Patent ID: 7674375

Claim:
An apparatus for measuring flow rates of a liquid in a chromatographic capillary system, comprising: a first pump in fluid communication to a first flow path carrying a first portion of a liquid from said first pump to a first sensor, said first sensor being in fluid communication with a fluidic tee, said first sensor operatively disposed in said first flow path and configured to produce a first signal; a first flow restriction element operatively disposed in said first flow path; a second pump in fluid communication to a second flow path carrying a second portion of a liquid from said second pump to a second sensor, said second sensor being in fluid communication with said fluidic tee, said second sensor operatively disposed in said second flow path and configured to produce a second signal; a second flow restriction element operatively disposed in said second flow path; a third sensor in fluid communication with said fluidic tee; and a subtractor means for measuring a pressure drop between said first sensor and said third sensor creating a first flow rate; a subtractor means for measuring a pressure drop between said second sensor and said third sensor creating a second flow rate wherein said first flow rate and said second flow rate are proportional to the flow delivered by said first pump and said second pump respectively; and means for controlling flow rates within each flow path with said first and second signal.