valor de vazão em torno de 1.43 % para um primeiro cenário utilizando uma placa de orifício e ar como fluido, e de 0,073 % para um segundo cenário utilizando uma placa de orifício e gás natural como fluido, com relação aos valores obtidos através do instrumento multivariável 3095MV T M do fabricante Rosemount. Os valores de erro encontrados validam o método desenvolvido nessa dissertação. Palavras chave: Computador de vazão, foundation fieldbus, medidor de vazão, instrumento multivariável, Delta V T M , software sensor, rede neural artificial, HART, placa de orifício. vii Abstract This dissertation proposes the development of an artificial neural network (ANN) directed to foundation fieldbus environment for calculation of flow in closed ducts. The proposed methodology uses measurements of pressure, temperature and differential pressure, which are usually available in industrial plants. The main motivation of the use of neural networks lies in their low cost and simplicity of implementation, which allows the use of standard fieldbus blocks by just making the method independent of the manufacturer. It was used a multilayer perceptron network with backpropagation training and algorithm from Levenberg-Marquardt. The training was programmed in the software Matlab T M . The architecture of the ANN was determined by empirical methods by varying the number of neurons and neural layers until it reaches an acceptable error. After such trainings, it was developed a program to perform the flow calculations in an foundation fieldbus environment using Emerson Process Management's Delta V T M software. The results were obtained with an average relative error of flow rate of 1.43 % for the first scenario using an orifice plate and air as a process fluid, and 0.073 % for a second scenario using an orifice plate and natural gas as the fluid related to the values obtained from Rosemount 3095MV T M multivariable instrument. The values of error found validate the method developed in this dissertation.