This work was developed to determine localized head losses in coaxial emitter integrated in polyethylene pipes. The localized head losses, for different flows, were obtained in four emitters' model, with seven replications. The amount of local losses caused by the emitter was calculated by the difference between the total measured head losses of the segment and the corresponding friction losses evaluated by the Darcy-Weisbach equation. Mathematical approaches were suggested to calculate the head loss using the kinetic load coefficient (K) and a constant value of equivalent length (Le). Not considering the localized head losses overestimated the maximum lateral lengths of 25.7%, for the pressure compensating emitters, and of 9.5%, for the not pressure compensating emitters. The calculation of localized head loss using the potential model to estimate the K value in function of obstruction index, showed good results, comparable to those obtained with the fitted K value by the data observed at the laboratory, resulting in small variations in the estimate of maximum lateral lengths for those two procedures.
drip irrigation; kinetic load coefficient; localized head loss; obstruction index; equivalent length
