Characterization of the microtube emitters used in a novel micro-sprinkler

• Published in: Irrigation science Vol. 27; no. 3; pp. 209 - 214
• Main Authors: de Almeida, Ceres Duarte Guedes Cabral, Botrel, Tarlei Arriel, Smith, Rod J
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01-03-2009; Springer-Verlag; Springer Nature B.V
• Subjects: Agriculture; Aquatic Pollution; Biomedical and Life Sciences; Climate Change; Drip irrigation; Environment; Friction; Hydraulics; Irrigation; Laboratory tests; Life Sciences; Original Paper; Pressure distribution; Pressure head; Studies; Sustainable Development; Waste Water Technology; Water Industry/Water Technologies; Water Management; Water Pollution Control; Emitter Discharge; Friction Factor; Lateral Line; Root Mean Square Error; LDPE
• ISSN: 0342-7188; 1432-1319
• DOI: 10.1007/s00271-008-0135-y

The microtube is a simple and cheap emitter that was widely used throughout the world in the early days of drip irrigation. Its length can be adjusted according to the pressure distribution along the lateral line and the discharge from the microtube can be adjusted by its length. This not only counters the pressure loss due to pipe friction but also makes it suitable for undulating and hilly conditions, where pressure in the lateral line varies considerably according to the differences in elevation. This is the major problem facing the designer, i.e., emitter flow changes as the acting pressure head changes. In this study, a novel micro-sprinkler system is proposed that uses microtube as the emitter and where the length of the microtube can be varied in response to pressure changes along the lateral to give uniformity of emitter discharges. The objective of this work is to develop and validate empirical and semi-theoretical equations for the emitter hydraulics. Laboratory testing of two microtube emitters of different diameter over a range of pressures and discharges was used in the development of the equations relating pressure and discharge, and pressure and length for these emitters. The equations proposed will be used in the design of the micro-sprinkler system, to determine the length of microtube required to give the nominal discharge for any given pressure. The semi-theoretical approach underlined the importance of accurate measurements of the microtube diameter and the uncertainty in the estimation of the friction factor for these tubes.