Spray application manual
31 January 2025
Module 6: Pre-operational checks
6.4 Regular checks to perform during the season
Published 24 January 2025 | Last updated 20 January 2025
Before you start any job
Checks and maintenance
24 January 2025Sprayer checks & maintenance. Another video from GRDC's Spray Application GROWNOTES™ series.
Before you leave home
Confirm that the sprayer was decontaminated properly after the last job.
Always check the product labels and prepare spray plans and mixing plans (work out appropriate rate controller settings, flow rates and pressure, amounts of product to mix, water volumes required and the correct mixing order).
Always check the weather forecast.
Before you get in the sprayer
For diaphragm pumps, always check the oil level and condition in the oil bowl.
Check the tyre pressures and adjust as required.
Make sure the flush or fresh water tank is full.
Before you mix
Double-check the products supplied match the recommendation, and the rates to be mixed.
Make sure that appropriate personal protective equipment (PPE) is available and is worn by operators.
Before you spray
Calculate the required flow rate through the boom (L/min) and what the operating pressure should be at your normal spraying speeds. Have these figures easily visible while you spray. Many operators use a whiteboard marker to write these on the cab window, or have the spray plan in a handy spot.
Check the rate-controller settings, particularly the minimum hold (pressure, flow or speed), have been set to match the nozzles and the job.
Always check and set the minimum hold function
Measure and record the conditions at the site of application just before you start spraying.
Check the boom height (nozzle height) above the target (or false target) matches the job requirements and that the boom is level; check for wear points or if adjustments are required and check the height control is responding to stimulus (where fitted).
Checks to do during spraying
Continually check that the pressure and flow rate (L/min) on the rate controller are as calculated in the spray plan (ideally this pressure would be pressure at the nozzle).
Check height control and section control are working correctly.
Check nozzle patterns are OK and that there are no nozzle blockages.
Observe weather conditions and signs of possible changes, such as wind direction or wind speed or the onset of hazardous inversions.
For centrifugal pumps ensure oil temperature (or pressure) and pump RPM remain suitable for the job.
Tips
If the flow rate remains constant but the pressure begins to increase, check filters for blockages.
If flow rate remains constant and pressure drops dramatically, stop and check for leaks or blown hoses or fittings.
If pressure appears correct but flow rate is less than anticipated, check all sections are fully engaged and the section control/valves are responding correctly.
Use a paint pen to number the nozzle bodies across the boom, starting from the left-hand side (as if you are sitting in the cab of the sprayer). This makes it easier to identify which nozzles may need replacing if the pattern appears wrong while you are spraying.
Numbered nozzles on the boom
Plumbing-up-nozzle-numbering
24 January 2025Boom spray plumbing tip - nozzle numbering. Another video from GRDC's Spray Application GROWNOTES™ series.
Graham Betts: It's a really good idea and it makes a lot of sense to have the nozzle number mark next to the nozzle. Write every individual nozzle if you want to, but I just go and write even numbers. Why this is a great idea, is if you have a blocked nozzle, it makes it a lot easier to go and find where the problem is.
Checks at the end of rows or spray runs (as you slow down or speed up)
Check that the nozzles patterns are not collapsing and that the applied rate is not becoming excessive when you slow down to your minimum speed. This will be determined by where the minimum hold has been programmed to engage within the rate controller settings.
As you speed up, check the control valves are responding in a reasonable timeframe, and that the flow rate and pressure respond fast enough for the distance travelled before you get back up to your normal spraying speed.
Where you are having trouble returning to normal operating pressure quickly enough, adjustments to the regulating valve calibration factors or other settings in the rate controller may be required. Operators should consult the troubleshooting section
of the rate controller manual or contact the manufacturer if this continues to be a problem. Until such a problem is resolved, operators should consider using wider headlands.
Checks when spraying point rows or when spraying around/over obstacles for section and height control.
Always check that the auto-section control is operating correctly, and that the pressure returns to normal quickly enough as sections turn on and off. Some systems may require the operator to adjust the ‘look ahead’ function on the section control until they are happy with the performance.
Check the response of the height control system and the stability of the boom. If the boom is continually fighting itself to stay level, adjust the travel speed to see if this improves things, if not this problem may require the operator to check the position of the sensors or to recalibrate the height control system. Always consult the operation manual as different brands of height control may have different requirements.
At the end of each load
Check the controller for litres used against actual tank-mix volumes.
Check that hectares sprayed are as expected and that GPS and controller figures match.
For diaphragm pumps, check the oil level and condition in oil bowl at the end of each load.
Check over the spray system for obvious signs of leaks or damage.
Refill the water in the flush or fresh water tank.
Measure and record the weather conditions.
Measuring wind speed, direction and temperature
End of each day (but continuing the same tank mix)
Plan to finish with the tank as empty as possible by only mixing as much product as is required for the area to be treated. Where a part load is expected, many operators will adjust the application rate or tank-mix volumes so that all loads are equal in volume and the mixing requirements are the same for each load.
It's important to anticipate when conditions are likely to become unsuitable by consulting the weather forecast for the day. Never start a load when you expect the wind speed to drop, the wind direction to become unpredictable or when rain is predicted within the products' rain-fast period.
At the end of the day's spraying activities, always:
Make sure the sprayer is appropriately flushed with clean water before you leave the paddock and, where required, complete a decontamination.
Dispose of the tank contents and any rinsate after the cleaning process has been completed.
For more information and disposal of tank contents, go to Module 7: Mixing and decontamination. (LINK)
Before you get out of the sprayer, do some mental checks and calculations.
Check that the amount of product and water used is as expected for the area treated.
Check the rate controller and GPS records of areas treated and the volumes used match up.
Make sure all required records have been completed, including spray records.
Check over the sprayer.
Thoroughly check the plumbing system for leaks and deal with them before the next operation.
Check the boom for signs of fatigue and wear points, adjust dampeners if required.
Check the filters and screens (ensuring they have been flushed and PPE is used).
Check the nozzle diaphragms/non-drip valves are operating correctly.
Update the product inventory to match what has been used.
Blocked filters are a source of contamination
What to do if the job is interrupted (and product remains in the tank)
Wherever possible, avoid leaving pesticides in the tank overnight, especially without agitation constantly running. Where this is unavoidable, consider the following.
Assess what is in the tank mix and the water quality before you consider how to deal with the unsprayed contents of the spray tank. In addition to chemical breakdown and potential compatibility problems, leaving product in the tank greatly increases the effort required to decontaminate at the end of the spraying process.
It is not a good idea to leave Group 2, Group 4 herbicides or products formulated as suspension concentrates in the tank overnight.
For other products, a small amount of a single product or a tank mix of similar formulation types (not a tank mix of different formulations) may be able to remain in the main spray tank. However, the contents of the tank need to be able to be isolated from the rest of the spraying system so all the plumbing can be flushed with clean water.
Ideally, leaving product in the tank would only be considered for solo mixes of soluble liquids, such as products containing paraquat or glyphosate, and where the water quality will not adversely affect these products.
Leaving products formulated as emulsifiable concentrates (ECs) in the spray system for an extended period may ‘strip out’ herbicide residues from hoses and other rubber components that were not able to be removed during the decontamination process.
End of one job, but starting another one soon
Always complete a water flush in the paddock immediately after completing the last load. Ensure that the sprayer is fully decontaminated using the correct cleaning agents for the products used.
Find out more
For more information on decontamination procedures, go to Module 7: Mixing and decontamination.
Ensure decontamination was appropriate and consider the implications that the formulation of the next product to be used may have on potential residues in the tank or spray system.
Even after a complete and thorough decontamination it is possible that some residues may still be bound to the walls of the tank, plumbing or fittings. If the next product is to be applied to a crop and the tank mix contains an EC formulation, or perhaps a foliar fertiliser, it is possible that the solvents in the EC or the low pH values associated with foliar fertilisers could strip residues of previous products out of the sprayer components.
In these situations, it is useful to consider spraying some product onto a farm roadway, uncropped headland or fallow paddock, provided the label permits you to do this, before you enter the crop and apply the new tank mix.
Other things to check before changing products can include:
check filter and screen mesh requirements for new products;
check PPE required is available and serviceable;
check mixing order and calculations;
check mixing equipment is serviceable and clean; and
check spray plan for nozzle requirements and controller settings for the new product.
Checks to do before changing nozzle types for another job
After the decontamination has been completed:
check the nozzle patterns and do a rapid wear test on some of the current nozzles on the boom before changing to the new nozzle type;
check filter screen requirements for new products and nozzles;
check controller settings for new nozzle type (particularly the minimum hold requirements); and
make sure the diaphragms in the non-drip valves are clean and functioning correctly.
Using a tip tester to rapidly compare nozzle outputs
Also complete any checks included in this module 'Before you start any job'
Before putting the sprayer away for a while
It is important that the sprayer is put away in a state where it is ready to start another job immediately: finish clean so you can start clean.
Some things to consider before parking the sprayer for a period of time include:
has the sprayer been decontaminated and is clean;
what are the manufacturer’s maintenance requirements;
check cab air filters for remaining life/replacement;
check tyre wear and condition;
drain the pump and add a protectant to prevent corrosion (such as machining toll oil or radiator coolant); and ensure all other manufacturer’s service requirements are up to date and that parts are available for expected replacements.