agricultural backpack spraying manual

agricultural backpack spraying manual
AGRICULTURAL
BACKPACK
SPRAYING MANUAL
sustainable agriculture
AGRICULTURAL BACKPACK
SPRAYING MANUAL
A Bayer CropScience Guide for Applicators
in Agricultural Crop Protection
Bayer CropScience AG
Alfred-Nobel-Str. 50
40789 Monheim
Germany
www.bayercropscience.com
2015
Mention of a trademark or brand name, a seller or proprietary product in this document is for identification
and illustration only, and does not constitute an endorsement, guarantee, or product warranty by Bayer
CropScience and does not imply a criticism nor exclude any other alternative product that may be available &
suitable for use.
CONTENTS
Bayer provides this manual as a guideline for professional use on plantations,
farms and smallholdings, for both covered and open-field crops. It does not
cover the use of Backpack sprayers for amenity land, horticulture, forestry,
vector control or domestic pest control.
1.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
2.
2.1.
2.2.
2.3.
2.4.
2.5.
2.6.
2.7.
2.8.
2.9.
Backpack Sprayers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Types of Sprayers and Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Uses and Benefits of a Backpack Sprayer . . . . . . . . . . . . . . . . . . . . . . . . 12
Buying a Backpack Sprayer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Parts of a Backpack Sprayer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Useful Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Types of Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Selecting Suitable Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Sprayer Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Problem Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.
3.1.
3.2.
Personal Protective Equipment (PPE) . . . . . . . . . . . . . . . . . . . . . . . . . .44
Choosing appropriate PPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Personal Hygiene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.
4.1.
4.2.
4.3.
4.4.
4.5.
Calibration and Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Spray quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Sprayer calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Product amount calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Spray Mixture Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Application – Good Spraying Practice . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.
5.1.
5.2.
5.3.
5.4.
Using Pesticides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Pesticide Legislation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Hazard Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Product Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
First Aid in Case of Accidents (Emergency Procedures) . . . . . . . . . . . . . . . . . . 76
6.
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
7.
Conversion Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6|
Introduction
1. INTRODUCTION
There are many types of ground-driven and
portable sprayers used by growers to protect
their crops against insect pests, fungal and
bacterial diseases and weeds but Backpack
(or backpack) sprayers are probably the most
important and widespread type of sprayer
used worldwide in agriculture.
Introduction
|7
The main reasons for using a Backpack
sprayer are:
• TERRAIN
On land that is too steep, narrow, wet or
hard-to-reach for larger, heavier grounddriven sprayers; anywhere a man can walk.
• COSTS
Backpack sprayers are less expensive and
have lower maintenance costs than grounddriven sprayers.
• ACCESSORIES
A range of tools are available, increasing the
scope of applications and making Backpacks
both useful and versatile as well contributing
to improving spraying efficiency.
• CONVENIENCE
Areas to be treated are relatively small.
Backpack sprayers have been in use for over 100 years and the first reports of a Lever Operated
Backpack Sprayer (an LOK sprayer) show it was used on a large-scale to apply fungicides in
vineyards in France in the late 1880s. Sprayers in those days were very heavy and cumbersome.
However, innovative designs and the availability of lighter-weight, more durable materials has
substantially improved the Backpack over time! Hundreds of manufacturers worldwide now produce Backpack sprayers and they are made from a range of metal and plastic materials in many
different shapes, colours and sizes. Nevertheless, the basic components and the requirements
for their use are the same for all types. A good quality Backpack sprayer should be safe, reliable
and capable of being used repeatedly and effectively under field conditions.
Sprayers should have the following features:
Types of ground-driven crop sprayers and a Backpack sprayer (left)
Backpack sprayers are extremely versatile tools and are often the most appropriate
sprayer for jobs in most parts of the world. They have numerous advantages and are
considered ideal for spraying small or larger areas of agricultural and horticultural
field and tree crops. They can be used in field crops for application volumes of
100 – 500 l/ha or in tree crops where 600 – 1000 l/ha may be required.
• Robust and lightweight – not more than
25 kg when filled with spray solution
• Ergonomic design (comfortable, spreads the
load between the back and shoulders)
• A wide range of accessories
• A limited number of parts subject to wear,
requiring maintenance / replacement
• Durable – low cost to maintain the sprayer in
good working condition
• Repairable – all parts readily available and
easily changed
• Possible to calibrate
8|
Backpack sprayers
Backpack sprayers
|9
2. BACKPACK SPRAYERS
2.1 Types of Sprayers and Pumps
The four most common
types are:
Portable sprayers are either of the small, handheld, compression type (1 – 10 litres); larger, lever
operated Backpack sprayers (12 – 20 litres) or ground, wheeled sprayers, often referred to as trolley
sprayers (18 – 120 litres).
Handheld (Compression)
Backpack (Lever pump)
Trolley / Wheelbarrow (Motorized)
• COMPRESSION SPRAYERS
Uses a hand operated pump, which is part of
the lid to create the pressure in the airspace
above the spray liquid in the tank. During
spraying, the tank pressure falls and must be
recharged frequently to maintain pressure.
• LEVER OPERATED SPRAYERS
Backpack sprayers where the operating
pressure is maintained by the operator
using regular lever stokes at around
10 strokes / minute.
Types of standard portable sprayers
There are other specialist types of sprayers, less frequently used for crop spraying, such as
thermal or cold foggers and spinning disc (rotary atomizer) sprayers used for controlled droplet
application CDA.
Thermal fogger
Cold fogger
Compression pump
Lever Backpack
Spinning disc
Motorized Backpack
Modern Backpack sprayers are manufactured from robust materials which allow easy maintenance
and are basically all either metal (stainless steel or brass) or rigid, injection molded plastics.
With a net weight in the range of 3 – 5 kg when empty, compression sprayers are relatively lighter
than powered sprayers which are mostly in the 6 – 12 kg range.
The Backpack sprayers most commonly used for spraying crop protection chemicals are either
manually operated, using a pumping lever, or are motorized.
Motorized mistblower
• MOTORIZED BACKPACK
Using a two-stroke petrol (gasoline) engine
or a 12V rechargeable battery to provide
power instead of manually pumping.
• MOTORIZED MISTBLOWER
An air-assisted sprayer using a larger twostroke petrol engine to drive a pump and
centrifugal fan that produces a high speed
airstream to provide very fine misting spray
droplets which must be directed towards the
target crop from the flexible, discharge hose
and the spray can reach up to 13 m from the
hose to the target crop.
10 |
Backpack sprayers
When considering lever-operated and motorized sprayers,
the advantage for lever-operated sprayers is that they are
less expensive and lighter weight than heavier motorized
sprayers, which of course do not require any lever operation.
Backpack mistblowers are heavier so make sure that the
backrest and shoulder straps are padded and comfortable
when the sprayer is worn.
Concerning the motorized types of sprayers, an advantage
for petrol engines is that they have become much more reliable, easier to start and they run well, whilst the disadvantage of batteries is that they discharge and may need to be
replaced during spraying.
Motorized mistblowers are particularly suitable for large areas
and high crops in orchards, vineyards and all plantation tree
crops such as rubber, mangoes and bananas. They are also
often used in greenhouse crops. The blower produces a very
fine spray of about 100 microns, discharged at high-speed
up to a distance of about 10 – 14 m and with a swath width
of 3 – 6 m. The larger size of their motor makes them heavier
(10 – 12 kg empty) than motorized Backpack sprayers (7 kg).
Backpack sprayers
Petrol engine
| 11
A comparison of the features of motorized Backpack sprayers and motorized mistblowers is
shown in this table.
Motorized Backpack
Motorized mistblower
Higher capital and maintenance costs than
lever-operated
Much higher capital cost (x10) and maintenance costs
than lever-operated sprayers
Manual pumping not required
Manual pumping not required
Powered by petrol motor or 12V battery
Powered by two-stroke petrol engine
Commonly used in agriculture for many purposes
Specialist use in agriculture in plantations, vineyards,
high crops and greenhouse crops
Short distance hozizontal spraying range, 1 – 2 m
Horizontal spray range 12 – 15 m, vertically (tree crops)
up to 10 m
Spray output (l/min) managed by nozzle size
and pressure
Spray output (l/min) adjusted by a variable or fixed
restrictor on the lance or nozzle
Can treat a smaller crop area (ha/hour) than a motorized
mistblower
Can treat a bigger crop area (ha/hour) than a
motorized Backpack sprayer
Cannot be used to apply dust products
Can easily be converted to apply dust products
Lighter net weight (6 – 8 kg) than motorized mistblowers
Heavier net weight (10 – 12 kg) than motorized
Backpack sprayers
Can apply all droplet size spray categories
Can only apply fine / very fine droplets
Spray tank range 10 – 20 litres
Spray tank range limited to 10 – 16 l due to weight
Battery engine
The sprayer types, their normal tank volume range and their main agricultural uses are shown
below, highlighting the four types of Backpack sprayers. The droplet size range they produce
depends greatly on the chosen nozzle size and pressure.
Motorized Backpack
Motorized mistblower
Higher capital and maintenance costs lever operated
sprayers
Much higher capital cost (x10) and maintenance costs
than lever operated sprayers
Manual pumping not required
Manual pumping not required
Power is petrol driven motor or 12V battery
Powered by 2 stroke petrol engine
Commonly used in agriculture for many purposes
Specialist use in agriculture in plantations, vineyards,
high crops and glasshouse crops
Short distance hozizontal spraying range, 1 – 2 m
Horizontal spray range 12 – 15 m, vertically (tree crops)
up to 10 m
Spray output (l/min) managed by nozzle size
and pressure
Spray output (l/min) adjusted by a variable or fixed
restrictor on the lance or nozzle
Can treat a lower crop area (ha/hour) than a motorized
mistblower
Can treat a higher crop area (ha/hour) than a
motorized Backpack sprayer
Cannot be used to apply dust products
Can easily be converted to apply dust products
12 |
Backpack sprayers
Backpack sprayers
2.2. Uses and Benefits of a Backpack Sprayer
| 13
2.3. Buying a Backpack Sprayer
Using a Backpack sprayer is an economical and manageable way of spraying field crops, particularly where a ground
trailed or motorized boom sprayer is not available and may
not be appropriate for the job. They are the ideal equipment
for spraying smaller crop areas or where land is inaccessible
to mechanized sprayers. When they are properly calibrated
and maintained, they can provide a long and useful service
life and permit accurate spraying and successful crop protection. Under most field crop situations, it is usually possible
to cover about 0.8 – 2.0 ha per working day.
Reliable dealers should readily
provide manufacturer specifications for a sprayer. Please also
review technical information and
look for additional information
on websites before buying.
Maintaining a constant, uniform working pressure in a
Backpack sprayer is very important. Pressure regulation
can only be achieved when the sprayer is properly calibrated.
Some sprayers have built-in valves in the spray tank to
regulate pressure and others have pressure gauges on
the handle. Both types are very useful as long as uniform
pressure can be maintained while spraying.
One of the first decisions to be made is to select and buy a sprayer with a lightweight tank to
reduce the overall weight and to choose the correct tank size for routine spray jobs.
Secondly, can the sprayer be set up to maintain the working pressure needed to keep the
nozzle output at the correct spray volume with ease of operation so that the crop can be
sprayed effectively? Sprayers should also permit calibration.
The sprayer should be of a simple and
reliable design, of robust construction,
made of strong materials and easy to fill,
use, clean and maintain. It is also important to select a sprayer that is free from
all leaks when all the parts are properly
connected and tightened. Leaking from
Types of standard portable sprayers
the tank lid, hoses, trigger and shut-off
valves is one of the most common issues
for Backpack sprayers. Avoiding leaks is
vital to prevent operator exposure to crop
protection products.
14 |
Backpack sprayers
Backpack sprayers
Look at the choice of sprayers that are available locally and give priority to choosing a
sprayer that feels comfortable and balances
well when worn.
| 15
Comfortable frame and straps
It will need to have a good quality frame and
strong shoulder straps, at least 30 mm wide.
to reduce fatigue when carrying a heavy load
whilst walking and spraying. Don’t forget that
a fully loaded Backpack sprayer may weigh as
much as 20 kg!
The filling opening on top should be large and
make it easy to fill the tank without spilling.
The cap should be tight-fitting and leak-proof
to prevent spray liquid from spilling on the user
or the ground. The cap on a mist blower must
also be airtight. The sprayer should be able to
stand firmly on the ground when removed to
avoid any chance of spilling the tank load of
spray mixture.
The wand and hand grip should be comfortable
and easily removable to clean. The pumping
lever should also be in a comfortable position.
A well-designed pumping lever will reduce arm
and shoulder fatigue whilst using the sprayer.
Consider buying a sprayer with a reversible
lever that can accomodate both right- and lefthanded users. The lever must be at a comfortable level for smooth operation, which will be
in the range of about 8 – 10 strokes / minute.
Sprayers with large, easy to fill openings
Sprayer with pumping lever fitted for right and left hand action
Local suppliers should be able to give guidance
on selecting the right sprayer and the availability of spare parts at a reliable price. Sprayers
must be maintained in proper working order.
right
left
16 |
Backpack sprayers
Backpack sprayers
2.4. Parts of a Backpack Sprayer
Although Backpack sprayers may look very different in design, size, shape, colour and materials,
the key components of all sprayers are basically the same. A standard Backpack sprayer can
have as many as 80 parts. When describing sprayers, there are often several different names for
the same sprayer part, as indicated in the following section.
1. Chemical tank
2. Strainer
3. Tank lid
4. Plastic packing & nut
carrying and
Keyoperation.
parts of a Backpack sprayer
Nozzle
Lance
Pump
Connecting
hose
Filling cap
Spray
release
trigger
Tank
Pumping
lever
Storage tank
5. Chassis
6. Pumping lever
Tanks come in many different shapes, colours
and sizes. The storage tank, fitted with a fill
cap, is an ergonomically designed container
for liquids which should be durable and resistant to impact, even if the sprayer is dropped
onto a hard surface. The tank holds and
supplies the spray liquid. Generally, the tank
should have a capacity of 15 – 20 litres. They
should have clear graduation marks on the
side for easily measuring spray liquid volumes
7. Piston assembly with filter
8. Cylinder
9. Agitator
10. Compression chamber assembly
11. Pumping shaft
12. Feeding tube
13. Hose with connectors
14. Discharge valve assembly
with filter
15. Discharge lever
16. Spray lance
17. Lance filter
18. Adjustable spray tip
19. Spray tip nut
20. Carrying, shoulder straps
Key parts of a Backpack sprayer (lower)
The basic components of a Backpack sprayer
are similar to that of a field boom sprayer.
Firstly, the sprayer has a storage tank for
holding the spray liquid and this is connected
to a pump. Often the pump is manually
The pump is connected to the pressure
chamber with a one-way valve and then
to the connecting hose, which ends in
the spray lance (or wand). An interchangeable nozzle (nozzle set) at the end of the
lance discharges and controls the triggerrelease spray of droplets. The sprayer must
be adequately fitted with filters (also called
screens or strainers) at three points to
prevent the solid particles in the liquid from
clogging the spray. The tank is fitted onto a
back frame or shoulder straps to facilitate
| 17
operated with muscle power using a pumping
lever (or handle, hand grip), but a sprayer
can also be motorized, operated by a twostroke engine or rechargeable battery.
in the tank. It is not very common, but they are
sometimes fitted with an agitator to maintain
the spray in solution or suspension. If not,
then the sprayer may need to be shaken lightly
before spraying to agitate the spray mixture.
Some sprayers have a tank that is also fitted
with a pressure release valve that activates
automatically when the tank pressure exceeds
the target pressure.
18 |
Backpack sprayers
Backpack sprayers
Pumps and pumping lever
Lever-operated Backpack sprayers have either a piston or diaphragm pump inside a pressure
chamber in the tank to pressurize and deliver the spray liquid to the nozzle(s). The tank itself is
not pressurized. The spray liquid is drawn through a valve into a pump chamber and then pressure chamber by the lever strokes. The air compressed in the pressure chamber forces the spray
liquid on through the hose to the nozzle. Both types can maintain a constant pressure whilst
spraying and the two types compare as follows:
•P
ISTON PUMP
A piston pump is generally capable of developing higher working pressures of around
6 bar and can produce a high nozzle pressure
of up to 5 bar but, although they are easier
to clean, they have a higher wear rate.
Piston pumps are most frequently mounted
internally but occasionally they are externally
mounted. The advantage of internal mounting is that the pump tends to be larger and
requires less physical work with the lever.
They are therefore more efficient and any
leakage or spillage from a sprayer with an
external pump could contaminate the operator with the crop protection product.
•D
IAPHRAGM PUMP
Diaphragm pumps have a flexible elastomer
diaphragm but, although they can achieve an
operating pressure of around 5 bar, nozzle
pressure reaches only 1 – 3 bar, making them
seem less efficient. They are mechanically
simpler in construction, which means they are
more resistant to wear and require less maintenance. They produce more spray volume / lever stroke than piston pumps. All motorized
backpack sprayers have diaphragm pumps.
| 19
Both types of pumps are connected in a similar way to the pumping lever. The lever is mounted
on the side of the sprayer and is often reversible allowing it be mounted for either left- or righthanded operation.
Compression
Piston
Piston (external)
Diaphragm
Lance and trigger
A spray lance is designed to keep a distance between the spray and the operator for safety
reasons. A typical lance (or wand) is at least 50 cm long, either of fixed length or telescopic and
fitted with a positive on / off valve as the trigger (or control valve handle). The trigger is used to
precisely control the pressure and spray application. The lance is connected at one end to a
durable hose with a radius of at least 5 cm, which must be long enough so that is not flattened
when bent through 180°. All connections should be able to be adjusted and tightened by hand –
using protective gloves if the sprayer is filled with spray mixture! The nozzle assembly is attached
to the other end of the lance. Sometimes the trigger may be factory fitted with one of several
types of pressure regulators, or on some sprayers a pressure regulator can be fitted as an
accessory using a tee-joint.
Complete handle
Details of a handle and trigger
Trigger valve
Nozzle
assembly
Lance
Lance filter
Trigger valve
Spindle and
on / off seals
Hand grip
20 | Backpack sprayers
Backpack sprayers
Pressure regulation and monitoring
Manual Backpack sprayers are operated at
moderately low pressures in the range of 3 – 6 bar
and most sprayers have only one spray control –
the on / off switch which serves as a trigger. This
offers very little control for maintaining constant
pressure whilst spraying and ensuring that the
nozzle is delivering the correct flow rate and
amount of spray. There are three types of pressure devices that can be fitted to sprayers:
• Pressure relief valves –
controlling pressure
• Pressure control valves –
regulating pressure
• Pressure gauges –
monitoring pressure
Some sprayers, particularly compression
sprayers, have factory built-in adjustable
(low / high or 1 – 4 bar settings) PRESSURE
RELIEF VALVES fitted inside or outside the
tank which allow excess pressure built up in
the tank to be released. However, they do not
help regulate pressure in the nozzle.
the upstroke, the down-stroke and as the
operator tires, making pressure maintenance
less accurate.
PRESSURE CONTROL VALVES
Pressure control valves are a means to overcome these pressure fluctuations. There are
many types designed specifically for Backpack sprayers and if they are not factory fitted,
there are many available that can be installed
as an accessory on most sprayers. Automatic pressure control valves are attached in
the lance, usually directly before the nozzle,
providing optimal and improved spray regulation. They open when their required pressure
is reached, lowering excess pressure back to
the pre-set pressure and closing again when
pressure drops below the required pressure,
shutting-off the flow to the nozzle.
Most pressure control valves are colour coded
for the pressure they maintain such as Constant
Flow CF valves with yellow (1 bar), red (1.5 bar),
blue (2 bar) and green (3 bar).
Constant pressure is important for accurate
and uniform spraying but it is difficult to maintain during spraying because of the fluctuations in pressure while pumping the lever on
Valve with high / low settings
CF Constant flow valves: 2 bar (blue); 1.5 bar (red)
CF valves are chosen according to the type of
spray application and the crop being sprayed.
They are very reliable, maintaining constant
pressure, and their use makes the calibration
of spray output more precise. Only the yellow
and red valves are recommended for most
Backpack sprayer applications but sometimes
the blue is used so as to be able to work at
higher (2 bar) pressures.
PRESSURE GAUGES
Pressure gauges can be fitted to the spray
lance to monitor actual pressure but they do
not control pressure. However, they can help
the spray operator to adjust and regulate pressure, thereby ensuring a more uniform application. Gauges vary in cost and price is usually
a good indication of accuracy.
Mistblowers do not rely on pressure to maintain flowrates but instead use velocity and
air volume to control flowrate. The fan has to
be run at high speed to maintain the correct
droplet size and crop coverage.
| 21
CF Constant flow valves – colour coded:
1 bar (yellow) ; 1.5 bar (red)
Various types of flow rate regulators
Pressure gauge fitted
to a trigger
Flow rate regulator with
pressure gauge
22 | Backpack sprayers
Backpack sprayers | 23
Filters
Although water used for spraying must be clean, the water source may contain solid particles of
soil, grit or sand. Also, all types of formulations of products may contain undispersed solid particles which can also build up as residues in the sprayer. The filtration system is therefore very
important to avoid blocking nozzles and consists of three types of filters which progressively
remove larger to smaller solid particles along the line according to their screen or mesh size:
• B asket filters – are the largest type and provide coarse filtration (ca. 30 mesh/inch) fitted
in the neck of the tank to filter only while the
tank is being filled
• L ance filters – are long and fit in the handgrip of the lance, providing medium filtration
(ca. 50 mesh/inch) when the spray is released
• Nozzle filters – are small and either the cup
or cylindrical (“top hat”) type which includes
slotted strainers and check valves, fitted into
the nozzle body inwards from of the spray
tips. They provide fine filtration (ca. 50 – 100
mesh/inch) to prevent clogging of the spray
tip and to ensure that the correct spray pattern is delivered. Nozzle filters are sometimes colour coded for mesh size. The mesh
size must be smaller than the nozzle orifice
size to prevent solid particles reaching and
blocking the nozzle.
Location of the Nozzle, Basket and Lance filters
Back frame / shoulder
and waist straps
Location of the Nozzle, Basket and Lance filters
Whether the sprayer is fitted into a back frame
(or harness) or not, it must have adjustable, padded, shoulder straps and will be even more
comfortable to carry if it also has waist straps
with a belt and buckle to secure the sprayer on
the user’s back. If the sprayer is not factoryfitted with a back frame, it may be possible to fit
one as an accessory.
Nozzle filter
Cup
Cylinder
Check valve
ca. 50 – 100 mesh
in front of
the spray tip
Basket filter
ca. 30 mesh
in neck of
spray tank
Lance filter
ca. 50 mesh
in the hand grip
(trigger)
Spare parts
It is very useful to keep a set of spare parts
especially for those that need more regular
replacement such as nozzles, O-rings, filters
and the screws and washers necessary to be
able to make a quick repair without having to
return to suppliers for the parts. Most manufacturers provide spare parts lists and kits of
spares can be bought that cover most of the
most common replacements and repairs that
will be necessary during spray operations.
Spare part kite
24 | Backpack sprayers
Backpack sprayers | 25
2.5. Useful Accessories
Spray booms
The range of attachments for Backpack sprayers has also become quite extensive and widely
available in recent years. Pressure regulators and control valves have been discussed above
(in section 2.4) and a range of lances and telescopic extensions for applications in high crops are
important. Various types of spray booms and herbicide spray shields are also available. The
range of various types of non-drip and drift-reducing nozzles is always increasing and
becoming more widespread.
Booms are available in several configurations but most often they are fitted with 2, 3 or 4 nozzles
spaced along the boom at 50 cm intervals. They are not as commonly used for crop spraying as
a standard spray lance.
Lances, extended lances
Three different types of lances can be used for
Backpack spraying. They are made either from
brass or different types of plastic. Both materials
are equally good as long as the lance is strong
and sturdy:
•S
tandard – provided with the sprayer or
bought as spare parts for different spray
operations; normally 0.37–2.0 m in length
•E
xtensions – to extend the length and
range when attached to the standard lance;
normally 0.5 – 1.0 m in length
•T
elescopic – variable length lances for
high, tree crop spraying; normally 0.5–3.6 m
in length
There is a choice of spray elbows that can be
used on the end of the lance for the nozzle
assembly. They vary in their angle from
straight to right-angle (90°) and, in addition
to the normal single elbows, twin elbows are
also available and usually used for spraying at
higher volumes with a fine spray or to increase
penetration into the crop.
Double spray elbow
Double and single nozzle holder
Examples of standard lance, telescopic and extension lances
They are carried horizontally to spray sideways
across several crop rows, widening the area that
can be sprayed during each pass. Bayer CropScience is developing a lightweight, five nozzle,
3 m boom that is carried by two spray operators
and operated by two Backpack sprayers. This
offers a very wide spray swath over row crops.
Spray booms can also be mounted as tail
booms to spray horizontally or vertically behind
the operator as he walks forward.
coverage in the crop. They are more commonly
used for spraying herbicides. However, the
spray technique is a little more complex and
some practice may be necessary to be able
to spray accurately. When using a hand-held,
forward-spraying boom, the flat fan nozzles
are set 50 cm apart on the boom with a spray
angle of 110° at a height of 0.6 – 0.8 m above
the crop canopy. This creates a ‘double overlap’ spray pattern.
But using a spray boom attached to your sprayer
is a very useful way to increase the spray swath
that can be sprayed during each pass through
the field. This applies particularly to spraying
crops such as cotton or soya, thus saving time
and effort and giving an improved uniform
However, the use of more than one nozzle at a
time requires more output from the pump during
spraying to maintain the required pressure and
spray volume. Booms are more suited to use
with motorized Backpack sprayers.
Booms with 2, 3 and 4 nozzles set at 50cm intervals
5 nozzle hand carried boom
3 nozzle boom set
26 | Backpack sprayers
Backpack sprayers
Herbicide shields
Herbicide shields or spray hoods are specifically used to prevent spray drift away from the target
to neighbouring plants and limit damage to other crops during herbicide application.
They are made from plastic or metal but are basically either compact, round
or wide:
•R
ound shields – used for localized band
and spot spraying of weeds between
non-target crops
• W ide shields – for inter-row spraying
especially in plantation and vineyard crops.
They are designed to be placed over the end
of the spray lance and are fitted with a flat fan
or hollow cone spray nozzle inside the hood.
The herbicide dose rates have to be calculated
for the actual area being sprayed only.
Examples of various types of spray cones used to prevent spray drift when applying herbicides
| 27
28 | Backpack sprayers
Backpack sprayers | 29
There are four major types of hydraulic nozzles
used on Backpack sprayers. No single nozzle
type is suitable for all applications. Nozzles are
defined by the spray pattern they produce:
•F
lat fan
Flat fan nozzles produce a narrow, elliptical
spray pattern. Most flat fan nozzles have a
basic spray angle of 65°, 80° or 110°. Overall,
they are the most commonly used nozzles
in crop protection and are suitable for most
uses with insecticides, fungicides and
herbicides. They can produce small to large
droplets depending upon the nozzle size and
pressure being used, normally in the range
of 2 – 4 bar. Using larger orifice nozzles and
lower pressure will produce larger droplets
and coarser sprays. There are two different types of flat fan nozzles, Standard (or
tapered) flat fan with a narrow, oval spray
pattern where droplets are concentrated in
the centre and Even flat fan. Although both
seem very similar with a narrow, oval pattern,
even flat fan nozzles produce a uniform spray
pattern across the entire width of the spray.
Because of this even spray pattern, they are
often the most suitable nozzle for broadcast
spraying when using a Backpack sprayer.
However, the nozzles were designed for
band spraying along or between crop rows.
2.6 Types of Nozzles
Nozzles are designed to atomise spray liquids into droplets which are necessary to effectively
and evenly distribute the product on the target crop. In effect, nozzles are the front end of a
sprayer and are probably the most critical part because they affect flow rate, uniformity of
spraying, coverage and spray drift. In most cases, they are also one of the least expensive
components of the sprayer but still perform a very important role. We will take a closer look at
the components here.
In terms of definitions, the word “nozzle” can be used to describe the whole nozzle assembly
of body, filter and cap or just the nozzle body, which is also often referred to as the “tip”.
• Flood
produce a wide angle, up to 150°, flat spray
pattern, with large droplets at low pressure,
giving very even distribution with a coarse
spray quality. They are best suited for band
spraying and applying selective and total
herbicides (and fertilizers).
•H
ollow cone
produce a circular spray pattern with the
droplets concentrated on the outside of the
circle. There are two designs: core-insert
cones and disc-core cones which have a
core and a swirl / whirl plate used to create
the swirling motion required to produce the
cone shape spray. The spray droplets are
small and produce finer quality sprays. They
are generally used for foliar application of
insecticides and fungicides to field crops
when canopy penetration and good coverage is required. They are used at higher
pressure of up to 4 bar, higher than flat fan
nozzles.
•S
olid (or Full) cone
also produce a circular shaped pattern but
the spray droplets are equally distributed
across the circle. They produce smaller
droplets and are generally used for spot
applications and foliar application of insecticides and fungicides to give comprehensive coverage, especially where drift control
is required.
Types and spray pattern of the important spray nozzle tips
Standard flat fan
Even flat fan
Flood
Hollow cone
Full cone
30 | Backpack sprayers
Backpack sprayers
Nozzles are available in a wide range of metal, ceramic and plastic materials that vary in their
cost and resistance to wear during use. Ceramic nozzles are considerably more expensive but
are resistant to wear and last longer than other materials before they become worn and have to
be replaced.
For Backpack spraying, plastic and stainless steel nozzles are normally the best choice and are
therefore the preferred material.
Nozzle technology is always improving and newer types are becoming more widely available.
They are mostly designed to improve the accuracy of spraying and to reduce spray drift by
eliminating finer droplets from the spray.
Air induction (or air inclusion) nozzles
have at least one hole on the side of the body
through which air is drawn in to produce large,
air filled droplets (spray bubbles), giving a uniform, coarse spray quality and very good crop
penetration. These nozzles can make a great
contribution towards reducing spray drift,
even at high pressure, as they can reduce drift
by as much as 90% compared with standard
nozzles. Most air induction nozzles have a flat
fan pattern but they can be deflector or hollow
cone types. Some of these nozzles operate at
pressures that are not suitable for use with a
Backpack sprayer. Please ensure nozzles are
suitable for the product, water volume and
pressure as well as the crop and target.
Turbo TeeJet – a flat fan nozzle with a 110°
spray angle which has the widest pressure
range of the flat fan nozzles at 1 – 4 bar, producing larger droplets for drift reduction.
It is suitable for almost all types of application,
depending on whether high or low pressures
are chosen.
Adjustable nozzles are provided as the
standard on some Backpack sprayers. The
spray angle can be changed by rotating the
cap to produce a pattern from flat fan to a
solid stream. However, they are not recommended for most spraying since they cannot
be accurately calibrated and spray quality and
pattern are unpredictable.
Typically, a complete nozzle assembly is composed of four items: the nozzle body to hold the
screen (strainer or filter) and nozzle, a nozzle tip to regulate the spray flow and its pattern,
secured by a nozzle cap. In many cases of hollow cone nozzles, the tip consists of an orifice
disc and cone.
The spray tip plays the important role in breaking down the liquid into spray droplets. It forms the
spray pattern and then helps to propel the spray to the target crop. Tips are designed for different
spray jobs, crops, operating pressures, output angles, and spray volumes.
Finally, a note on nozzle caps: Always use round caps on a Backpack sprayer and not notched
or offset caps so that the nozzle can be rotated and aligned to the angle required for spraying.
Parts of flat fan and hollow cone nozzles (from different suppliers)
and a complete assembly
Hollow cone
(Disc-core type)
Orifice disc
Core
Cap
Washer
Screen
Nozzle body
Flat fan
Twin orifice – have two tips in one nozzle,
providing two spray patterns, spraying 30°
forward and 30° backwards at the same time
which can increase both crop coverage and
penetration. They produce small droplets
and are not usually the preferred choice for
Backpack spraying because they provide no
additional benefit.
| 31
Complete assembly
Nozzle tip
Cap
Washer
Screen
Nozzle body
Round (l) and offset (r) plastic nozzle caps
32 | Backpack sprayers
Backpack sprayers | 33
Colour coding and classification of nozzles
Nozzle manufacturers are now using their own specific colour and numbering codes for hollow
cone and deflector nozzles to clearly differentiate their nozzles and to assist customers in
making the right choice of nozzles for accurate application.
For all flat fan nozzles, regardless of manufacture, there is an international standard
(ISO 10625) that defines the flow rate of each
colour-coded nozzle. The flow rate of a nozzle
is mainly a function of the orifice size and
pressure; the lower the number of the nozzle,
the lower the flow rate.
1.51 l/minute at 3 bar. The table also shows
that, for example, decreasing the red nozzle
pressure down to 1 bar will reduce the flow rate
to 0.92 l/min and increasing the pressure up to
5 bar will increase the flow rate to 2.07 l/min.
To maintain a flow rate of 1.58 l/min but work
at a different pressure, then a grey (06) or
white (08) nozzle would be closest when reducing the pressure to 1 bar and the blue (03)
nozzle would be closest if the pressure was
increased to 5 bar. This is important when calibrating nozzles to deliver the correct flow rate.
The table below shows the ISO 10625 colours
and numbers of the nozzles. The numbers
represent the flow rate in US gallons / minute
at 3 bar so that the red nozzle (04) has a flow
rate of 0.4 US gallons / minute which is
Nozzle
Pressure
Bar
1
DT0.5
DT0.75
DT1.0
DT1.5
DT2.0
Flow
l/min
0.23
Spray
Angle
80
Litres / hectare @ Km/h
Spray
Width (m)²
0.84
2
3
81
54
4
41
5
33
2
0.32
80
0.84
115
77
58
46
3
0.39
80
0.84
141
94
71
56
1
0.34
95
1,09
94
63
47
38
2
0.48
95
1,09
133
89
66
53
3
0.59
95
1,09
163
109
81
65
1
0.46
105
1,30
105
70
52
42
2
0.64
105
1,30
148
99
74
59
3
0.79
105
1,30
182
121
91
73
1
0.68
105
1,30
157
105
79
63
2
0.97
105
1,30
223
148
111
89
3
1,18
105
1,30
273
182
136
109
1
0.91
105
1,30
210
140
105
84
2
1,29
105
1,30
297
198
148
119
3
1,58
105
1,30
364
242
182
145
01
orange
015
green
02
yellow
Pressure (Bar)
Nozzle number / color
03
04
05
blue
red
brown
Flow rate (l/minute)
06
grey
08
white
10
black
2.31
1.0
0.25
0.35
0.46
0.69
0.92
1.15
1.39
1.85
1.5
0.28
0.42
0.57
0.85
1.13
1.41
1.70
2.26
2.83
2.0
0.33
0.49
0.65
0.98
1.31
1.63
1.96
2.61
3.27
2.5
0.37
0.55
0.73
1.10
1.46
1.83
2.19
2.92
3.65
3.0
0.40
0.60
0.80
1.20
1.60
2.00
2.40
3.20
4.00
3.5
0.43
0.65
0.87
1.30
1.73
2.16
2.59
3.49
4.31
4.62
4.0
0.46
0.69
0.92
1.39
1.85
2.31
2.77
3.77
4.5
0.49
0.73
0.97
1.47
1.97
2.47
2.84
3.90
4.89
5.0
0.52
0.77
1.03
1.55
2.07
2.58
3.10
4.13
5.16
Example: A red coloured nozzle is size 04 and will deliver 1.60 l/m when sprayed at 3 bar
34 | Backpack sprayers
Backpack sprayers | 35
In addition, the nozzle also has information on the tip to identify the type and size of the nozzle and
the spray angle it produces.
Type of information available on a colour coded nozzle
a spray, which describes the spray quality category (for details see section 4.1 Spray quality).
A third nozzle classification scheme (BCPC
nozzle classification) assigns a single BCPC
code to similar nozzles from all manufacturers.
It applies only to flat fan, even flat fan, deflector
and hollow cone nozzles. The code gives the
type of nozzle, the spray angle, if known, the
flow rate and the pressure for that flow rate. A
nozzle may have the code F80/0,23/3 as shown
with other examples in the following table.
ISO
Colour-coded
nozzle
AVI
Type of nozzle
(Air induction)
110
Spray angle of 110°
The BCPC Nozzle classification codes
Nozzle type
Spray angle
Tip output
degree (if known)
Pressure
(l/min)
(bar*)
BCPC** Code
-
Flat fan (F)
80°
0.23
3
F80/0,23/3
Flat fan (F)
110°
3.2
3
F110/3,2/3
Even flat fan (FE)
80°
0.5
2
FE80/0,5/2
015
Even flat fan (FE)
80°
1.2
3
FE80/1,2/3
Nozzle size – 015
Colour-coded green
Deflector (D)
90°
0.23
1
D90/0,23/1
Deflector (D)
140°
1.85
1
D140/1,85/1
Hollow cone (HC)
85°
0.23
1
HC85/0,23/1
Hollow cone (HC)
95°
2.4
3
HC95/2,4/3
Since spray nozzles are interchangeable, keep a range of different nozzles available to match the
type of spraying needed.
Colour-coded nozzle tips with descriptions of their size (black rings) and spray angle (red rings)
*Pressure normally rated at 3 bar, sometimes at 1 bar. ** British Crop Protection Council
2.7 Selecting Suitable Nozzles
Perhaps the most difficult task to be addressed before starting to spray is to decide which nozzles to
choose for each situation to ensure that the application will be made economically and efficiently.
It is important to have the most suitable nozzle type and size to optimize the application of the
product and to have the least effect on spray drift.
Once the choice of nozzles has been made
and the flow rate is known, nozzle performance
should be monitored during spraying as nozzle
tips will wear with use until they can no longer
maintain the correct flow rate. A good rule is to
replace worn nozzles when the flow rate exceeds
the flow of a new nozzle by 10 %.
A separate colour-coding scheme (the ASABE
standard, S-572.1) is not based on the flow rate
but defines instead the droplet size range in
Selection of the correct nozzles should be based on:
• the flow rate and droplet size required from the nozzles
• whether the spraying is going to be broadcast, band
application or a spot (single plant) treatment
• whether a fungicide, herbicide or insecticide is to applied
36 | Backpack sprayers
Backpack sprayers
The following chart is a guideline on the suitability of each of the major types of nozzles depending
on the chemical application that is to be made. It also gives a general guideline on the droplet sizes,
from fine to very coarse, that are recommended for each type of application.
The best way to select the correct nozzles is to decide on the type of product to be sprayed (contact,
systemic) and the target crop. Then, based on local availability, nozzle manufacturers charts can
be used to first select the type of nozzle to use and then the correct spray angle and orifice size
to match the needed pressure, spray volume and swath (spray) width.
In general, the basic rule for the type of application is:
• Broadcast application – flat fan nozzles for a back-and-forth, waving technique
• Band application – deflector nozzles and maintain a constant height above the crop
• Spot application – solid cone nozzles, for example for young plants after transplanting
• High crop application – hollow cone or flat fan nozzles in orchards or plantations
Colour Red.
Spray pattern
Standard
Operating pressure range
Low
Type of application
Flat fan nozzles
Even flat
Flood
fan
(Deflector)
Low
Low
Airinduction
High
nozzles are kept at a constant height of 50 cm
above the crop, the spray pressure is kept at 1 bar
and the walking speed at 3.6 km/h (1 m/sec). In
this case, the nozzle selection shows what spray
width can be obtained while spraying at 200 l/ha:
Output
l/min
Width
cm
Volume Time for 15 l
l/ha
min:sec
Deflector VLV nozzles (for herbicide. very low volume)
More information on these application techniques are shown in Section 4.5. Application –
Good Spraying Practice.
Nozzle type
In the first example below, the manufacturer’s
chart shows the output for four different deflector nozzles, used for low volume spraying of
herbicides and their effect on the spray width.
Although the output changes, the spray volume
in l/ha remains the same. In the example, the
| 37
Yellow372020
0.6
50
200
25:00
Green372021
1.2
100
200
12:30
Blue372022
1.8
150
200
08:20
Red372023
2.4
200
200
06:15
Cone nozzles
Hollow
Full Cone
Cone
Moderate
High
General
droplet size
requirements
Herbicides
Pre-emergence
M
VG
VG
VG
VG
X
VG
Pre-emergence
M, C
VG
VG
G
VG
G
VG
Pre-emergence
M, C, VC
VG
VG
x
G, VG
G
VG
Insecticides
- Contact
F, M
VG
VG
G
VG
VG
VG
- Systemic
M, C
VG
VG
X
VG
G
G
VG
Fungicides
- Contact
F, M
VG
VG
G
VG
VG
- Systemic
M, C
VG
VG
X
VG
G
G
Medium
Medium
Low
Low
High
High
Risk of spray drift
Suitability: VG – Very Good; G – Good; X – Not normally suitable Droplet size: F = Fine; M = Medium; C = Coorse; VC = Very Coorse
• selecting the yellow nozzle – with a flow rate of 0.6 l/min, the spray width will be 0.5 m and spray
volume will be 200 l/ha
• selecting the green nozzle – with a flow rate of 1.2 l/min, doubling the spray output doubles the
spray width to 1.0 m, spray volume remains at 200 l/ha
• selecting the blue nozzle – with a flow rate of 1.8 l/min, the spray width will increase to 1.5 m,
spray volume remains at 200 l/ha
• selecting the red nozzle – with a flow rate of 2.4 l/min, the spray width increases
to 2.0 m, spray volume remains at 200 l/ha
38 | Backpack sprayers
Backpack sprayers | 39
A second example using another manufacturer’s chart for flood nozzles, shows the effect of changing nozzles with different spray angles while keeping the spray pressure at 1 bar. The nozzle is
held 0.5 m above the crop while walking at a speed of 2 km/h (0.5 m/s). Spray volume in l/ha then
increases with each change of nozzle. The nozzle selection shows what spray width and spray
volume will be achieved with each nozzle:
Nozzle
DT0.5
DT0.75
DT1.0
DT1.5
DT2.0
Pressure
Flow
Bar
l/min
Spray
Angle
Spray
Width (m)²
A final example from a manufacturer’s chart using flat fan even spray nozzles for band spraying
illustrates the effect of nozzle selection. Different nozzles increase the flow rate but, because of the
constant spray angle, the spray width remains the same while the spray volume is increased:
Litres / hectare @ km/h
2
3
4
5
1
0.23
80
0.84
81
54
41
33
2
0.32
80
0.84
115
77
58
46
3
0.39
80
0.84
141
94
71
56
1
0.34
95
1.09
94
63
47
38
2
0.48
95
1.09
133
89
66
53
3
0.59
95
1.09
163
109
81
65
1
0.46
105
1.30
105
70
52
42
2
0.64
105
1.30
148
99
74
59
3
0.79
105
1.30
182
121
91
73
1
0.68
105
1.30
157
105
79
63
2
0.97
105
1.30
223
148
111
89
3
1.18
105
1.30
273
182
136
109
1
0.91
105
1.30
210
140
105
84
2
1.29
105
1.30
297
198
148
119
3
1.58
105
1.30
364
242
182
145
NOZZLE CHOICE Flat fan: Even spray (for herbicide at 1 m/s)
Pres.
Flown
Height
Width
Yellow
3
0.8
50
80
167
Blue
3
1.2
50
80
250
Red
3
1.6
50
80
333
Colour
• selecting the orange nozzle – with a flow rate of 0.23 l/min and a spray angle of 80°, the spray
width will be 0.84 m and spray volume will be 81 l/ha
• selecting the green nozzle – with a flow rate of 0.34 l/min and a spray angle of 95°, the spray
width will increase to 1.09 m and spray volume increases to 94 l/ha
• selecting the blue nozzle – with a flow rate of 0.68 l/min and a spray angle of 105°,
the spray width will increase to 1.30 m and spray volume increases to 157 l/ha
• selecting the red nozzle – with a flow rate of 0.91 l/min and the same spray angle of 105°, the
spray width will remain at 1.30 m but the spray volume increases to 210 l/ha.
Bar
l/min
cm
cm
Rate
l/ha
• selecting the yellow nozzle – with a flow rate of 0.8 l/min at 3 bar, the spray width
will be 0.8 m and at 3.6 km/h (1 m/s) walking speed, the spray volume will be 167 l/ha
• selecting the blue nozzle – with a flow rate of 1.2 l/min, the spray width will remain
at 0.8 m but the spray volume increases to 250 l/ha
• selecting the red nozzle – with a flow rate of 1.6 l/min, the spray width will remain
at 0.8 m but the spray volume increases to 333 l/ha.
40 | Backpack sprayers
Backpack sprayers
2.8. Sprayer Maintenance
2.9. Problem Solving
Modern Backpack sprayers are designed so
that they can easily be cleaned, maintained and
serviced. Only a very few tools are required.
Occasionally sprayers will malfunction and require repair, regardless of how well they
are maintained.
Adhering to the following simple guidelines will help keep sprayers in good working condition while
reducing health risks and risks to the environment:
• Read the manufacturer’s service manual to check for guidance and any specific service
requirements for your sprayer.
• After finishing spraying, thoroughly clean the sprayer with clean water – the inside, the outside
and the parts of the sprayer, including lances and nozzles.
• Check for leaks and wear and tear – particularly the nozzles and tips, screens
and the correct seating of the O-rings.
• Check hose for wear
• Check hose clips and replace broken clips
• Check on / off switch for smooth operation
• Check and replace all damaged seals
• Lubricate piston seal with light oil
• Replace damaged nozzle
• Replace damaged valves
• Wash sprayer after use
• Replace any damaged parts when necessary.
• After servicing and re-assembling, return the clean sprayer to its storage out of direct sunlight,
protected from frost and where it will be secure from humans, animals and feed.
• Grease all moving parts if storing the sprayer for a long time or at the end of the season.
Local branches of crop protection companies and other organisations
can provide training and guidance on maintaining and using Backpack
sprayers.
Most issues with leaking or sprayers not in good working order can be
detected and resolved without third-party assistance.
The most common problem areas on a Backpack sprayer are shown below:
Blocked or dripping nozzle
Blocked filter
in filling cap
Difficult to operate
pumping lever
Leaking or blocked
spray release trigger
Read service manual Clean the sprayer
| 41
Check sprayer and trigger for leaks, wear and tear
Sprayer in storage
Leaking connection hose
Damaged spray lance
Problems with air chamber,
air cylinder or dip tube in
spray tank
42 |
Backpack sprayers
Backpack sprayers | 43
The most common problems are with leakages and blockages and the solutions to these problems are
shown below. Before starting to work and fix the problem, make sure that the sprayer is depressurized.
Problem
Causes
Solutions
1. Dripping, leaking
from spindle in the trigger
Unit not sealed properly
Reseal all caps on trigger
Worn O-ring
Replace the O-ring
Blocked trigger filter
Clean the filter
from nozzle tip
Worn rubber O-ring in trigger
Replace O-ring
Nozzle worn
Replace nozzle tip
from any joint
Unit not sealed properly, or worn rubber
Check seals and washers and replace if necessary
from the piston or diaphragm
Faulty piston or diaphragm seal
Lubricate seal or replace parts if faulty
from the lance
Damaged or bent lance
Replace the lance and tighten all joints
No pressure
Use lever to build up pressure
Solid particles in orifice
Using gloves, soak in clean, warm water or clear
using a thin stick, not wire
2. Blocked nozzle
Insufficient / no spray from nozzle
Check blockage is cleared by spraying clean water
Air cylinder orifice blocked or damaged
Clean the air cylinder and pump cylinder valves
Clogged filter in spray handle
Clean the filter
Jammed ball and washer in suction valve
Clean or replace ball and washer
Suction valve
Suction valve clogged
Clean suction filter; replace ball and washer if necessary
Air cylinder / air chamber
Loose seal between the units
Tighten seal; replace air chamber if necessary
Piston rod
Piston rod difficult to operate – lack of lubrication
Lubricate pump cylinder and reseat the piston rod
Faulty pressure valve
Valve seating incorrect, not functioning
ordamaged
Check seating and that valve is not sticking or damaged.
Replace if necessary
3. Cannot build up pressure
Discs and O-rings
Not seated properly
Reset disc or O-ring correctly. Replace if worn
Dip tube
Damaged, leaking or not fitted correctly
Check for damage, fitting and then tighten the check nut
Tank lid
Air hole blocked
Clean the air hole and fit the lid tightly
Worn nozzle
Check flow rate: if differs by more than 10 % from manufactures
given rate at a precise pressure, then the nozzle should be replaced
4. Wrong flow rate
When checking blocked nozzles wear protective gloves and never try to remove the blockage by
blowing into the nozzle. Clear the blockage using a small brush or a thin stick such as a toothpick
but do not use wire.
There are many types of Backpack sprayers. Their parts and accessories are explained and
advice is given on buying, maintaining and using a Backpack sprayer and solving problems
when something goes wrong. Knowing the types of nozzles available and selecting suitable
nozzles is important. 44 | Backpack sprayers
Backpack sprayers | 45
3. PERSONAL PROTECTIVE
EQUIPMENT (PPE)
3.1 Choosing appropriate PPE
Bayer provides general guidance on selecting and using PPE through its stewardship training
campaigns in many languages worldwide.
Bayer CropScience “Protect your skin” safety campaigns
Always wear appropriate Personal Protective Equipment (PPE) when handling and using crop
protection products and when cleaning up after spraying.
•N
ote that different products and application methods sometimes require the use of different
types of PPE.
•F
ollow the product label instructions for the PPE requirements when measuring, mixing,
spraying and cleaning. A dust mask is required when mixing powder formulations.
•T
he minimum requirement is the use of a cap or hat, long sleeved shirt, long trousers
and non-absorbent footwear.
• Wash gloves before removal to avoid secondary contamination.
• Avoid exposing spray operators and field workers to spray drift.
• Do not spray in windy conditions and during the heat of the day.
Personal Protective Equipment (PPE)
Bayer also provides comprehensive information to growers and spray operators on selecting
appropriate PPE for any Bayer product being used. A web-based application is already available in
several countries and the application is constantly being expanded. Check on the Bayer website to
see if it is available in your country. A login code is needed to start the application, called DressCode.
It can be found at www.dresscode.bayer.com.
46 | Backpack sprayers
Backpack sprayers
The following example shows the appropriate PPE for mixing / loading, for application (spraying)
and cleaning (used equipment) whe using one of Bayer’s fungicides on cereals in a European
country. In this case the same PPE are required for both mixing / loading and cleaning.
| 47
3.2 Personal Hygiene
It is advisable to bear a few points in mind concerning personal hygiene to protect yourself
when using and spraying crop protection products with your Backpack sprayer.
DRESSCODE – PPE for mixing / loading, application and cleaning
Broad rimmed hat
(e. g. Stetson)
Long sleeved
shirts and trousers
Protective Coverall
Long sleeved
shirts and trousers
Gloves
Gloves
Gloves
• All mixers, loaders and spray operators should wear suitable protective
clothing and waterproof gloves before starting work.
• Wash any chemical spills from skin and eyes with clean water immediately.
• Ensure an adequate supply of drinking water is available to avoid dehydration,
wash before drinking.
• Do not eat, drink or smoke whilst handling, working or spraying.
• Wash hands and exposed skin before eating, drinking or smoking.
• Wash protective clothing separately from regular laundry.
• Do not start work with chemicals if you feel unwell and stop work immediately
if you feel unwell during spraying
DRESSCODE – PPE for mixing / loading, application and cleaning
Boots / sturdy
footwear
!
Mixing / loading
Boots / sturdy
footwear
Application
Boots / sturdy
footwear
Cleaning
Bayer makes the following disclaimer with regards to
PPE recommendations:
The recommendations on PPE in this system are only made
for Bayer CropScience products. They are further only
made for the country in which the product is registered.
In case of two or more Bayer CropScience products being
used in mixture, the user has to use the highest protection
given for each product. Mixing with third party products is
not covered. Accidents are NOT taken into account when
recommending appropriate PPE.
Always read the label to find out whether additional requirements are
made, which are not covered by this information tool.
Always wear and use appropriate protective equipment and practice good personal hygiene
when using crop protection products, during spraying and when cleaning used equipment.
Bayer CropScience offers advice on selecting and using PPE for Backpack sprayer operators.
48 | Backpack sprayers
Backpack sprayers | 49
4. CALIBRATION AND
APPLICATION
Calibrating sprayers is essential to ensure that
products are applied accurately, safely and at
the correct dose rate to target crops. Calibration is easier with larger Backpack sprayers
because they have a more consistent flow rate.
Also, if the sprayer is fitted with a pressure
gauge, it provides a more constant pressure
and droplet size which will give a better and
more uniform spray pattern.
Sprayers should be checked and accurately
calibrated at least once each season, preferably at the start of the spray season. To get the
best service from sprayers, calibration should
include the full range of accessories and nozzles available for the best-possble accuracy.
Never calibrate a sprayer using chemicals – use clean water only!
Knowledge of the required spray quality and
droplet size is necessary when calibrating.
4.1 Spray quality
Nozzles produce different size
spray droplets according to
the pressure under which they are
used and these sizes are classified
into eight categories according to
an international spray classification
system (ASABE S-572.1). Each category is defined as a spray quality.
The qualities range from Extra Fine
to Ultra Coarse. The system allows
the spray operator to consider the
droplet size selection so as to balance good leaf coverage with the
risk of spray drift.
Bayer CropScience “Protect your skin” safety campaigns
Spray quality
Category
Symbol
Colour
code
Size range
(microns)
Extra fine
XF
Purple
Very fine
VF
Red
Fine
F
Orange
136 – 175
High
Medium
M
Yellow
176 – 220
Moderate
Coarse
C
Blue
221 – 350
Low
Very coarse
VC
Green
351 – 425
Very Low
Extra coarse
XC
White
426 – 620
Very Low
Ultra coarse
UC
Black
>620
Very Low
Most Backpack sprayers are calibrated to apply
only the fine, medium or coarse spray qualities.
These categories are often given on product
labels so that a product may have to be applied
as a Medium (M) spray quality which would be
~50
Spray drift
potential
Very High
50 – 135
Very High
colour coded yellow and have droplets in the
size range of 176 – 220 microns. The table below
also shows the spray quality categories and
shows how the risk of spray drift increases as
the droplet size decreases – more spray drift
with smaller droplets.
Normally, Extra fine, Very Fine and Very Coarse
to Ultra Coarse spray qualities are not used in
outdoor agricultural spraying. Extra Fine and
Very Fine droplets are highly likely to cause
spray drift and Very Coarse to Ultra Coarse
droplets are only needed for liquid fertilizer
applications. Medium is the most commonly
used quality for crop protection sprays providing the ideal mix of droplets large enough to be
effective and give good retention on the crop
but not too small to drift. If a product label does
not show a spray quality then Medium can
always be used.
Coarse quality is usually only used for soil
acting herbicides where spray drift must
be avoided.
The choice of droplet size and spray quality
will have an effect on the overall result and influence the relative crop coverage, the amount
of retention of the product on the crop, how
well the spray will penetrate the crop canopy
and the risk of spray drift as shown in the
following table.
Bayer CropScience “Protect your skin” safety campaigns
Spray quality
Relative
coverage
Spray retention
Canopy
penetration
Risk of
spray drift
Fine
Very Good
Very Good
Poor
High
Medium
Good
Very Good
Good
Moderate
Coarse
Moderate
Very Good
Very Good
Low
See section 5.3 Product labels for more details.
50 | Backpack sprayers
Backpack sprayers
Nozzle tip output
4.2 Sprayer calibration
Sprayer calibration is a process of selecting,
measuring and calculating. For example:
• Selecting
nozzles, spray height and pressure
• Measuring
walking speed, swath (spray) width
and nozzle output
• Calculating
flow rates and volume application rates
Measuring nozzle output (l/min)
Because there is a wide range of types and sizes
of nozzles available and different size spray tips,
it is important to choose the correct tip for each
individual spray job. Use nozzle manufacturer
guides to help in this process. Also refer to the
information in Section 2.7 above.
In general for most broadcast crop spraying,
nozzles that can provide an output of 50 – 200 l/ha
will be required.
There are four variables that are important
in the calibration process that all need to be
checked because changing any one variable will
have an effect on the product application rate:
To measure the output, spray water into a
measuring jug for one minute and repeat this
several times to measure the output of the
nozzle in l/min.
• Spray pressure
• Nozzle tip output
• Walking speed
• Swath width
Walking speed
Measuring walking speed
Walking speed should be at a pace that can be
maintained taking into account the field conditions and crop density in which you are walking.
Sprayer fitted with a pressure gauge
Spray pressure
Preferred types of sprayers include those with
a constant flow valve, those with a pressurevalve which allows users to pre-set pressure
or those with a pressure gauge on the lance
to enable monitoring and maintaining pressure.
Pressure must be suitable for the type of
nozzle selected.
Pressure must be consistent and maintained
throughout spraying. Any change in pressure
will affect the output from the nozzle.
Use the same walking speed for spraying when
calibrating the sprayer. Measure walking speed
over 50 m on the same type of ground as the
spray job. Use a stopwatch or wrist watch to
time the walking speed.
50 m
Time to walk / spray = 45 seconds
| 51
52 | Backpack sprayers
Backpack sprayers | 53
Practice walking at a constant speed, wearing PPE and with the Backpack spraying water.
Repeat the measurement a few times and calculate an average walking speed. Based on
the time taken, the calculation of walking speed is:
Using water to measure the effective
swath width, in this case 60 cm
Swath width
Swath width is controlled by the height that the nozzle tip,
or boom if being used, is held above the canopy of the crop
being sprayed. This applies when using deflector nozzles
where constant height should be maintained. When using
flat fan or hollow cone nozzles, the wand is waved back and
forth, creating an overlapping spray pattern. Constant height
is no longer important.
180 (factor) / time taken to spray 50 m = walking speed
For constant height spraying, the lance is held so that the
nozzle is as close to the target crop as practical to avoid
spray drift and to prevent operator contact. Any change or
variation in spray height will change the swath width and
thus the application rate.
To calculate the swath width, spray a length of dry ground
with water, using the pressure and nozzle height that will be
used for spraying. Measure the effective swath width before
the water starts to dry.
If the nozzle is not held at the same height when spraying then the swath width and the application
rate will change. If the crop should be sprayed with a nozzle height of 50 cm to give an application
rate of 200 l/ha, then:
The chart below shows actual walking speeds with the example above highlighted in red.
Measuring time to walk 50 m to calculate walking speed
Distance – 50. walking speed in km/h
Time to walk* (seconds)
83
71
62
45
36
29
Walking speed (km/h)
2.0
Walking süeed (m/s)
0.6
25
23
2.5
3.0
4.0
5.0
6.0
7.0
8.0
0.7
0.8
1.1
1.4
1.7
2.0
2.2
• Increasing the nozzle height to 60 cm (+20 %) increases the swath width to 0.7 m
and reduces the volume to 160 l/ha
• Reducing the nozzle height to 40 cm (-20 %) reduces the swath width to 0.5 m
and increases the volume to 240 l/ha
*walking – wearing PPE, with Backpack sprying water
Measuring time to walk 50 m to calculate walking speed
160 l / ha
200 l / ha
240 l / ha
54 | Backpack sprayers
Backpack sprayers | 55
Calculating the application (water volume) rate
In the case of using 10 m² for the area sprayed in the calibration, then the water volume used (ml)
will be the water volume / ha (l/ha)
To calculate the correct amount of product to add to the spray tank, first calculate the application
rate that you will be applying, if it is not already known.
Water volume calculation
Amount of water ues to spray 10 m²
To do this, measure out an area of 10 m² if using a 1 m swath width.
Preparing a 10 m² area based on swath width
Water volume used (ml)
50
100
150
200
250
300
400
Water volume / ha (l/ha)
50
100
150
200
250
300
400
Walking distance to spray 10 m²
If the swath width is:
0.5 m
0.75 m
1.0 m
1.25 m
1.5 m
1.75 m
2.0 m
Mark out the following distance (m)
20 m
13.3 m
10 m
8m
6.7 m
5.7 m
5.0 m
If the swath width you will use is 0.5 m then you will need to measure a distance of 20 m but if the
swath width is 1.25 m then the distance will be only 8 m.
Partly fill the sprayer with clean water up to one of the volume measuring lines, say up to the 10 litre
line. Spray the water over the marked distance with the sprayer set up for pressure and at the nozzle
height and walking speed to be used for spraying. At the end, refill the sprayer to the same line
with water from a measuring jug and read the water volume that was used.
The calibrated application rate in l/ha can be calculated from the equation:
Application rate (l/ha) = water volume used (ml) x 10,000 / area sprayed / 1000
If the calculation shows that the application
rate will be more than 400 l/ha, then this is too
high and not suitable for a Backpack sprayer.
To reduce the application rate, use a smaller
size nozzle or adjust spray technique until a
lower, manageable application rate is obtained.
If available, a calculator disc (dosage wheel)
can be used, using the sprayer output, tank
size and product rate / ha to calculate the
product rate for the tank. In this example, the
dose of 1.0 l/ha on Scale B is lined up with the
calibrated nozzle output of 150 l/ha on Scale A
(middle picture) and then using the tank size of
sprayer from Scale C it shows that for a 15 litre
sprayer, 100 ml product is required in the tank
(right picture).
Water volume calculation
56 | Backpack sprayers
Backpack sprayers
| 57
To calibrate a mistblower, simply fill the spray tank with clean water up to a defined line. Then
spray the water over a measured 100 m distance and calculate the amount of water sprayed by
refilling the tank to the same line with a measured amount of water.
If 1.12 litres water was sprayed, then:
Application rate = volume of water = 1.12 l x 100 = 112 l/ha
In this case the tank should contain 200 ml product + 19.8 litre water = 20 l of spray mixture in the
tank. The number of tank loads required to spray each hectare and the area covered by each tank
load can be calculated using the formula:
(FT) Full tanks / ha = (AR) Application rate (l/ha) / (TC) tank capacity
4.3 Product amount calibration
Once the application rate has been determined, it is then possible to calculate the amount of product required in the tank. During calibration it is important to maintain pressure in the tank so that
the nozzle will spray as soon as the trigger is pulled. Pump the lever 10 to 15 times when starting
and then once every 5 seconds during calibrating.
If a calculator disc is not available then the following method is recommended to be used to calculate the product amount required in the spray tank for broadcast spraying over crops.
From the calculation above, we have the example of the sprayer set up to spray at an application
rate of 150 l/ha. If the product lable shows that the required product dose rate is 1.5 l/ha for the
crop being sprayed, then the following equation can be used:
Product amount (ml/tank)
= Product dose rate (l/ha) x Tank capacity (l) x1000 (factor) / Application rate (l/ha)
58 | Backpack sprayers
Backpack sprayers | 59
Area covered by each full tank:
Area covered (m²) = 10,000 / Number of full tanks
Band applications
These applications are sometimes used along, over or between crop rows and can be for fungicides,
insecticides or herbicides in crops such as corn, soybeans and potatoes. For band applications, as
only part of the total area is treated, a lower amount of product is required which reduces chemical
and application costs. For example, if cotton is grown with a 80 cm row spacing, and the spray band
of an insecticide is 60 cm between the rows, then only 60/80 = 0.75 or 75 % of the area is sprayed. In
another example, if potatoes are planted with a spacing of 90 cm between the rows and a herbicide
band spray of 30 cm is used, then only 30/90 = 0.33 or 33 % of the area is sprayed, which reduces
the herbicide cost by 67 % compared with a broadcast spray.
Water volume calculation
The following chart shows the coverage, using the example above at 150 l/ha and 16 litre sprayer
giving 1067 m² coverage and 9.4 tank loads / ha:
Water volume calculation
Requi­
red
Cover­
age
l/ha
50
75
100
125
150
175
200
225
250
275
300
325
350
375
400
l/100 m²
0.50
0.75
1
1.25
1.5
1.75
2
2.25
2.5
2.75
3
3.25
3.5
3.75
4
m²) with tank capacity
14 l
2800
1857
1400
1120
933
800
700
622
560
509
467
431
400
373
350
15 l
3000
2000
1500
1200
1000
857
750
667
600
545
500
462
429
400
375
16 l
3200
2133
1600
1280
1067
914
800
711
640
582
533
492
457
427
400
18 l
3200
2400
1800
1440
1200
1029
900
800
640
582
600
554
514
480
450
20 l
4000
2667
2000
1600
1333
1143
1000
889
800
727
667
615
571
533
500
Three calculations are needed for band applications once the output of the sprayer is known.
Requi­
red
Cover­
age
l/ha
50
75
100
125
150
175
200
225
250
275
300
325
350
375
400
l/100 m²
0.50
0.75
1
1.25
1.5
1.75
2
2.25
2.5
2.75
3
3.25
3.5
3.75
4
quired für tank size / ha
14 l
3.6
5.4
7.1
8.9
10.7
12.3
14.3
16.1
17.9
19.6
21.4
23.2
25.0
26.8
28.6
15 l
3.3
5.0
6.7
8.3
10.0
11.7
13.3
15
16.7
18.3
20.0
21.7
23.3
25.0
20.7
16 l
3.1
4.7
6.3
7.8
9.4
10.9
12.5
14.1
15.6
17.2
18.8
20.3
21.9
23.4
25.0
In addition, there are separate calibration tests required for band applications and for
spot applications.
18 l
2.8
4.2
5.6
6.9
8.3
9.7
11.1
12.5
13.9
15.3
16.7
18.1
19.4
20.8
22.2
20 l
2.5
3.8
5.0
6.2
7.5
8.8
10.0
11.3
12.3
13.8
15.0
16.3
17.5
18.8
20.0
Application rate for the band
Application rate = 100 x Dose rate / ha / Row width (m):
60 | Backpack sprayers
Backpack sprayers
| 61
Product amount needed for the band
Spot applications
Dose rate for the band (l/ha) = Dose rate (l/ha) x Band width (cm) / row width
When making spot applications to single plants or small areas such as transplants, trees or horticultural pot plants, another calculation has to be made for the dose rate and application. In this
case, a dose rate in litres or kg/ha is not useful and the recommendation for the product will be a
concentration, for example, 75 ml/100 litres, which is 0.75 % product in water.
Amount of product for the tank / single plant application (I, kg) = Tank capacity (litres) x Product
concentration (% product) / 100
Product amount needed for the tank
Amount of product / tank for band (l) = Dose rate for the band (l/ha) x Tank capacity (l) / Application
rate for the band (l/ha)
The following table can be used to read off the
amount of product required when the product
concentration is known. It takes into account all
the main size tank sizes for Backpack sprayers.
The example above for a 20 l tank is shown by
the black dotted lines.
Field size calculation + irregular shapes
The following method can be used to calculate
the approximate area of irregular shaped fields
which are to be sprayed.
62 | Backpack sprayers
Calculating the approximate area of irregular
shaped fields to be sprayed
Backpack sprayers | 63
The area to be sprayed is inside the yellow
dotted line block. Firstly, divide the area into
square, rectangle, triangle or circular shapes.
Then calculate the area of each shape using the
formulae below. The total area to be sprayed is
the sum of the area of all the shapes.
64 | Backpack sprayers
Backpack sprayers | 65
4.4. Spray Mixture Preparation
Most crop protection products are liquid concentrates that will need to be measured and then
mixed with water prior to adding to the spray tank. Wettable granule products can be added
directly to the spray tank after weighing the correct amount. Ultra-low volume (ULV)
concentrates are added undiluted to a sprayer or mistblower that are specifically recommended
for the application of ULV products.
Follow these procedures when measuring and mixing products for application:
• Keep children and animals away from the
working area
• Clean water must be available for mixing the
spray and for washing
• Avoid all skin contamination by wearing protective clothing and waterproof gloves
• A dust mask should be worn when handling
dry, granule and powder products
• Measure products accurately to ensure that
the correct dose is used
• Measure out and mix products near to the field
where they are going to be applied
• To avoid accidents, the Backpack sprayer
should be placed firmly on an even surface
before filling with the spray solution
• Avoid any risk of product or spray mix contaminating water sources such as streams, wells
and ponds by mixing away from these sources
• All measuring equipment used should be for
pesticide use only, never for any other purpose
(e.g. measuring jug, mixing bucket and stirrer,
funnel) – never use hands for mixing or stirring
• Work carefully to avoid spillages. Clean up any
spillages with absorbent material and dispose
of appropriately
• Carefully clean all used equipment after use at
the end of spraying
• Wash hands and exposed skin with soap and
clean water before eating, drinking or smoking
Measuring time to walk 50 m to calculate walking speed
Follow the instructions on the product label and ensure you are using the correct dose rate or concentration (dilution rate) for the crop and application intended. Follow mixing instructions. Do not
use higher doses or concentrations than recommended because that will not make the product or
spray more effective and it may cause crop damage. It can also become expensive and in some
countries could be illegal. Lower doses, below the product’s recommended dose rate, will be less
effective, produce poor results and increase the risk of resistance.
If you are preparing a mixture of more than one product for the spray tank
• Check the labels of the products used for mixing instructions
• Ensure that the products are compatible and can be mixed
together (if necessary do a pre-mix test before)
• Check what PPE must be used for the products and use the
best protection to cover all products
• Check the labels for instructions on the order of mixing the
products. If there are no instructions given, then mix any solid
products first and then followed by liquid products
• Half fill the spray tank with clean water
• Add the first product and use a stick or stirrer to mix it with
the water
• Add then next product and continue to stir
• Add the rinsings from cleaning the empty containers
• Fill with the rest of the water and close the lid tightly
Now the tank mixture will be ready to spray.
66 | Backpack sprayers
Backpack sprayers
Spray technique
4.5 Application – Good Spraying Practice
Ensure the product is suitable
for the intended use
Before starting the preparation to spray, ensure that the
product being used is registered in the country and that it
has a label for the intended use.
| 67
Wind speed chart advising whether conditions
are suitable to spray
If you are using flat fan nozzles then the crop
will have to be sprayed by waving the spray
lance back and fore to get a homogenous and
overlapping spray pattern.
Read the label (or have someone read it and explain it to
you) to confirm that the product is suitable and safe for the
intended use.
You should understand the instructions including the
maximum number of applications that can be made and the
pre-harvest interval.
Walking speed
If the calculated walking speed is not maintained whilst spraying it will have a significant effect on
the application volume and the dose rate of the product being applied.
If the calculated walking speed is 0.8 m/s to deliver an application volume of 150 l/ha,
Wind speed and direction
Before starting to spray, check the local weather situation to determine whether the wind speed
and direction are suitable so that the application will be uniform and accurate and that spray drift
from the target area can be effectively avoided.
Always spray with and not against the wind.
The most important goal when applying a pesticide with a Backpack sprayer is to get a uniform
distribution of the spray droplets on target crop foliage in a safe and efficient manner. Checks
must be made frequently to ensure that the sprayer is operating correctly and that good coverage
of the crop is being obtained.
Wind speed chart advising whether conditions are suitable to spray
Wind speed
metre / sec
Beaufort
scale
Wind speed and indication
Spray?
0 – 0.2
0
Calm, no wind, smoke rises vertically
Yes
0.3 – 1.5
1
Light air, smoke drifts showing wind direction
Yes
1.6 – 3.4
2
Light breeze, leaves russle, wind leaves and twigs constantly
Yes
3.5 – 5.4
3
Gentle breeze, moderate wind, leaves and twigs constantly
5.5 – 7.9
4
Moderate breeze, small branches move, raises dust or
loose paper
8.0 – 10.7
5
Strong / very strong, small trees kept in motion
Yes
Avoid spraying >5 m/s. Use drift
reducing (deflector nozzles
No
• By walking too slowly at 0.5 m/s, the application volume will increase towards 200 l/ha
• By walking too fast at 1.1 m/s, the application volume will reduce towards 100 l/ha
At the same time, if the dose rate of the product being sprayed is 2.0 l/ha, then walking too fast
at 1.1 m/s will reduce the dose rate to 1.45 l/ha and walking too slowly at 0.5 m/s will increase the
dose rate to 3.2 l/ha.
Use a spray plan if spraying a large area to
ensure that all areas are treated only once
and accurately.
The effect on application volume by changing
walking speed during spraying to spray
Always start spraying on the upwind side of
the crop so that any spray drift moves downwind away from the operator into the crop.
When spraying:
• Maintain the calibrated walking speed as
accurately as possible which should be a
steady and maintainable pace
• Maintain the pressure as close as possible
to the calibrated pressure at all times
• Do not walk through crop areas that have just been sprayed
• If using deflector nozzles, keep the nozzle constantly at the correct height above the crop canopy
• Avoid spray drift particularly onto field workers, animals, flowering crops and water sources such
as canals, ponds and streams.
68 | Backpack sprayers
Backpack sprayers | 69
Spray coverage
Checking spray coverage by
spraying bare ground with water
To obtain uniform distribution of the spray when using a flat
fan nozzle, the crop should be sprayed by waving the lance
back and fore with an overlapping pattern over the crop.
Preventing operator and
environmental contamination
Make sure the sprayer is not leaking prior to use
to avoid any risk of personal contamination. A
leaking sprayer must be fixed before it is used
again.
A good way to monitor spray coverage of the crop is to
spray bare ground with water in the same way as the crop
would be sprayed and to visualize whether the spray coverage is uniform and effective.
Avoid making contact with or walking through
crops that have just been sprayed and that
have wet leaves.
Note the direction and strength of the wind and
never spray into the wind. Wind speeds of 2 – 10
Waving the lance back and fore over the crop
when using a flat fan nozzle
km/h (0.6 – 3 m/s) are the best conditions for for
Backpack spraying. Above this limit there will
be an increased risk of spray drift.
Note any restrictions on the product label
concerning protection of bees and other pollinators and avoid spraying if they are active on
the crop. The best Backpack sprayer practices
will do much to avoid any negative effects on
human and animal health and the environment.
Cleaning the sprayer
Keeping a log
Maintaining a spray log is good management practice. A manager or owner may even require a
spray log to analyse crop spraying results. Sprayers are legally required to keep records of all
activities in some regions and countries and the records often have to be kept for several years.
Log sheet for a crop protection application
Date:
Reference No.:
Applicator´s name:
Certification No.:
Field reference:
Location / site:
Crop / variety treated:
Crop condition / growth stage:
Start time:
Finish time:
Wind speed:
Wind direction:
Temperature range:
Relative humidity:
Weather conditions:
Field irrigated?
1.
2.
3.
Dose rate
(kg, l/ha)
Water volume
(l/ha)
1.
2.
3.
Any observation / comments on the spray application:
Total amount
applied (kg, l)
Size of treated
area (ha)
left-over spray into ditches, streams, wells or
any source of drinking water.
Do not leave unused spray mixture in the
tank as it may degrade and not be safe to use
the next day or may be used accidentally for
another purpose. Pay particular attention to decontaminating the sprayer if it has been used to
apply a herbicide, particularly if it may be used
the next day to spray a fungicide or insecticide.
Traces of the herbicide in the tank could seriously damage other crops.
Cleaning a Backpack sprayer and disposing of left-over spray
No. Hours worked:
Target pest / disease / weeds:
Products used
(Full brand name)
At the end of the day’s spraying, empty and
clean the spray tank. The best method is to
partly fill the tank with clean water, add some
detergent if possible, and repeat the cleaning three times. Clean the outside of the tank
with water and finally partly fill the sprayer with
clean water and spray to flush and clean the
tube, lance and nozzle. The rinsings should be
disposed of responsibly. They can be disposed
of over a wide area or along the edge of the
field that has been sprayed. Do not dispose of
Total area treated (ha)
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Backpack sprayers
5. USING PESTICIDES
Pesticide chemicals are potentially harmful substances if they are not managed in a responsible
way. They must be bought, transported, stored, handled, used and disposed of safely.
Buying
• Buy only from a reputable dealer that can provide information on the product and confirm that it
is suitable for the intended use
• Do not buy a product that has a damaged or leaking container
• Do not buy a product that is not intact in its original container
• Buy products in suitable pack sizes and amounts as required to keep storage to a minimum
• Check the label for batch number and manufacture or expiry date
• Read the label and be sure you understand the safety precautions of the product or ask for advice
| 71
Disposal
• Disposal covers both pesticide waste and empty containers
• After spraying, all empty containers (metal cans and drums and plastic bottles or jugs) must be
disposed of in a safe manner or stored until they can be disposed of safely
• Triple rinse (wash three times with clean water) empty containers and add the rinsate to the spray
tank as part of the spray solution being prepared. Do not rinse empty containers into rivers,
streams or ponds
Triple rinsing
1. Hold empty container for 10 seconds over the spray tank to empty any chemical into the tank
2. Quarter fill the container with clean water and replace the lid tightly
3. Shake the container for 30 seconds and then drain the rinsate into the spray tank for 30 seconds
4. Repeat the rinsing process another two times, emptying the rinsate into the spray tank.
Triple rising empty containers after spaying
Transporting
• Be sure to transport pesticides in accordance with any local legislation
• Pesticides and spraying equipment must be stowed safely in a vehicle and separately from the
driver and passengers, animals and all other goods especially food and feed
• Transport products from storage on the farm only in their original containers
• Be prepared to be able to safely contain any accidental product spillage using absorbent material
such as sand or soil
Storage
• Check the product label for any specific guidance on storage conditions
• Keep pesticides locked away and out of the reach of children
• Chemical stores should be dry, have a solid floor, be ventilated and protected from
excessive heat, frost and flooding
Handling
Handling products has already been dealt with separately in sections 3. Personal Protective
Equipment, 3.2 Personal Hygiene and 4.4. Spray Mixture Preparation.
Buying, transporting and storing pesticides
• Dispose of emptied, cleaned containers through local recycle schemes or other well managed
methods as defined by local legislation
• Do not bury, burn or recycle unwashed containers
• Washed containers can be buried, away from dwellings, wells, waterways and crops, after being
punctured and crushed
• Never discard empty containers or the rinsate in fields, ditches or in any waterways
• Never save or re-use empty containers for any other purpose
• Keep children and animals away from containers, rinsate and any waste.
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Backpack sprayers
5.1. Pesticide Legislation
5.3. Product Labels
Pesticide legislation exists in many different forms in most countries with strict regulations covering buying, transporting, storing, handling, using, equipment cleaning, waste disposal of products,
containers and spillage materials and keeping records of pesticide use.
In all countries where legislation exists, the rules must be followed. Where there is only limited or
no legislation, then the recommendations given above can be applied so that all aspects of handling pesticides and using spray equipment are as safe as possible.
The product label is a legal document providing precautions and restrictions for use of that particular product. The label is also the main source of information to understand what the product is, for
what purposes it can be used and how to use it safely and correctly as well as what to do in case of
an accident.
Always read and understand the product label – and follow the instructions.
5.2. Hazard Classification
The hazard classification of pesticides is
a universally adopted code referring to the
hazard of using a product based on its toxic
properties. There are five classes and their
descriptions are shown aside. The colours
are the same as those used on the pictogram
bands on product labels. The classification
is important for Backpack spraying because
the risk of exposure to the product is greater
when the operator has a Backpack on his back
rather than driving a tractor or pulling a ground
sprayer. It is best to avoid using class 1 (red
band) hazardous products for Backpack spraying especially if a less toxic product is suitable
and available for the intended use.
| 73
Hazard classification
1a. Extremely hazardous
1b. Highly hazardous
2. Moderately hazardous
3. Slightly hazardous
4. Unclassified
• The instructions must always be available in a locally understood language
• In some cases, the label is extended to detachable or separate leaflets to be able to cover all the necessary information
and additional information may be provided on an accompanying leaflet
• Read and understand the label or seek expert advice before
using any crop protection product
• Confirm that the product is suitable and approved for the intended purpose (the crop, the target pest, disease or weed,
the application rate) and that the expiry date has not been
reached
• Use suitable nozzle types, tank pressure and water volume
as indicated on the label
• Prepare the spray mixture and apply the product only for
a use that is stated on the label
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Backpack sprayers
A typical product label is basically separated into five sections:
1. The Product
A description of the formulation type and the amounts of all the active ingredients in the product
2. P
roduct description
The local registration number and safety and use instructions for operator and environmental
protection as well as the storage and disposal guidance
3. P
ictograms
They can be found as the bottom panel on a colour band with the internationally agreed symbols
used to describe in pictures rather than words the safety requirements for both preparation and
application of the product
4. M
anufacturer
The centre panel contains information on the name, address and emergency contact number of
the manufacturer and maybe the local supplier with the batch number and date of manufacture
or expiry date of the product
5. D
irections for use
With a list of crops, pests, weeds or diseases against which the product can be used according
to Good Agricultural Practice and with legal responsibilities. The dose rates will be given as a:
a. c
oncentration (g or ml product / litre water) and the user must decide how much
spray to use per hectare, or
b. a
s a dose rate / area (g, kg, ml or litre product / ha or acre) and the user must decide
the amount of water to use per hectare, adjusting to fit the conditions and growing area.
Backpack sprayers
| 75
Pictograms
Pictograms are an agreed set of pictures that are used on pesticide product labels to describe risk
reduction measures that should be followed when using pesticides. They have been accepted
worldwide since the mid-1980s.
There are four groups of pictograms covering Storage, Activities (handling and application),
Advice (on using PPE) and Warnings (concerning the effect in the environment).
The complete set of pictograms for pesticide product labels
This section also contains guidance on preparing and applying the product as well the restrictions
on pre-harvest intervals (PHI) and re-entry into treated fields. It will also contain advice on first aid
procedures and medical treatment in the event of accidents.
Basic layout of the sections on a typical pesticide product label
The pictograms on a product label are arranged on a colour band that describes the hazard
classification of the product (see section 5.2. Hazard classification) and the hazard is written
in the local language. Pictograms are always in five groups, from the left:
• Storage
• PPE required for mixing and preparing the spray
• PPE required for application
• Advice for washing
• Environmental hazards
76 |
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Backpack sprayers
Pictogram colour bands from product labels
| 77
To be well prepared to deal with any accident, have the emergency telephone numbers of the local
doctor, hospital or medical centre readily available and proceed as follows:
• If you see a spray operator in distress stop
him from spraying and provide assistance
• Move the spray operator from the source of
exposure to fresh air
• If you feel unwell, sick or dizzy, stop work and
seek immediate medical attention
• In case of skin contact, remove contaminated
clothing and wash skin with plenty of soap
and clean water
• In case of eye contact, rinse eyes with plenty
of clean water
• Keep the affected person calm and comfortable and obtain immediate medical attention
• Transport patient in a stable condition,
preferably laying on his side, to the doctor
or medical centre
• When possible show the doctor the
product label
• If the patient stops breathing perform
artificial respiration
• Do not give any liquid to the patient and do
not induce vomiting, this should only be done
by the doctor or medical centre
First aid in case of an accident
The colour bands are assigned to products as follows:
• GREEN – no acute hazard during normal use
• BLUE – caution
• YELLOW – harmful
• RED – very toxic / toxic
5.4. First Aid in Case of Accidents (Emergency Procedures)
When using crop protection products an accident could be:
• An accident during transportation where products are spilled on a road and / or
the driver or passengers are contaminated
• An incident on the farm when a spray operator is contaminated with product or spray
• Exposure of the spray operator to the spray mix during or after spraying
It is easier to prevent any of these accidents from occurring than to treat a patient following an
accident. Crop protection products should be handled carefully, following the label guidance and
by using personal protective equipment.
Be prepared to deal with an accident – you should know where the nearest doctor or
medical centre is located and have their telephone numbers. If you feel unwell during spraying,
stop work and seek medical attention.
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Backpack sprayers
6. SUMMARY
Invented over 100 years ago, the lever-operated Backpack sprayer has become the most common
type of sprayer for applying crop protection products in agriculture and horticulture worldwide.
They are particularly suitable and the most economical means of enabling farmers, growers and
operators to protect crops, particularly in small scale farming.
They are relatively easy to use once users become familiar with calibration, maintaining constant
pressure, pumping, walking speed and swath widths. With good maintenance, they can give years
of useful service.
Backpack sprayers
7. CONVERSION TABLE
To convert from
Into
Multiply by
AREA
acres
ha
sq feet
sq meters
ha
acres
sq meters
sq feet
0.4047
2.471
0.093
10.76
DENSITY
grams / litre
pounds / gallon
pounds / 100 gal
grams / litre
0.8345
119.83
LENGTH
feet
kilometres
meters
miles
meter
miles
feet
kilometers
0.305
0.6214
3.281
1.609
MASS
kilograms
kilograms / ha
ounces
pounds
pounds / acre
pounds
pounds / acre
grams
kilograms
kilogram / ha
2.205
0.8922
28.35
0.454
1.121
PRESSURE
atmosphere
bars
pounds / sq inch (psi)
pounds / sq in (psi)
pounds / sq in (psi)
bar
14.70
14.50
0.067
SPEED
US gallons / min
feet / sec
meters / sec
meters / sec
miles / hour
miles / hour
km / hour
km / hour
m / sec
litres / sec
kms / hr
kilometers / hr
miles / hr
km / hour
m / sec
miles / hour
m / sec
miles / hour
0.063
1.097
3.6
2.237
1.61
0.447
0.621
0.278
2.237
TEMPERATURE
temp (C°) + 17.78
temp (F°) - 32
temp (F°)
temp (C°)
1.8
0.56
VOLUME
Imp gallons
litres / ha
litres
litres
US gallons
US gallons / acre
litres
fl oz / acre
US gals
Imp gals
litres
litres / ha
3.78
13.68
0.264
0.22
3.785
9.354
| 79
80 | Backpack sprayers
Backpack sprayers
NOTES
| 81
BAYER CROPSCIENCE AND
SUSTAINABLE AGRICULTURE
300 years ago, Hans Carl von Carlowitz, a farsighted mining inspector in Germany, recognized the
importance of sustainable reforestation in ensuring a lasting supply of wood for the mining industry. These days, a scarcity of wood would hardly present an existential threat to most societies.
The challenge facing us now and in the future is global food security, with the world’s population
increasing by around 80 million a year and limited arable land available. In other words, the most
pressing global challenge is to intensify agricultural productivity in a sustainable way.
Bayer CropScience approaches this challenge holistically by connecting economic success in agriculture with environmental and social responsibility for all the partners involved. In practical terms,
Bayer promotes sustainable agriculture and strives for excellence in three ways:
• Providing innovative solutions (plant protection products, seeds, traits and services) to farmers
and other partners along the food value chain to protect and enhance crop yield and quality
• Proactive stewardship to ensure user protection, environmental preservation, plant health and
food safety
• Partnerships to enhance the quality of life in agricultural communities.
In this way, Bayer CropScience is playing its part in enhancing global food security.
Peter Ohs
Senior Global Product Stewardship Manager
Tel. +49 (0)21 73 – 38 42 98
[email protected]
Bayer CropScience AG
Alfred-Nobel-Str. 50
40789 Monheim
Germany
www.bayercropscience.com
© 2015 by Bayer CropScience
SBS-15 1008
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