HYDRAULIC PERFORMANCE OF LOCALLY MADE LDPE-PIPES FOR DRIP IRRIGATION SYSTEMS

Abstract

LDPE pipes give controlled and efficient irrigation practices for plant-water requirement. All five sizes of pipes i.e. 13.0, 25.7, 31.5, 38 and 50 mm with wall thicknesses of 1.4, 1.8, 2.0, 2.5 and 3.0 mm respectively in 100 and 200 m lengths were selected for determination of pressure-discharge relationships, manufacturing coefficient of variation and friction coefficient. The pipes were operated at pressure ranging from 10 to 50 psi (7.00 - 35.00 meter head) with an increment of 5 psi. The discharge of different sizes of LDPE pipes was measured under various pressures. The average discharge of the pipes with 13.0, 25.7, 31.5, 38 and 50 mm pipe sizes between 10 to 50 psi pressure heads were 0.058, 0.301, 0.402, 0.909 and 2.076 Ips respectively for 100 meter pipe length and 0.056, 0.10, 0.13, 0.45 and 1.993 lps respectively for 200 meter pipe length. The average friction head loss of the pipes with 13.0, 25.7, 31.5, 38 and 50 mm pipe sizes between 10 to 50 psi pressure heads were 3.21, 2.51, 1.66, 3.99 and 3.64 meter per 100 meter pipe length and 6.44, 5.03, 3.15, 6.79 and 6.85 meter per 200 meter pipe length respectively. The average C-value of all sizes of selected pipes for both lengths between 10-50 psi was indicated 18% less than the recommend value. Results indicated that, the discharge, friction head losses and friction coefficient increased with the increase in pressure. This study helped describe the optimal pressure requirement to achieve the desirable discharge, low friction head losses and minimum friction coefficients.