Band and Overall Spraying:

Calibration is vital to ensure that the nozzles are spraying the correct amounts of fluid. It should be undertaken every 100 hectares (250 acres) using clean water. At the same time, nozzles should be checked for wear and visible damage.

(a) Before calibrating nozzles, ensure that liquid has clear passage by checking and cleaning all filters and removing any restrictions (hose kinks etc) in the feed and delivery lines. Check also for air leaks and pump performance.

(b) Bearing in mind your operational speed and pressure range, use nozzle selection charts to

find the correct flow per minute to produce the application rate you require.

(c) Set your operating pressure

(d) Using a watch and measuring jug or cylinder, check the output of a single nozzle at that pressure. If the output varies slightly, small pressure adjustments may be made within the recommended pressure range until the correct output is attained.

(e) If the pressure range is outside that recommended to obtain the correct nozzle output, then change to the appropriate nozzle size. This should be done by reference to nozzle selection charts. It may then be necessary to re-adjust the pressure setting if your nozzle spacing is other than at 50 cm centres.

(f) Once the correct output has been attained from the test nozzle, all other nozzles should be assessed. If any nozzle output varies by more than 10%, then that nozzle should be replaced. If necessary, replace all nozzles on the boom to achieve an even spray. Replace nozzles giving broken or uneven spray patterns. Note: Pressure is normally read from a gauge near the pressure regulator, some distance from the nozzle and consequently there may be a pressure loss between these two points. It is a good idea to periodically check the pressure at the nozzle. Hypro recommends that periodical checking of your boom sprayer is carried out by at an AEA or NSTS approved Sprayer Test Station.

Overall spraying:

(a) Check sprayer speed. This is vital for accurate spraying as wheel slippage can make speedometer readings inaccurate.

(b) Measure off a 60 metre (200 ft) strip down the edge of a field and mark this length permanently by using e.g. painted fence posts.

(c) Start far enough behind the first post to reach the desired speed before you pass it. Note the time it takes you to then reach the second post.

(d) Calculate your actual speed in kmph or mph.

(e) Select the correct type of spray tip using the recommendations on the chemical label.

(f) Select correct spray tip capacity the operating pressure required at the tip considering the effects of spraying pressure on droplet size, spray angle and coverage.  Or: If the desired speed is not shown or your nozzle spacing is different from the 50cm (20 inches) on which most application rate tables are based

(g) Before spraying, check the system for blockages, leaks, kinked pipework, etc, and the spray tips for damage or wear.

Before winter, remember the system should be flushed through with clean water. All caps, nozzles, and filters should be removed and cleaned for storage. Ensure that no liquid is trapped in the system, as this may freeze.

Flat fan nozzles:

The fans from alternate nozzles should meet just above the target, whether the target is the ground, top of the crop or top of the weeds – whichever is the highest at the time of spray application.

Cone spray nozzles:

Designed to have no overlap, the patterns produced by SwirlTip and HollowTip nozzles should not touch.

To make sure that chemical will be applied evenly over the field, it is necessary to mark-out the field using tramlines, bout marker or flags.

(a) Tramlines must match the spray boom – remember that nozzles can be blanked-off to reduce boom width

(b) Foam or bout markers are very useful for pre-emergent sprays

(c) Flags and permanent markers must be made at right angles to the direction of travel.