Histerese em válvulas reguladoras de pressão utilizadas em pivô central

Abstract

The center pivot irrigation system has been gaining importance due to its technical and economic viability. One of the characteristics of this system is the coverage of large areas and the technological level that has been implemented in this system. The technology of water application through the use of pressure regulating valves, which stabilizes the blade applied along the entire lateral line, is an indispensable technology for irrigation using this system. However, there is still a lack of research to clarify the flow variation in pressure regulating valves due to the pressure variation in their upstream. Thus, as this work aimed to study the magnitude of the variation in the flow of the emitter sets plus pressure regulating valves used in central pivot due to the variation of pressure upstream of the emitters plus the pressure regulating valves, which is called the phenomenon of hysteresis. Simulations of the effects of this phenomenon were also carried out for the area with a sloping profile in a central pivot equipment. The magnitude of the flow variation in the emitters plus the valves due to hysteresis was evaluated by directly obtaining the flow with the variation in the working pressure of the system. The tests were carried out at the UFLA Irrigation laboratory, the experiment was composed of 3 pressure regulating valves 10 PSI, emitters with three different flows and three repetitions. In the simulation of the effects of hysteresis on the flow in a central pivot in an area with a sloping profile, the pressures upstream of the first emitters plus the pressure regulating valves of the spans were collected, thus having 8 collection points. It was possible to analyze and describe for the emitter sets plus pressure regulator valves studied the magnitude of the flow variation due to the hysteresis phenomenon. Data treatment allowed data grouping and generalizations of the hysteresis phenomenon for any sets of emitters plus pressure regulating valves. With the simulations of the flow variation according to the conditions of pressure variation in the valve upstream in an area with a sloping profile obtained from a central pivot equipment, it was possible to identify the spatial influence, in the field, of the hysteresis phenomenon. Thus, it is possible to carry out management considering the spatiality of the occurrence of the hysteresis phenomenon in the area, thus minimizing its impacts on the uniformity of application.