Experimental apparatus for rapid prototyping of pressure-compensating inline drip irrigation emitters*

Pressure-compensating (PC) inline drip irrigation emitters supply water to crops at a constant flow rate, as long as the inlet pressure exceeds a minimum compensating pressure. Redesigning inline PC emitters to operate at lower pressure can significantly reduce the cost of drip irrigation systems, encouraging their adoption. Yet, design development is hindered by the emitters’ manufacturing complexity. Here we demonstrate an experimental apparatus that enables rapid, low-cost prototyping of inline PC emitters without the need for injection molding and bonding inside a pipe. Internal emitter geometry is CNC machined in aluminum and clamped between rigid plates with inlet and outlet openings. The required clamping pressure is determined by experiment. The apparatus is shown to accurately replicate the flow-pressure relationships of commercial inline emitters, making it suitable for prototyping new designs. Several applications of the experimental apparatus are presented, including evaluation of new emitter geometries, and characterization of emitter subcomponents (minor loss coefficients, membrane deflection) used to validate a theoretical model of passive flow control in PC emitters.