Operational Characterization of Pressure Regulating Valves

The functionality of pressure regulating valves (PRVs) is important for proper uniformity and efciency of irrigation during center pivot irrigation, especially when the center pivot operates on sloping terrain. In practice, the regulated pressure at the PRV outlet is slightly infuenced by its inlet pressure, the fow rate through it, and hysteresis efects. Te objectives of this work were (a) to evaluate operational characteristics of PRVs based on requirements stated by ISO 10522 (1993) and (b) to model the regulated pressure as a function of inlet pressure and fow rate through the valve considering hysteresis. We carried out tests to evaluate regulation uniformity, regulation curve, hysteresis, and the regulated pressure as function of fow rate and inlet pressure. Te following three models of PRVs were evaluated: 10 PSI, 15 PSI, and 20 PSI. For each model, three samples were tested under increasing and decreasing conditions of inlet pressure, within the range from 49.03 to 784.53 kPa, with increments of 49.03 kPa. In addition, fow rates were tested within the range of 0 and 4 m3 h−1. From the gathered data, models to predict outlet pressure as a function of inlet pressure and fow rate were ftted.