A Step-by-Step Guide: How to Calibrate Your Sprayer

JUNE 2018

An accurate calibration is essential for any spraying function as it ensures that the chemical is applied at the rate intended on the product label. Application in excess of the recommended rate is prohibited, as it can damage plants/foliage and it is uneconomical.

But what does it actually mean to calibrate your sprayer?

This is a calculation to ensure you are applying the correct amount of liquid (chemical + water) to a certain size or area. So here’s a few basic steps to help you calibrate your sprayer:

 

Example Calculation

Step 1: Check the Calibration on Your Sprayer

Check Nozzle Output

Fill the spray tank with clean water. Run the sprayer at the correct pressure with all nozzles operating.
Place a measuring jug under first nozzle for one minute. Measure how much water is in the jug.
Repeat for all nozzles. Nozzle output should not vary by more than 10%. If it does, the nozzle could be worn or damaged and should be replaced. All nozzles on the boom should have a similar output.
Add all the jug measurements to find the total sprayer output in litres per minute.
 
Average Output = 41.9 L/min
 

 

 

 

 

 

Calibrate the Sprayer

Speed (km/h) = 360 divided by Time (seconds) and measure Time per 100 Metres
 
Example:
Speed = (360 ÷ 41.9) = 8.6 Km/h
Output = (1.40 x 600 ÷ 0.5 ÷ 8.6) = 195.35L/min
 

Step 2: Get the Initial Data

 

 

 

 

 

 
 

Read the Label

This will give you the Spray Volume, Product Dose & Spray Quality
 
Example:
Spray Volume = 200 Litres / Hectare
Product Dosage = 50 Litres / Hectare
Spray Quality = Medium
 

 

 

 

 

 

Measure Time

Measure time (in seconds) per 100 Metres
 
Example:
Time = 41.9 Seconds
 

 

 

 

 

 

Calculate Speed

Calculate Speed – SPEED (km/h) = 360 divided by TIME (seconds)
 
Example:
Speed = (360 ÷ 41.9) = 8.6 km/h
 

 

 

 

 

 
 

Nozzle Spacing

Measure the nozzle SPACING – Usually 0.5 metres (50cm)
 
Example:
Spacing = 0.5 metres
 

 

 

 

 

 

Measure Quantity per Minute

Measure TIME per 100 Metres – OUTPUT (L/min) = VOLUME (L/hec) x SPEED (km/h) x SPACE (metres) ÷ 600

 

Example:
Quantity = (200 x 8.6 x 0.5 ÷ 600)  =  1.43 L/min