Nozzle Output Deviation

Nozzles wear. Abrasive formulations, ordinary grit in the water and simple erosion open the orifice, and an opened orifice passes more liquid at the same pressure. Because the orifice is the thing metering the application, a worn nozzle applies more than the sprayer was calibrated for, silently, everywhere along the boom that the wear has reached.

The standard check is to catch the output of every nozzle for a measured time — 30 seconds into a graduated jug is the usual method — at the rated pressure, and compare against the catalogue figure. The trade threshold is ten percent: a nozzle more than 10% above rated output is replaced. That threshold is not arbitrary. It is roughly the point where the applied rate leaves the ±5% window most labels allow while leaving room for ordinary measurement error in the check itself.

Two refinements are worth knowing. Compare nozzles against each other as well as against the catalogue, because uniformity across the boom matters as much as the average — a boom whose nozzles range from 5% under to 12% over is laying down stripes even if the mean is perfect. And replace nozzles as a set rather than individually once several are drifting, since a boom of mixed-age tips never sprays evenly again. A reading below rated is a different problem: orifices do not shrink, so a low nozzle is blocked, not worn, and wants cleaning with a soft brush — never a wire, which enlarges the orifice and turns a blockage into a permanent 15% overdose.