Abstract

Pipe network analysis is an essential aspect in the design of water distribution networks. The Hardy Cross method is one of the methods commonly employed in pipe network analysis. Two softwares are developed using the Hardy Cross method for analysis of flow in pipe networks based on FORTRAN and Visual BASIC (VB) programming languages. HARDY CROSS1 (FORTRAN-based) and PNET Expert (VB-based) are proposed. They differ only in the algorithm for computing the friction factor for head loss computation within pipeline; the former utilizes the Moody’s formulation while the later uses the Barr’s equation. Previous study proved that Moody’s equation has lower total errors than Barr’s equation, thus accounting for the differences in their algorithm implementation and results. Evaluation and analysis of these softwares using statistical methods (total error, coefficient of determination, coefficient of correlation, and reliability) are presented with particular attention to accuracy, validity and good fitness of each of the software. Two flow rate problems are used to demonstrate the applicability of the softwares. The study showed that the overall total errors (for the two Problems) for the flow rates are 1.33 and 0.60, for PNET Expert and HARDY CROSS1 respectively. Coefficients of determination values are 0.999976 for HARDY CROSS1 and 0.999948 PNET Expert. The values of coefficient of correlation were 0.999988 and 0.999974 for HARDY CROSS1 and PNET Expert respectively. It is then concluded that, the HARDY CROSS1 is the best option, because it gave the highest coefficient of determination, lowest total errors, and lowest reliability value. Its better performance is related to the algorithm utilized for head loss computation.

Key words: Hardy Cross, pipe network analysis, flow rate, statistical evaluation, head loss, friction factor.