The Center for Irrigation Technology (CIT) at California State University, Fresno conducted tests to determine clogging resistance of the screen design of Ore-Max 16mm 1 GPH emitterline. The test protocol used is a variation of the standard CIT emitter grit test, modified to double the total loading of grit. This modified test protocol has been used in successfully developing 2 GPH Ore-Max emitterline to achieve maximum clogging resistance. This severe test, using a wide spectrum of grit sizes, was necessary in order to pick up differences in design of the Ore Max emitter, which is much more resistant to clogging than other emitters.
1 GPH Max Emitters are unique in that they have 185 screen openings over 330 degrees on the inside surface of the emitter leading to the flow path. This makes it very difficult to clog the water entry point. The new design utilizes the same number of screen openings but improves on the original by making the openings smaller. The screen openings are reduced from .040" x .040" to .040" x .020". The smaller screen openings reduce the size and amount of material that can enter the emitter flow path, further reducing the possibility of clogging.
The standard CIT test includes adding measured samples of standard sized aluminum oxide grit, in sequence, to a fixed amount of circulating water with pressure and temperature controlled. A test sample of emitterline with 20 emitters is part of the circulation system. Each grit size added increases the concentration by 250 PPM. The double grit test uses grit sizes 240, 220, 180, 150, 120, 100, 80, 70, 60, 54 and 46. The total concentration by the end of the test is 5500 PPM. The grit numbers correspond to particles that will pass through sieves from 140 mesh to 30 mesh. During the course of the test, flow measurements were taken after grit additions. After all the grit had been added and measurements taken, the grit was filtered from the circulating water and another flow measurement taken with clean water circulating.
|Emitter model||Emitters in test||Gph/Cv clean water||End of test no. plugged||Gph/Cv working emitters 5500 ppm grit||No. emitters plugged after cleaning water||Gph/Cv working emitters after cleaning water|
|16mm 1 GPH small screen design||20||1.05/.02||1 (5%)||1.04/.02||0||1.04/.02|
The tests show the new small screen design Max-Emitters are even more resistant to clogging under severe contaminant loads than the original design Max-Emitter. Not only is the percentage clogged very low but the remaining working emitters are extremely uniform, operating at normal flow rates. After two complete grit test cycles only one of the Max-Emitters was plugged and it cleared itself once clean water was flushed through the test system. Most emitters will completely plug during the first cycle of tests as the tests were designed to determine at what point an emitter will plug.
The unique design of the 16MM 1GPH Max-Emitter makes it possible to obtain the maximum distribution uniformity of heap leach mining solutions, even under heavy contaminant loading with low flow rate emitters.