Patent ID: 8602633

Claim:
An apparatus for combining at least two materials together, said at least two materials comprising a major material and at least one minor material, said apparatus being characterized by the absence of flow meters, flow control valves and dynamic mix tanks, said apparatus comprising a computer, a confluence region where said at least two materials come together, wherein said apparatus comprises positive displacement pumps which provide each of said materials at a transient flow rate whereby the amount of each of said materials blended per unit time is controlled by a command signal from said computer to said pumps and is varied either to be greater than or less than a prior rate of blending said materials, whereby said transient flow rate produces an instantaneous error and a cumulative error between a command signal sent from said computer, said command signal having a setpoint which is changed at time T=0 and a measured flow rate, said instantaneous error being not more than: IE< A*M *exp(− t /τ) Where IE is the instantaneous error in volume per unit time, and A is the magnitude of the setpoint change at time zero, normalized to unity, M is a scale factor ranging from about 0.1 to about 0.5, t is the instantaneous time in seconds, not to exceed about 1.5*τ, τ is a time constant ranging from about 0.1 to about 1.0 seconds, said apparatus comprising a common outlet for said at least two materials after the same are combined, said common outlet being downstream from said confluence region.