The objective of this work was to develop an equation for the design of microtubes where the friction head loss in the microtube wall, the localized head loss and the velocity are explicit in the equation. The aim of this work was to offer a technical base for the development of a high irrigation technology with low cost. The work was carried out at the Rural Engineering Department of the ESALQ/USP. Based on the results of microtube tests the relation between pressure, length, flow and diameter for three different models of microtube head loss were established. The best representation of the microtube head loss was given by the model which considered the localized head loss with the coefficient K of the localized head loss equation depending on the Reynolds Number (RN). The other models tested were the model without localized head loss and the one considering the localized head loss with a constant K. The localized head loss is an important parameter which should be considered in the design of microtubes. Besides this, the coefficient of the localized head loss (K) is not a constant value but is a function of RN.
localized irrigation; hydraulics; microtubes
