Start / Machinery and application / Spraying, planting and spreading
Enter the spray volume, speed, and nozzle spacing to find out the flow each nozzle must deliver and the pressure needed.
Pre-sizing and estimating tool: the results do not replace a design, calculation, or report signed by a qualified professional, nor verification against the applicable standards.
Your nozzle curve from the square root law; the point marks the required flow, and the usual range is 2 to 6 bar.
Volume applied in L/ha at the working pressure; the dot marks the entered speed.
Drag the controls to simulate data different from what you entered (from 30% less to 30% more) and watch the result change instantly.
Working pressure required for combinations of speed and spray volume, with the nozzle, spacing and reference pressure you entered.
The calculation done in steps, with the values you entered.
The calculation memo gathers this page's inputs, results, equations, assumptions, and references, with fields for project, responsible person, and review. The full report also includes the charts and interpretations, in color. In the print window, choose Save as PDF.
Enter the desired spray volume in L/ha, the travel speed, and the nozzle spacing on the boom. Then type the nozzle's nominal flow and reference pressure, from the manufacturer's catalog. The calculator returns the flow each nozzle must deliver, the working pressure needed for that, and how many hectares each tank covers.
Volume of 100 L/ha at 8 km/h, nozzles at 0.5 m, nozzle with 0.8 L/min at 3 bar and a 600 L tank.
Nozzle flow = 8 × 0.5 × 100 ÷ 600 = 0.67 L/min. Pressure = 3 × (0.67 ÷ 0.8)² = 2.08 bar. Each tank covers 600 ÷ 100 = 6 ha.
| Change | Effect on volume | Effect on application |
|---|---|---|
| Increase the speed | falls | less coverage; the bar swings more |
| Increase the pressure | rises a little | finer droplets and more drift |
| Switch to a higher-flow nozzle | goes up | keeps the pressure within the recommended range |
| Increase the nozzle spacing | falls | requires more flow per nozzle for the same volume |
Good calibration is not enough if the weather is bad. As a general reference, spray with wind between 3 and 10 km/h, temperature below 30 °C and relative humidity above 55%. Outside these limits, drift and droplet evaporation increase.
With the volume set, calculate the product per tank in the tank mix.
For flat-fan nozzles, the usual range is 2 to 4 bar. Higher pressures produce fine droplets and increase drift.
From the manufacturer's catalog, by reference pressure. With the flow and reference pressure, the calculator adjusts the pressure for the desired volume.
Reduce the speed or raise the pressure. But flow grows with the square root of pressure: to double the flow you must quadruple the pressure, which worsens drift. If the pressure falls outside the range, switch to a nozzle with a higher flow.
It depends on the target, the product, and the equipment. Contact products need more coverage and, usually, more volume; systemic products need less. Follow the label and the technical recommendation.
Use moderate pressure, larger droplets, a low boom, and spray on days with light wind and good air humidity. Avoid spraying with wind above 10 km/h, strong heat or very dry air.
Collect the output of some nozzles for 1 minute at working pressure and compare it with the calculated value. Replace nozzles whose flow is more than 10% above nominal, because wear increases flow and worsens distribution.
Important notice: the Agrocalcs tools make estimates and preliminary sizing based on the data entered and on published engineering methods. They do not replace a design, a calculation report or a report signed by a qualified professional (CREA/ART), nor verification against the applicable technical standards and legislation, such as the Regulatory Standards of the Ministry of Labor. Material and fuel properties vary: check with the manufacturer or with analyses of your process before deciding. By using the site, you agree to the Terms of Use.
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