String collectors to determine lag time of injection sprayers

Evaluation of injection lag time of direct injection sprayers is an important issue for successful variable rate sprayer technology. The lag and charge times of direct injection into a spray boom and direct-nozzle-injection sprayer systems were determined using string collectors sprayed with fluorescent dye along the sprayer path. Evaluations in the laboratory with the string system indicated that lag time was influenced by system flow rate and the volume of fluid in the sprayer distribution lines. Lag values determined with the cotton string collector method were closely correlated with the lag time calculated from line volumes and boom flows. Laboratory tests were also helpful in determining the number of nozzles that could be served from one injection point without excessive injection lag and charge times.