Quantificação da perda de carga em conexões de pvc soldável: determinação dos coeficientes k e comprimentos equivalentes

Abstract

In hydraulic design, the determination of the load losses occurring along the pipes and at localized points is necessary for the good functionality of a water distribution system. The phenomenon is called a loss of charge and is divided into distributed and localized loss of charge. At points where there is a change in direction of the flow, the hydraulic connections are inserted in a way to allow the flow to reach the distribution point. It is verified in norms and consecrated literatures, values of hydraulic parameters necessary in the dimensioning for more usual connections. However, some connections do not have quantified parameters, such as the Curve Transposition type connection. Thus, the present study aimed to determine the coefficient of loss of load K and equivalent length for two connections: knee 90° and Transposition Curve. For the connection of type knee 90° nominal diameter 32mm, the experimental results of equivalent length to that verified in NBR 5626: 1998 and the coefficient K based on consecrated bibliographies were verified. Also for Knee 90°, load loss estimates were also made using standard equations in hydraulic system designs to analyze the performance of the equations versus the experimental data. For the Transposition Curve type connection, the load losses for the nominal diameters 20, 25 and 32mm were quantified in the laboratory and the experimental values were checked for the coefficients K and equivalent lengths. At the end of the study, it was verified that for the experimental conditions verified, the connection of the knee 90 ° type presented values of equivalent experimental length inferior to the one verified in normative. For the estimation of the loss of load, the loss for knee 90°, using a value corresponding to the diameter verified in the standard, was verified that the Fair-Whipple-Hsiao equation approached the experimental data. For the transposition curve type binding, through the observed loss of charge for the binding assessed, a significant equivalent length value was found, showing a significance e need of a study to determine the unquantified hydraulic parameters for this binding.