This page helps you read the chart and document your selection. The linked guide is an industry technical reference, with a reproduced HGCA/AHDB selection poster; the actual manufacturer's catalogue supplies the final nozzle specifications. AHDB research distinguishes smaller-droplet and larger-droplet air-induction nozzles, so “air induction” alone does not identify the spray quality.
Gather the inputs before opening a chart
Start a worksheet with the nozzle maker, complete tip reference, pressure unit, intended application volume, travel speed and spacing. Leave an input empty until you have established its value. Record whether a measurement came from the machine, a catalogue or an intended setting; these are different kinds of information.
Read the product instructions for the actual application. The Voluntary Initiative begins its selection sequence with the product label and then considers volume, speed, spray quality and flow. HSE's register guide explains how to find a product by MAPP number and inspect its authorisation documents.
Keep the intended crop, target and treatment reference beside the worksheet. This makes a later nozzle change understandable: another operator can see which application the original selection concerned. Avoid a note consisting only of a colour, because it leaves the manufacturer and nozzle design unidentified.
Understand what each column answers
| Chart entry | Question to resolve |
|---|---|
| Tip reference | Which exact nozzle does this row describe? |
| Pressure | At which setting is its stated output measured? |
| Flow in L/min | How much liquid leaves an individual nozzle? |
| Travel speed | Which speed is used to obtain the area-based volume? |
| Application volume in L/ha | How much spray liquid is delivered over the treated area? |
| Spray quality | What droplet classification accompanies that operating point? |
Use this table as a reading checklist, rather than a substitute manufacturer's chart. In particular, find the pressure and speed column headings before comparing two outputs. The guide explains that not every combination of flow and spray quality can be achieved with conventional pressure nozzles, and directs users to manufacturer literature for final selection.
A downloaded chart belongs with its publication details. Save the edition or document date, identify the machine on which you used it, and distinguish a new nozzle's nominal performance from an installed nozzle's measured output.
Calculate the required output per nozzle
The metric formula in the technical guide is:
L/min per nozzle = L/ha × km/h × nozzle spacing in metres ÷ 600.
Invented arithmetic example, not application advice: suppose a worksheet uses 180 L/ha, 8 km/h and 0.5 m spacing. The required output is 180 × 8 × 0.5 ÷ 600 = 1.2 L/min per nozzle. These deliberately invented inputs do not establish an authorised rate, suitable spray quality or acceptable machine speed.
Locate that output in the relevant nozzle catalogue and read the associated pressure and quality information. Do not treat the calculated answer as permission to increase pressure until any available tip produces it. If the chosen operating point is unsuitable, revisit the selection with the equipment instructions and application requirements.
Write the calculation with its units rather than recording “1.2” alone. Keep spray-liquid volume separate from pesticide dose. The tank mix calculator handles area-based liquid and product totals after the application inputs have been established.
Check output on the installed machine
The industry guide tells operators to check that boom nozzles match in size, type and angle, inspect patterns and compare jug-test outputs with manufacturer data. AHDB's handheld calibration explanation likewise measures plain-water output at normal operating pressure to obtain litres per minute.
For your calibration record, create columns for nozzle position, tip identification, test pressure, collection duration and collected quantity. Record the original observations before calculating a flow. If different people collect measurements, agree which timer and container are being used and how a partially filled graduation is read.
Keep a problem nozzle identifiable throughout maintenance. A useful workshop note describes the symptom, action and repeat measurement. Avoid overwriting the first result with the corrected result: preserving both makes the repair understandable and lets the reviewer distinguish a blocked tip from an inaccurate transcription.
Keep your spray records in one place. Free to start.
The guide recommends a brush for cleaning blocked or partly blocked nozzles and replacement when they cannot be cleared. It also calls for damaged spray patterns to be addressed. Follow the equipment's own maintenance instructions for handling the components and conducting the check.
Separate flow, droplets and drift recognition
A flow chart, spray-quality description and formally recognised drift rating answer separate questions. The industry guide discusses nozzle output and quality, while AHDB's research shows why broad design labels do not describe every air-induction nozzle equally.
Keep the complete tip and operating-point reference in the equipment record. When a job involves a buffer assessment, carry that reference into the LERAP guide, together with the product's actual conditions. Do not infer a recognised rating solely from the nozzle's colour or the phrase “low drift”.
If the chart appears to disagree with the controller, record both values and their units. Confirm whether one is per nozzle and the other for the complete boom. Check that the speed and nozzle spacing entered into the calculation match the machine configuration. These are worksheet checks; they do not replace diagnosis by the equipment supplier.
Common chart-reading problems
The chart gives gallons per acre. Select the manufacturer's metric version for this workflow. Do not combine a gallons-per-acre rate with the metric equation above. Keep the original units visible if you ask the supplier to explain a conversion.
The measured flow differs from the printed value. Compare identical pressure and tip references, retain the measured output and follow the maintenance procedure. The guide specifically calls for checking measured output against manufacturer data.
The nozzle colour looks right but the row is missing. Identify the full model designation. Ask the manufacturer for the matching table rather than substituting the nearest-looking design. Keep the response with the equipment's calibration information.
The operating settings changed during the job. Record the final configuration and the treatment affected. A nozzle selection worksheet describes a particular arrangement; mark a superseded worksheet clearly so the next operator does not mistake it for the current setup.
Connect the calibration to the spray record
Use a shared equipment name in the workshop log and the treatment diary. Include the calibration reference, actual treatment date and any change of tip or pressure that needs explaining. Preserve the original chart separately so a reader can retrace how the selection was made.
Use the treatment record to connect the completed operation with its equipment notes; the manufacturer's chart and product authorisation remain the sources for their respective specifications. For the application entry itself, continue with the spray record form.
Build a comparison sheet for replacement tips
For a replacement decision, put the original and proposed tip on separate rows. Identify the supplier, catalogue edition, nozzle material, spray angle and stated operating range. Keep a column for the spray quality at the intended operating point rather than treating quality as a permanent property of every pressure setting. The industry guide discusses both pressure-dependent quality and limitations on combinations of output and spray quality.
Add the measured output of the installed tips as observations, with the test conditions visible. Keep a faulty tip's position in the record so workshop staff can distinguish a repeated fault at one location from a problem affecting the entire set. Ask the supplier to explain a specification that cannot be reconciled with the markings on the component.
After fitting replacements, label the earlier comparison sheet as superseded and retain the new calibration reference. Make a concise handover note identifying which set is installed, which components were removed and where the supporting catalogue is filed. This proposed worksheet is for equipment administration: it does not confer a drift rating, establish chemical compatibility or supply an authorised use condition.
A measured-output comparison is especially useful when a controller setting and a paper chart appear inconsistent. Keep raw collection measurements accessible; a rounded answer alone conceals whether an error arose in timing, transcription or unit conversion.