US Patent 7264224 Valve with offset venturi

A valve is disclosed having a valve closing member that divides the valve bore into passageways of unequal cross sectional areas when in an open position. A venturi is positioned within the valve bore upstream of the valve closing member. The throat of the venturi may be within one pipe diameter of the valve closing member. The venturi is offset from the bore centerline so as to align with the larger of the two passageways. Turbulence is reduced allowing more accurate pressure measurements to be made within the venturi yielding more accurate determination of volumetric flow rates.