The Effects of Water Temperature on Discharge and Uniformity Parameters of Emitters with Different Discharges, Types and Distances

The research was conducted on emitter testing bench established in Irrigation laboratory, Suleyman Demirel University, Isparta, Turkey. In the study, discharge equations (q= kHx), standard temperature discharge index (TDI, standard temperature is 20 oC) and uniformity parameters such as coefficient of manufacturing variation (CV), standard uniformity (Us), Christiansen uniformity (Cu) and emission uniformity (CUE) of in-line emitters with different discharges (D1: 2.4 L h-1 and D2: 4.0 L h-1), types (TB: Pressure compensating, TT: Non-pressure compensating) and distances (A1: 20 cm, A2: 33 cm and A3: 50 cm) under different water temperatures (20, 30, 40 and 50 oC) were determined. Effects of different pressures (from 80 to 200 kPa) on discharge of the emitters were also investigated. Discharges of non-pressure compensating emitters were increased by increasing pressure (r≈ 0.99). Although discharge was stable under high or recommended pressure in pressure compensating emitters, there was an increasing trend in emitter discharge under low pressure like non-pressure compensating emitters. Linear regressions were obtained between discharge and water temperature in non-pressure compensating and pressure compensating emitters (r≈ 0.99). Emitter discharge increased due to water temperature increase approximately 5 and 3% in non-pressure compensating and pressure compensating emitters, respectively. TDI values of non-pressure compensating emitters increased between 0.04 and 0.06 with increasing water temperature. In pressure compensating emitters, TDI values decreased 0.02 in D1A1TB emitter, did not change in D1A2TB emitter, and increased between 0.01 and 0.02 in other four emitters with increasing water temperature. Cv, Us, Cu and CUE values of the emitters under different water temperatures ranged between 0.023-0.044, 95.6-97.7%, 96.6-98.1% and 89.3-96.0%, respectively. Significant differences were obtained for each of these parameters in different water temperatures, emitter types and emitter distances. Generally, uniformity parameters improved in high water temperatures and the highest values of uniformity parameters were obtained from A2 emitter distance in the tested emitters (P<0.01).