Experimental Determination of the Hydraulic Properties of Low Pressure, Lay-Flat Drip Irrigation Systems

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Journal/Book Title/Conference

Journal of Hydraulic Engineering






American Society of Civil Engineers

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The hydraulics of IDEal low-pressure drip irrigation system components were analyzed under controlled laboratory conditions. The hydraulic loss coefficient for the lateral-submain connector valves was determined based on laboratory measurements. It was found that the hydraulic loss due to friction in the lay-flat laterals can be accurately estimated with standard friction loss equations using a smaller effective diameter based on the wall thickness and inlet pressure head. The equivalent-length barb loss, expressed as an equivalent length of lateral, was calculated for button emitters, as well as for microtubes inserted to lengths of 5 and 10 cm. The head-discharge relationship and coefficient of manufacturer’s variation of prepunched lateral holes (without emitters), button emitters, and microtubes were determined. It was found that most of the head loss occurs in the connector valve, which has a relatively small hole through the hollow stopcock. The presence of manufacturing debris in the valve also increases the head loss and contributes to variability in the valve loss coefficient. The lateral cross-sectional area in the creases does not greatly impact the effective diameter for the 125-, 200-, and 250-��m250-μm wall thickness laterals. However, the use of the lateral height as effective diameter for the 500-��m500-μm sample resulted in significant overestimation of friction loss. The prepunched holes and the button emitters had very low manufacturer’s variation coefficients, but the microtube emitters showed excellent uniformity and are the emitter of choice among the tested alternatives. However, the microtube flow rate is relatively high and is more sensitive to pressure variation than the other emitter types.