Design and Construction of a Low-Cost Test Bench for Testing Agricultural Spray Nozzles

Droplet size distribution is probably the most important feature of a spray as it affects all aspects of a phytosanitary treatment, i.e., biological, environmental, and safety aspects. This study describes a low-cost laboratory test bench able to analyze agricultural spray nozzles under realistic conditions. The design of the equipment was mainly based on the ISO 5682-1 standard. It has a couple of 3 m long rails, along which the nozzle under test moves while spraying, controlled by a closed-loop position and speed controller. The drops were captured with three Petri dishes containing silicone oil, photographed by means of a digital single-lens reflex (DSLR) camera, and then analyzed with the ImageJ software in order to measure the usual spray parameters: the volumetric diameters, the Sauter mean diameter, and the number mean diameter. Spray trials and tuning of the system parameters were managed by means of a purposely designed user interface running on a Windows 10 PC. Some tests were carried out by using an Albuz ATR80 orange hollow cone nozzle at the working pressures of 0.3, 0.5, 1.0, and 1.5 MPa. The results about spray quality agree with the factory information, and the whole system, even if some aspects still need improvements, has proven reliable.