Scottish Government

Visual and physical tests and practical water tests.

Hoses

Check ...

• For splits and cracks, particularly where booms fold

• Connections to ensure they are water tight

• For hose chafe, particularly in routing clips

Action:

• Replace damaged hoses

Filters

Check ...

• For missing filter elements and seals

• For leakage

• For blocked or damaged filters

Action:

• Replace any damaged or blocked filters

Tank

Check ...

• For fractures and any other damage

• The tank sits firmly in its mount

• The securing straps are correctly adjusted

• The agitation is working

• The tank is clean

Action:

• See the supplier/manufacturer now about fractures and any other repairs

Controls

Check ...

• The control circuitry (electrical, hydraulic or air) for correct operation

• Valves for both internal and external leaks

Action:

• Replace leaky valves - they waste money and are potentially dangerous to operators and the environment

Pump

Check ...

• Lubrication levels

• For leakages

• The air pressure in the pulsation chamber is at the recommended level

• The pump rotates freely without friction or noise. Do so by rotating manually or starting at low speed (corrosion may cause seizing up)

Pressure Gauge

The pressure gauge is vital for indicating whether the nozzles are delivering the correct amount of chemical per unit time while spraying.
If you have any doubts about the pressure gauge, replace it or refer the problem to the manufacturer or supplier.

Boom the boom suspension must operate smoothly to ensure a stable 'nozzle platform'.

Check ...

• Friction plates, dampers, shock absorbers, pivots and slides - and scheduled future maintenance

• Boom movement and stability*

• The boom folding mechanism

• The higher adjustment mechanism for correct functioning

• For distortion or sagging

• The break backs for correct operation

*The boom movement must be free but not too loose: - for a 12 metre boom, the tip should return to within 5 cm of its original height after a vertical displacement of 30 cm or more.

Boom Piping

Check ...

• The condition of all pipework

• The nozzle bodies for damage or loose fit

• For any damaged units, and replace them

• For leaks under pressure

Action:

• Remove the boom end caps and flush clean water through

Anti-drip valves

Avoid leaks by keeping these small valves, above or to one side of each nozzle, in good repair.
Damaged diaphragms and seats will lead to faulty functioning.
Examine all units under pressure to test for leaks and correct cut-off action.

Nozzles

Check ...

• All nozzles on the boom are the same

• All nozzles are in good condition, with no evidence of streaks or irregularities in the spray pattern

• All nozzles are clean and free from obstruction (note: clean with a soft brush or airline - don't damage nozzles by using wires or pins)

• All nozzles deliver to within + or - 5% of the manufacturer's chart value

Action:

• Always ensure the correct nozzles and operating pressure are selected before use. Have two or three sets of nozzles in stock to meet different spray qualities at different volume rates. Inspect nozzles throughout the season to avoid faults which could prove both costly and damaging to the environment if they develop unchecked

• Using water only, set to 'spray' at the specified pressure and collect the output from each nozzle in turn for a period of 60 seconds. Record each output volume and replace those outside the 5% tolerance around the manufacturer's chart value

Calibration

Where your sprayer has automatic controllers to monitor the speed of the sprayer and the flow, pressure and area sprayed, have you checked ...

• they are in good condition and properly maintained?

• they are frequently calibrated for accuracy, with calibration being checked after every 100 hectares' use?

• for leaks, blockages, variations in pressure or any minor damage during spraying?

In the booklet 'Boom Crop Sprayers', the British Crop Protection Council (address below) recommends a full calibration technique, summarised as follows:

• Read the label

• Measure the forward travel speed of the tractor with the booms out and over the field to be sprayed

• Calculate the nozzle output required

• Select the appropriate nozzle set

• Set the appropriate pressure

• Measure the nozzle output against time