This project details the dynamic performance of two commercially available hydraulic flow-control
valves, DC motor driven and proportional solenoid type that are currently available for use on the variable-rate
granular spinner-disc fertilizer spreader used in the citrus groves of Florida. The dynamic behavior of these
valves was modeled as a first-order lag plus dead time response. The experimental data were collected by
issuing the valves a series of fixed step open commands and by monitoring the steady-state flowrate output of
the valves. Both valves were subjected to similar flowrate change commands and the outputs from the valves
were measured. The valve delay times ( o) were 0.08 s and 0.04 s and the first-order time constants (T) were
0.09 s and 0.02 s for the DC motor driven and proportional solenoid valve respectively. It was concluded that
the proportional solenoid valve’s performance was better.