly or indirectly to a bath and the vacuum chamber, and at least one control mechanism for controlling flow or operation of the liquid volumetric device, wherein the at least one control mechanism comprises: a first valve comprising a common port which connects directly or indirectly to an upper portion of the metering tube, and two additional ports which respectively connect directly or indirectly to the vacuum chamber and the outside atmosphere, and a second valve comprising a common port which connects directly or indirectly to the lower portion of the metering tube and two additional ports which respectively connect directly or indirectly to the vacuum chamber and the bath.