The challenge of cleaning direct-injection systems for pesticide application.

摘要

A direct injection system (DIS) for pesticide injection at all nozzles was set up in order to ascertain its ability to be cleaned. Under laboratory conditions, the system was contaminated with a safe-to-use salty polyvinylpyrrolidone-water solution as a test pesticide and then cleaned in two steps: (1) reclaiming the test pesticide by pushing it back into the pesticide tank using pressurized air (pre-cleaning) and (2) rinsing the contaminated part of the hydraulic system with water. Tests on a 3 m wide test bench included gravimetric and conductivity measurements to determine the amount of residues in the test section and test pesticide concentrations in the rinsing water. Mechanical action inside the test section was varied by (1) increasing the air pressure for pre-cleaning, (2) increasing the rinsing water pressure, and (3) employing pulsed water-air flow. Initial test pesticide concentrations in the rinsing water could be as high as 25%, which is more than in common spray mixes and requires further dilution. While continuous rinsing at higher pressures saved up to 10% of the water, rinsing the test section with pulsed water led to water savings of more than 50%. Rinsing turned out to be a time-consuming procedure, as it took almost 10 min for test pesticide concentrations in the rinsing water to approach 0%.