Patent ID: 7826986
Filing Date: 2010-11-02
Classification: G01F,G05D

Abstract:
1. A method of operating a mass flow controller comprising, directing a portion of gas flow from a main flow line through a first tube, the first tube having a center portion, the center portion coupled to a first sensor; coupling a second tube comprising a second-tube-proximal-end and a second-tube-distal-end to the main flow line so that the second-tube-proximal-end is coupled to an upstream-main-flow-line-portion and the second-tube-distal-end is coupled to a second sensor; coupling a third tube comprising a third-tube-proximal-end and a third-tube-distal-end to a main flow line, the third-tube-proximal-end coupled to a downstream-main-flow-line-portion and the third-tube-distal-end coupled to the second sensor; processing a first signal from the first sensor; processing a second signal from the second sensor; sending the first and second signals to a digital controller; using at least one of the first and second signals to (i) operate a control valve and (ii) validate the proper operation of the mass flow controller.