Experimental Determination of the Hydraulic Properties of Low-Pressure, Lay-Flat Drip Irrigation Systems
Publication: Journal of Irrigation and Drainage Engineering
Volume 137, Issue 1
Abstract
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 wall thickness laterals. However, the use of the lateral height as effective diameter for the 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.
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Acknowledgments
Funding and laboratory facilities for the work reported in this article were provided by Grant No. UNSPECIFIEDProject 798 of the Utah Agricultural Experiment Station and the Utah Water Research Laboratory.UNSPECIFIED
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Published In
Journal of Irrigation and Drainage Engineering
Volume 137 • Issue 1 • January 2011
Pages: 37 - 48
Copyright
© 2011 ASCE.
History
Received: Jun 10, 2009
Accepted: Jun 4, 2010
Published online: Jun 9, 2010
Published in print: Jan 2011
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