Relationship Between Pressure Regulator Performance And Nozzle Diameter Of A Water And Energy Saving Sprinkler Irrigation System

The altering and changing environmental conditions and scarcity of water,greatly requires a system that can manage irrigation systems efficiently and resourcefully.Automated irrigation systems are developed and advanced to enhance water use for agricultural crops.The practice of using pressure regulation in irrigation design can significantly improve system efficiency by limiting pressure fluctuation that reduces distribution uniformity(DU).With increasing emphasis on water and energy conservation,many systems are being designed or converted to operate under low pressure conditions.As a result,system pressure discrepancies have become a larger percentage of the total,requiring more precise regulation.Pressure regulators are used in center-pivot irrigation systems to adjust the operating pressure and discharge from the sprinkler with various pressures and sprinkler nozzle diameters.The key and main objective of the study was to investigate and study the relationship between pressure regulator performance and nozzle diameter of a sprinkler irrigation system.This was achieved by investigating the regulation uniformity and measuring the outlet pressure of the pressure regulator and the sprinkler discharge using different sprinkler nozzle diameters,spray performance of different nozzle sizes at different inlet pressures and regulation uniformity of a sprinkler irrigation system.Three pressure regulators with different nominal outlet pressure specifications,10 psi,15psi and 20 psi,were used in this investigation.Five nozzles of outlet diameters 3.18 mm,5.16 mm,5.56 mm,5.95 mm and 8.33 mm were installed on the sprinkler spray head to measure the actual outlet pressure and sprinkler discharge.The outlet pressure of the pressure regulator decreased as the nozzle diameter increased ultimately reducing the inner resistance of the sprinkler.When the nozzle diameter reached 5.16 mm,the differences between the actual outlet pressure and nominal outlet pressure became increasingly larger with increasing nozzle diameter.The discharge coefficients for the fixed spray plate sprinkler ranged from 0.91 to 0.98,0.93 to 0.99,and 0.94 to 0.99 using pressure regulators of specification 10 psi,15psi and 20 psi respectively.The discharge coefficients increased with the nozzle diameter,nozzle diameters larger than 5.56 mm,therefore the higher the pressure specification of the pressure regulator used,the higher the discharge coefficient of the sprinkler.The recommended applied inlet pressure,nominal outlet pressure plus 5psi,did not satisfy the desired outlet pressure for sprinkler operation when larger-diameter nozzles were installed on the sprinkler.Selecting the right regulator for the application is critical for consistent long-term system operation.Highquality low-pressure regulators must be harmonized or matched with corresponding low-pressure sprinklers to produce optimum results.Greater awareness,through education,of the impact that uncontrolled pressure has on system performance and how to accurately and appropriately apply pressure regulators is crucial for resource conservation.