Comportamento hidráulico de registros de gaveta, esfera e pressão

Abstract

Valves are accessories that establish, control and block the flow at a pipeline; therefore, they must be chosen carefully, not only due to their physical characteristics, but also because of their operational and hydraulic behavior. Thus, the objective of this work was to evaluate the hydraulic behavior of gate, ball and pressure valves. Flowrate evaluations were carried out with four openings (25%, 50%, 75% and 100%) of the tested valves, with five replications. To estimate the major head losses, a differential "U" tube mercury manometer was used, without the presence of a valve. The calculation of the minor head loss (hfL) was performed by measuring the values of the total head loss (hfT) in the section where the valve was located, from the subtraction of the major head loss (hfC) and other accidental losses, by the presence of other accessories. Average values of the coefficient "K" of minor head loss were estimated, as well as the Equivalent Length (Leq). In addition, mathematical models were fitted to determine the head loss coefficients (K and Leq), using the Reynolds number (Re) and average flow velocity in the pipe section as independent variables. For the estimative of the tested valves coefficients, higher values were obtained in the 25% openings due to the smaller section area and the lower flow velocity. For 100% and 75% openings, the lowest values were obtained. When analyzing the models for estimating the variables related to the minor head loss, the independent variable flow velocity, in general, led to a better estimate compared to the Reynolds number.