Spray application manual
31 January 2025
Module 6: Pre-operational checks
6.2 Checks to do when the sprayer is first delivered
Published 05 November 2024 | Last updated 14 November 2024
If the sprayer is not new, always clean the sprayer externally with appropriate decontamination agents before doing any checks, measurements or adjustments.
Read the sprayer operation, maintenance and rate-controller manuals before operating the sprayer.
Check the manufacturer’s maintenance requirements and replacement schedules for items such as filters. Note these in a prominent place or in a maintenance register.
Check and record the current rate controller settings before doing anything else. Ideally these would be recorded in the rate-controller manual (and electronically), along with the date they were checked, before operating the sprayer.
Checks and measurements to do before you operate the spray system
Checking the boom
Check that the nozzles are mounted level across the boom.
Look from each end of the boom to make sure that the end nozzle on the boom wing is level or slightly elevated compared with the nozzles on the boom centre.
Boom level
Check boom stability, roll and yaw
Push down on the ends of the boom and ensure the boom returns to a level position. Adjust dampeners as required. Also check that the yaw (forward and backward movement) is not excessive – adjust tensioning devices where you are able to.
Check wear pads
Check that the wear pads on the boom mounting frame are not rubbing aggressively on the boom centre. If the wear pads are rubbing, adjust the boom wing(s) forward or back to relieve the pressure off the wear pad(s).
Check the boom’s ability to fold and unfold easily, ensuring no components are catching on boom supports, no hoses are crimping and that there is no damage to any of the nozzle bodies near the boom supports.
Check nozzle spacing and section widths
Depending on where the sprayer was manufactured nozzle spacing may be an imperial measurement, (e.g. 20 inches), but these are often entered into the rate controller as a metric unit, (e.g. 50 centimetres or 0.5 metres). A measurement of 20 inches is actually 0.508m, which introduces an error of 1.6 per cent to the applied rate before you even operate the sprayer, and the nozzles may not align correctly with rows planted on metric spacings in some situations.
Boom-Stability-adjusting-boom-wearpads
15 January 2025Boom stability - adjusting boom wear pads. Another video from GRDC's Spray Application GROWNOTES™ series.
Graham Betts: Part of boom stability is the wear pads here. They can actually cause some problems if they're rubbing on one edge and not on the other. What happens is, if they're rubbing there, that binds up with the centre and tries to move the whole centre rather than be free. To make sure it's adjusted correctly, you need to look at the wear side in there, look at the wear side in here, and in this case, it's rubbing on this side, so the boom would need to be adjusted so the boom wing is back a little bit to throw this centre section forward a bit to take the weight off there. When you test for this, push the boom down and make sure the boom centre doesn't move at all, and you know you've got that adjusted properly.
Measure nozzle spacing
Measure the exact spacing between all of the nozzle bodies. Also measure the distance from the centre of the boom to the outer nozzle body; for example for a 36.0m boom at a 0.5m nozzle spacing this measurement should be 17.75m. The accurate measurement of the sprayed width of the boom is important to ensure that the hectares recorded by the rate controller match the GPS.
The section widths to be entered into the rate controller should be the number of nozzles multiplied by the nozzle spacing on each section. If the nozzle spacing is not consistent, have this rectified by the dealer. If you have to use the sprayer before this can occur, use the number of nozzles multiplied by an average nozzle spacing.
Average nozzle spacing can be calculated by measuring the distance between outside nozzle centres on the section and dividing by the number of spaces between the nozzles.
Ensure you record this information and check that the section widths entered into the rate controller are correct.
Check the range of boom heights available (up and down travel)
Many booms will have a minimum height that they can be lowered to, ideally considered before purchase. However, if after delivery you discover the boom cannot be lowered below a minimum height of 0.7m or 0.8m above the ground, consider using narrower-angled nozzles for some applications to match the height above the actual target or top of the stubble, as well as the actual nozzle spacing.
Narrower fan angles are especially useful when applying pre-emergent herbicides with booms operating higher from the ground. In this case, the target is the soil and narrow fan angles will have more droplets travailing closer to vertical and therefore less likely to be intercepted by stubble and weeds.
For trailing rings, check the boom mount frame is vertical
If using a trailing sprayer, check that the boom mount frame on the back of the sprayer is perfectly vertical. If it is not, adjust the pull on the sprayer or tractor. This is very important to allow the boom to function at its best. Having the boom frame vertical should automatically make the main tank level.
For some trailing rigs used in row crops where the sprayer wheels follow the tractor wheels, the drawbar length should also be checked to ensure it matches the manufacturer’s specifications.
Height control (where fitted)
Check that the auto height control is responding to stimulus by placing your hand under each of the sensors. Make sure you are in a position where the boom cannot strike you if it raises suddenly.
Perform the auto-calibration function for the height controller to make sure it is able to perform as designed.
Checking the height control response
Auto-Height-Control-checking-response-and-calibration-requirements
15 January 2025Spray boom auto height control - checking response & calibration requirements. Another video from GRDC's Spray Application GROWNOTES™ series.
| Bill Gordon: We're just having a quick look at height control systems. This is a Raven set-up fitted to a Case sprayer. These guys send out ultrasonic signals down to the ground with the crop canopy to determine the boom height above the crop, and then they'll adjust automatically. This system has one on the main boom, we also have one here fitted out on the breakaway, and as a quick check, you can usually see how well they're working by the response, and she'll come back down. Now, if you have a boom strike or some of these units get bent, you need to recalibrate that height to make sure these are responding correctly. |
Height control systems are only as good as the boom centre and the auto calibration of the boom-height controller.
The ideal boom centre will allow the boom to be as independent from the sprayer as possible, so the boom can roll and stability is not affected when the terrain is uneven. It is useful to have some way to dampen the boom centre roll when the boom wings are being raised or lowered automatically or manually.
Tips
Check the auto boom-height control manual because each sensor brand has its own optimum sensor-mounting position. It is amazing how well the auto-boom height works after performing an auto calibration.
To assist in setting the boom to the correct height, install a piece of hose (not chain) between the last two nozzle bodies on the end of each boom wing. Cut the length of the hose to match how high the nozzle needs to be above the target (or false target) to achieve a double overlap.
Fitting a guide for suitable boom height
The pump (before operation)
Diaphragm pumps: check if a protectant has been placed in the pump and drain if necessary. Use an appropriate oil to fill the pump, and check the oil level and
condition in the oil bowl. For some pumps this may also require that bearings have been greased (e.g. some models of Hardi diaphragm pumps).
Centrifugal pumps: check if a protectant has been placed in the pump and drain if necessary before use. Check the requirements for hydraulic oil flow, and consider temperature impacts on the oil flow and pump RPM.
The plumbing
Ensure that all hose clamps and fittings have been tightened before operating the spray system to prevent potential leaks.
Tip
Use a lubricant on the hose clamp worm/thread before adjusting the hose clamp. Undo the hose clamp a bit before trying to tighten.
Check the nozzle bodies and diaphragms in the non-drip valves for debris and clean where required.
Ensure the spray lines and hoses are not interrupting the flow and nozzle spray pattern for example drooping hose at boom folds. Also check that hoses at the boom folds are not kinked or being pinched during folding and unfolding.
Electrical connections
Use a contact cleaner on all electrical connections that you have access to. This process may save a lot of troubleshooting time during the initial checks and during the season.
The tank
Inspect the tank to make sure it contains no debris. The tank of new sprayers should be flushed and drained before operating the spray system.
For used sprayers you will need to conduct a complete decontamination before inspecting the tank.
Check that the main tank and return lines to the tank can be isolated from the rest
of the spraying system. This will be important when doing repair and for flushing lines independently of the tank contents.
Ideally the tank design would be considered before purchase, ensuring there are no internal ledges or areas where products can become trapped. This includes the sump and drain outlets at the bottom of the tank.
Controller inputs
Check all devices that provide inputs to the controller (e.g. speed, flow, pressure, width) or those that may affect the accuracy of the calibration.
Speed
Even where a GPS is used for the speed input, it is useful to have a back-up method for speed input, just in case you lose the GPS signal and need to finish a job.
Where wheel sensors are fitted, ensure all magnets are in place and the sensor is intact.
Check the tyre circumference is correctly entered into the rate controller.
Make sure the tyre pressure is set to match the tyre manufacturer’s specifications and the actual weight and balance of the sprayer.
Tip
Impeller-based flow meters should be mounted vertically (with the impeller horizontal or parallel to the ground). The liquid flow should enter from the bottom and exit at the top. This reduces air in the line and prevents the build-up of solid materials in the flow meter itself. Ideally there will be a straight length of hose before the inlet to reduce turbulence; the length of straight hose should be about 10 times the diameter of the inlet.
Flow rate
Check how the flow meter is mounted and note the direction of flow. This will be important for later checks when you operate the sprayer.
Check and record the information on the flow meter (tag, stamp or sticker). The information on the flow meter should indicate a calibration factor (PPU or UPP) from the factory. This information should be recorded in the controller manual and will need to be checked against what has been entered into the rate controller when calibrating the sprayer output.
The calibration factors from a flow meter tag
Width
Ensure that the number of sections and the section widths that were measured when the sprayer was first checked match the section widths entered into the rate controller.
The total boom width entered into the rate controller should match the GPS.
GPS and auto-steer settings
Check that the distance between the sprayer tyres (centre to centre) matches the wheel tracks of other equipment. If this does not match it can affect boom stability and lead to poor auto-steering. Problems can often occur when operating machines based on metric measurements with other machines or equipment based on imperial measurements.
Operate the sprayer at different speeds to ensure the auto-steer performs well and identify where it may struggle, such as at lower or higher speeds.
Check that the physical boom width in the controller and the GPS settings match.
Tips
Care must be taken to carefully evaluate the accuracy of the GPS and the sprayed width of the boom. Nozzle spacing, position and number of nozzles must allow enough overlap of the spray patterns from the end nozzles. For example, when using a 36.0metre boom and a GPS with 2 centimetre accuracy, plumbing the boom with 73 nozzles at a 0.5m spacing (with a nozzle in the centre and 36 nozzles on either side of this) would give a sprayed width of 36.5m, which should be enough to provide a useful overlap of spray patterns.
If you are operating with a less accurate GPS, for example 10cm or 30cm, an overlap of just 0.5m (or 25cm at either end) may not be enough to ensure you get sufficient overlap of the sprayed width, leading to possible misses in the paddock.
Be exact in your measurements: 3.0m is not 120 inches, it is 118.1 inches. This can make a lot of difference to how auto-steer performs.
Weighing the sprayer ways to do it
15 January 2025Ways to weight the sprayer. Another video from GRDC's Spray Application GROWNOTES™ series.
Weight and balance
Weigh and record the sprayer weights (per wheel) with the main spray tank empty and boom folded and unfolded.
Record the information and specifications from the tyre, such as the tread width, ratio size, load index and speed symbol, and then, with all the weights you have measured, work out the required cold tyre pressure for the sprayer.
For more information on this process, go to Module 15: Weight, balance and tyres (LINK)
Tips
Use websites such as www.tirepressurecalculator.com as a guide to what cold tyre pressure is required.
Have a calibrated tyre pressure gauge that stays in the sprayer, so that the tyre pressure can be checked regularly.