Patent US 3,940,600

Method and apparatus for blending, particularly liquid e.g. petroleum products. A number of qualities of the blended product are monitored, on line, to produce electrical signals representative of the respective qualities. The signals are operated on in a computer with a matrix which is an inversion of a matrix representative of the linear property indices of components of the blend to produce output control signals. The output control signals are fed to valves controlling the flow of components of the blend so as simultaneously to control the flow of all components to correct for any deviation of qualities without causing further deviations of other qualities of the blended product.