Calibration of Equipment

Calibration of Equipment

Country Co • Nov 02, 2021
Blog  » Calibration of Equipment

Calibration of equipment is a necessary component of any successful spray application. The below techniques are common methods employed.

Reasons for Calibrating Chemical Application Equipment.

  • Save money, by not overdosing
  • Ensure the correct dose
  • Less resistance
  • Avoid wasting time and effort
  • Avoid risking markets, especially international markets
  • Avoid loss of product/income
  • Avoid damage to crops and livestock
  • Safer for the consumer
  • Safer for the environment


Boom Sprayers

Hints

SPOTON Sprayer Calibrator Model SC-1


1. Allow time (1 hour+ depending on boom width)

Calibrating boom sprayers can take significant time as some of the larger booms may have more than 80 nozzles to record flow rates from. If using a jug to test at litres/min, even a 15 second test will require more than 20 minutes for this part alone.

The use of flow rate meters such as “Spot On” will reduce the time taken and increase accuracy.

2. Ensure pressure is stable.

Run the pump at the desired pressure that will be targeted in the application. Ensure that all the air has been purged from the system prior to commencing flow rate tests. This may take several minutes before stable rate is established.


3. Allowable Variation in nozzles flowrate.

Ensure the boom has nozzles that are within 10% variation, a quick way of checking is to see if all the flowrates recorded are within 110% (1.1 times) the lowest recorded flowrate.


For example lowest flowrate recorded was 1 Litre/min the maximum rate needs to be within 1.1 Litres/min. Any nozzles outside the range need to be changed.


When selecting which nozzles need changing if a high number of nozzles are beyond the 110% of the lowest this would indicate that the lowest flowrate nozzle needs to be replaced.


Step 1  Calculate Rate/Ha

Technique 1


An example calculation 

Boom output per minute = 47Ltrs/min

Swath Width = 24 metres

Speed = 8 Km/Hr




Rate per Hectare =

Step 1 

600 X 47 = 28,200

Step 2 

24 X 18 = 432

Step 3 

28,200 (answer to step 1) divided by 432 (answer to step 2)

28,200 / 432 = 65.27 Litres / Ha


Boom Output per minute = measure the total flowrate of all nozzles over the boom. 

For example a boom that has 47 nozzles will require all 47 to measured and the flowrates added together.


Swath Width = in metres measure the pattern at target. 

This can be calculated by (number of nozzles +1) multiplied by spacing of nozzles (in metres).

For example on a boom with 47 nozzles set at 50cm the swath width is 24 metres, calculated as below

(47 + 1) x 0.5 

Step 1 

Add 47 + 1 = 48

Step 2 

Multiply 48 by 0.5 = 24 metres   (0.5 is 50cm in metres)


Speed = Km/Hr

In most cases this will be decided by choice of operator depending on field conditions.

Speed can be calculated using the below formula.

Distance (in metres) x 3.6 divided by  time taken in seconds.

Hint use 100 metres

This formula can be simplified to 360 divided by time taken to travel 100 metres.

For example set the tractor to the correct gear and rpm that will be used in operation then time in seconds how long the tractor takes over 100 metres.  (say this was 20 seconds)

Then the calculation would be 360 divided by 20 seconds = 18 Km/Hr.

Technique 2

Calibration of Water Application Rate for Spray Equipment
Total Nozzle Output ÷ Distance Travelled ÷ Swath width x 10,000 = Water Application Rate
(in litres/min) ÷ (in meters/min) ÷ (in meters) x 10,000 =
47 ÷ 300 ÷ 24 x 10,000 = 65.27

Output

Measure in Litres per minute the total volume of all nozzles over the boom.

For example, a 24metre boom with 47 nozzles will require all 47 nozzles to be measured.

 As part of this process, it is important to make sure that all nozzles are within 10% variation this is 5% above the average and 5% below the average.

 

Distance = Speed in metres per minute. Can be calculated as option A or B

 

Option A Should you know your speed in Km/Hr

Km/Hr conversion to metres/minute = Km/Hr multiplied by 16.6666 = metres/ minute

For example, 18Km/Hr = 18 x 16.6666 = 299.9988 rounded to 300 metres / minute.

 

Option B Measured using 100 metres and timed in seconds

Formula is (60 divided by time taken) multiplied by 100

For example, tractor travelled 100 metres in 20 seconds

Calculation

(60 / 20) X 100 = 300

 

Swath Width = in metres measure the pattern at target.

This can be calculated by (number of nozzles +1) multiplied by spacing of nozzles (in metres).

For example on a boom with 47 nozzles set at 50cm the swath width is 24 metres, calculated as below

(47 + 1) x 0.5

Step 1

Add 47 + 1 = 48

Step 2

Multiply 48 by 0.5 = 24 metres  (0.5 is 50cm in metres)

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