Development of a real-time chemical injection system for air-assisted variable-rate sprayers

Abstract

Abstract. Chemical injection system is an effective method to minimize chemical waste and reduce the environmental pollution in pesticide spray applications. A microprocessor controlled injection system implementing a ceramic piston metering pump was developed to accurately dispense chemicals to be mixed with water proportionally in real time for air-assisted variable-rate sprayers used in nurseries and orchards. Differently from conventional direct in-line injection systems, the new system mixed water and chemicals in an injection chamber first and then transferred the spray mixture into two small transition tanks for the sprayer pump to discharge. The mixture concentration in the transition tanks was maintained as a constant for simplifying chemical pumping process when the sprayer was providing variable-rate outputs. A touch screen integrated with an embedded computer was used to allow the operator to interface with the injection system. Experiments were conducted with various viscous fluids to verify the system accuracy and reliability.