Abstract

The selection of an economical pipe size for pumping plant and pipelines (mains and submains) in pressurized irrigation system should be based on careful economic analysis. A small diameter pipe may require a lower initial investment, but the head loss due to friction is greater and this increases the power cost. Similarly, a larger pipe involves a higher initial investment with less power cost. In this study, various mathematical or empirical models were formulated to select an economical pipe based on pipe diameter. These models were formulated for six different pipe materials such as reinforced cement concrete non pressure (RCC-NP2), RCC-NP3, galvanized iron, poly vinyl chloride (PVC) grey plain, PVC grey socket, and PVC grey rubber riveted (RR) joint. Each pipe material with diameters 40, 50, 75, 90,110, and 160 mm were selected to derive mathematical formulae. The prices for the different pipe materials of varying sizes were collected from various retailer shops. Further, mathematical formulation was done for calculating fixed and operating costs of these six pipe materials based on diameter of pipe, flow rate, electricity cost, and length of pipe.

Key word: Pressurized irrigation system, pipes, fixed cost, variable cost, diameter of pipe.