Contribution to a standardized test protocol for assessing the sensitivity of drippers to clogging due to solid particles Clogging of emitters is pointed out as the main problem of drip irrigation, being the clogging by physical agents the most observed. In the market, there are several models of emitters, and the sensitivity to the clogging varies according to the water quality and the internal geometry of the emitter. In this context, the development of a methodology that evaluates the susceptibility of emitters to clogging is important, once that it can identify less sensitive emitter models to clogging. The standard ISO / DTR 21540 (under development) specifies laboratory and field methods for assessing the sensitivity of drippers to clogging caused by solid particles. The aim of this research was to identify limitations and propose improvements in the ISO / DTR 21540 laboratory test stage, in order to improve the repeatability of the results and contribute to a more robust and reliable methodology. In addition, to understand the solid particle clogging processes, were analyzed the main causes and regions of particle deposition along the labyrinths of the emitters. Two emitter models (Taldrip 0.55 L h-1 and Drip-Tech 1.55 L h-1) were evaluated. The material used as clogging agent was solid particles compound prepared from natural soil according to the ISO 11277 requirements. The clogging test consisted of four stages, lasting 40 hours each, in a combination of granulometric range (0-75, 75-125, 125-212 and 212-500 μm) and particle concentration (125, 250, 375 and 500 mg L-1), with higher risk of clogging at each stage. This research allowed to identify limitations and enunciate recommendations for improvement of the test protocol under discussion in ISO / DTR 21540. The accumulation of particles with relatively large dimensions (> 125 μm) was the main cause of clogging, reinforcing the probability that the grain size particle is a dominant factor in the clogging processes when using this test protocol.

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