ABSTRACT
RESUMO A medição de vazão é fundamental para a gestão de processos que envolvem fluidos. Em empresas de saneamento, contabilizar as entradas e saídas de água é essencial para gerir faturamentos e perdas, podendo ser mensurada por meio de variados instrumentos com diferentes princípios de aplicação. Dados os altos custos de aquisição dos macromedidores usuais, bem como as dificuldades de instalação e manutenção, a macromedição no Brasil é deficiente. O tubo Pitot Cole é um medidor capaz de determinar a vazão em tubulações pelo diferencial de pressão. Suas principais vantagens são o baixo custo e a fácil instalação, que pode ocorrer com a tubulação em carga. Em contrapartida, suas peças são frágeis e de formato complexo. Este trabalho propõe a construção de um medidor de vazão simples e robusto com tomadas de pressão instaladas em faces opostas de um prisma hexagonal e avalia a viabilidade na mediação de vazão. Os resultados mostraram-se promissores dadas a estabilidade e a forte correlação linear obtidas no coeficiente de calibração.
ABSTRACT Flow measurements are essential for processes management involving fluids. In water companies, measuring inlets and outlets of water is essential to manage revenue and water losses. The water can be measured through diverse instruments with different application principles. Due to the high acquisition costs of the usual water flow meters, as well the difficulties of installation and maintenance, macro meter in Brazil is deficient. The Pitot Cole Tube is able to determine flow in pipes through the pressure differential. The main advantages are the low cost and easy installation, that may occur with the pipe under load. However, its peaces are fragile and complex. This paper propose the construction of a simple and robust instrument to measure the water flow. The prototype is build with pressure plugs installed on opposite faces of a hexagonal prism, then is evaluated of its effectiveness in water flow measurements. The results were promising given the stability obtained in the calibration coefficient.
ABSTRACT
Currently, hydrocephalus treatment is performed mainly with ventriculoperitoneal shunting. This experimental study aims at assessing whether the experimental model of hydrocephalus in dogs is applicable to the laboratory study of the retrograde ventriculosinusal shunt (RVSS). Four mongrel dogs were assessed. After randomization, the animals were divided into two groups: an experimental group that underwent the induction of hydrocephalus/RVSS and a control group, for the measurement of the mean arterial pressure, intracranial pressure and pressure in the superior sagittal sinus (SSS). The controls presented a mean arterial pressure of 68 mm Hg (71 and 65), an intracranial pressure of 163 mm H2O (149.6 and 176.8) and a pressure at the SSS of 40 mm H2O (40 and 40). The kaolin injection into the cisterna magna at a concentration of 0.3 mg/ml was capable of inducing the clinical and radiological mechanism of hydrocephalus (intracranial pressure = 250 mm H2O, pressure at the SSS = 50 mm H2O). The caliber of the SSS was 2.5 ± 1.0 mm. The fact that the SSS caliber of the dog was the same size as the external diameter of the catheter used resulted in the complete obstruction of the SSS when the catheter was inserted. We believe we could design and perform an experimental model to test the RVSS. It is applicable and feasible. The model of hydrocephalus, the surgical apparatus and the scenario were adequate, but the shunt system needs to be proportionally made to the canine anatomy.