Chemical Flow Control System for Injection-Type Sprayers

Two peristaltic pumps were tested to determine their accuracies in metering three liquid herbicides for injection-type sprayers. To maintain acceptable chemical application accuracy from either pump, recalibration is necessary if the formulation or its temperature changes. An experimental thermal flowmeter was developed and evaluated along with turbine and piston flowmeters. The piston flowmeter had the best linearity and smallest time constant. A system to control the flow rate of the injected chemical is proposed and was simulated to determine its dynamic response. The proposed chemical metering system, coupled with plumbing systems of sprayers used by private and commercial applicators, were simulated to predict chemical application accuracies.