Spray nozzles and preparing your sprayer

what do tractor sprayers usually have?

folding ‘boom’s’

what do folding ‘boom’s’ house?

multiple nozzles to release the spray mix across the length of the boom.

can nozzles be replaced?

yes

what type of nozzles are there?

specialised and multipurpose ones.

what influences nozzle choice?

product used and the context of the work

what 3 things do the nozzles dictate?

1. how much spray is applied,

2. the size of the average liquid droplet,

3. the pattern of liquid that’s spread onto sprayed area.

how are crop sprayer nozzles standardised and colour coded in the UK?

Based on flow rate

what is flow rate measured in?

litres per minute

On a nozzle it says ‘Hypro’ and F110/0.6/3 and is green

what does it mean?

Hypro = manufacturer/brand,

F = flat fan (nozzle design),

110 = angle of spray,

0.6 (and green colour) = flow rate at bar 3,

3 = recommended flow rate (bar)

what is droplet size defined by?

volume median diameter (VMD) which is the median droplet size

How will droplet size differ?

half the droplet will be smaller and half will be larger.

what happens when droplet size increases?

their numbers also increase

what’s the size of a fine spray nozzle?

150 - 200 micrometres

what’s the size of medium spray nozzles?

200 - 300 micrometres

what’s the size of course spray nozzles?

300 - 400 mircometres

As spray quality increases (very fine to very coarse) what happens to…

• VDM droplet size?

• Nozzle size?

• Sprayer operating pressure?

• Retention of spray on leaf surface?

• Risk of spray drift?

• Ability of spray to reach underleaf?

• Ability of spray to penetrate upright crop?

• decreases,

• decreases,

• increases,

• increases,

• increases,

• increases,

• decreases.

what is the most common nozzle on boom sprayers?

Flat fan spray

how does droplet size differ in hollow cone nozzles?

median droplets (VDM) are smaller than other nozzles of similar size.

why do nozzles overlap?

to ensure even spread across the width of the sprayer.

what changes can be made to the nozzles that affect spray width?

changing the height and angle of the nozzle.

when is the risk of drift higher?

when the nozzles are at a greater height

can you change the width of the nozzles?

no, they are fixed

what’s the standard width between individual nozzles in the UK and many other places?

0.5 metres

when the nozzle is at 110 degree angle, what is the working height of the nozzle above the crop?

0.5m

when the nozzle is at 80 degrees, what is the working height of the nozzle above the crop?

0.75m

who can see and control the pressure of the liquid in the sprayer?

the operator

what is the unit used to measure and define sprayer pressure?

bar

what is the usual range for ‘Bar’?

1 to 5

what does higher pressure mean for the flow rate?

higher pressure = higher nozzle flow rate

what does higher pressure mean for the quality and droplet size of the spray?

lower spray quality with more smaller droplets

what are the benefits of a faster sprayer speed?

• can be more productive - cover more area in a given time, potentially lowering labour and running costs.

• can reduce spray penetration of upright / dense crop canopies.

what are the problems with faster sprayer speeds?

• sprayer can be less stable, especially on rough ground and slopes,

• can increase spray drift - more boom instability and higher air turbulance.

what is the typical spraying speed rates?

8-12 km/hour

How do the benefits and problems of fast spraying differ from that of slow spraying?

it’s the opposite

what does droplet size interact with?

windspeed,

spray height,

tractor speed,

any other meteorological factors (humidity)

what do air induction nozzles do?

mix air into droplets which makes them bigger and less likely to drift

what are the difficulties with air induction nozzles?

they are especially hollow and explode on impact to get better spray spread on the plant material.

what is sprayer calibration?

setting up the sprayer to apply the correct amount of product per unit of area

what will the amount of mixed product applied to a specific area of land be determined by?

• forward speed,

• sprayer operating pressure,

• nozzle flow rate,

• spacing between nozzles.

what will the amount of pesticide applied to a specific area be determined by?

the amount of pesticide product per unit of water in the sprayer tank

what doesn’t the product label tell you and why?

how much water and product you need in the tank for any given field

Because… this will be determined by the size of the area to treat.

what will the product label tell you?

what rate you can/should apply in terms of litres of their product per hectare, whilst many will also dictate/guide nozzle flow rates

what price of information isn’t needed for calibration?

the width of the sprayer

what information is needed to be measured when calibrating a sprayer?

measure the slow rate if the nozzles at the engine revs and sprayer pressure levels you intend to use when spraying.

How can you measure the flow rate?

use a measuring jug and measure the output of individual nozzles for 60 seconds

what other piece of information is needed when calibrating a sprayer?

tractor speed

What is the standard way of measuring tractor speed?

1. select gear and engine revs you will use to spray,

2. mark out a distance of 100 metres in similar terrain to where you’ll be spraying.

3. measure the time in seconds it takes the tractor to travel the 100m distance.

4. speed = 360 divided by the time in seconds it takes the tractor to travel 100m.