Evaluation of various types of imported emitters used in drip irrigation systems in Libya

Abstract

This study was carried out to evaluate various types of imported emitters used in drip irrigation systems in Libya.  Two types of point source emitters were evaluated; namely on-line emitters and in-line emitters.  One model of the in-line emitters were evaluated.  The evaluated model of the in-line emitters were manufactured in Egypt.  In this model, the emitters were desgined to be attached to the lateral tube line from two sides.  Three models of on-line emitters were tesed in this study.  The evaluated models of on-line emitters were manufactured in Egypt, Greece, and Italy.  A sample of fifty new emitters from each model were tested in laboratory.  Each emitter was operated alone for twenty minutes at a reference pressure head of 10.7 meters.  The discharged water from each emitter was collected and measured.  The coefficient of manufacturing variation for each sample was calculated from the discharge data (converted to liter per hour) of the samples.  To determine emitter discharge exponent for each sample, two emitters of each type were opertaed (alone) at two different pressure heads; namely 2 and 5 meters.  The results showed that the coefficient of manufacturing variation was 0.32 for the in-line Egyption emitters and 0.23, 0.15 and 0.11 for the Greak, Egyption and Italyan on-line emitters, respectively.  According to the American Society of Agricultural Eingineers, the in-line Egyption emitters and the Greak on-line emitters can be classified as unacceptable whereas the on-line emitters were classified as marginal and poor quality for Italian and Egyption on-line emitters, respectively.  This classification rely on emitter coefficient of manufacturing variation which was determined in this study.  The emitter discharge exponents were 0.63 for the Egyption in-line emitters and 0.43, 0.40 and 0.31 for the on-line emitters imported from Egypt, Greece and Italy, respectively.  Therefore, it can be concluded that the the discharges of the on-line tested emitters are less sensitve to variation in operating pressure than the in-line Egyption emitters.  This is due to low emitter discharge exponents of the on-line emitters.