Manual (Knapsack) Sprayers

Overview
• The types of available spraying equipment
Manual (Knapsack) Sprayers
• Important features of hydraulic spraying
equipment
• Specifications
• Special adaptations
• Conclusions and further information
RPB: Manual_sprayers: v. 2.2
Sprayers
(pumping mechanisms)
An old technology
NB In several
languages
“sprayer” =
“pump”
The “Galloway” knapsack pump
Manual (knapsack) sprayer options
compression
side lever
Pressurised knapsack sprayers
 Non-pressure retaining (manual pumping)
(often used by
smallholder farmers)
 ‘trombone’
 Pressure retaining
(now uncommon)
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Non - Pressure Retaining Sprayers
Designed for public health (mosquito control - IRS)
Non-pressure retaining (Hudson) type
• meter / pressure release valve
• pressure drops over time
• optional pressure control valve
It can happen!
Testing Compression Sprayers for WHO
Fatigue test: 12000 cycles
Testing …
International guidelines
Side-lever Sprayers:
Pumping mechanisms
Diaphragm type
(no piston - less wear)
Piston: internal or external
(achieves higher pressures)
Variations: side lever / over-arm
Pressure chamber configurations
Electrical / 2 stroke motor pump
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Side-lever knapsack sprayers
SLK: piston type
diaphragm pump
internal
External
Pressure
chamber
Over-arm type
Tank materials
Motorised hydraulic sprayers
Motorised pump (2 stroke engine)
polyethylene:
light, durable
Pumping mechanism:
electric
2-stroke engine
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High pressure sprays / jets
Stationary pump and extended hose
system (portable line)
Manual remote pumps
Hand operated pump
Stirrup foot pump
Motorised pump
Glass-house
(plumbed-in)
Often high volumes
… spray quality over swath?
Centralised Spraying Units (CSU)
enables better supervision of pesticide mixing
Others …
• Flit guns / spray cans
• Handymist:
twin-fluid
atomisation for
production of
small droplets
Manual remote pumps
• 2 person operation
• hand or foot operated
• moderately high (>1 mPa)
pressures possible
SLK - measured dose
Guarany (Brazil):wraparound sprays for trunks,
fruits etc.
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Accu-Dose
Key features: manual sprayer design
metered dose
of spray from
any hydraulic
nozzle
(the 5 bulls)
Portable (not heavy: must be <25 Kg when
full)
Comfortable (especially straps)
Durable (>3 seasons trouble-free use)
Affordable (< € 50)
Repairable (with simple tools)
(after E.W. Thornhill)
Major design features: safety
avoidance of leaks
how much residual
tank mixture?
Durability test
for LK sprayers
500 hours
trouble-free?
Only commercial adoption …
Closed systems?
(minimising exposure to
pesticide concentrates)
Membrane in PET bottle
pesticide dispenser
(experimental)
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photo: Jerry Cooper, NRI
Maximising under-leaf cover:
upwardly pointing nozzles
Booms and lances
Multiple nozzle
boom
Extended lance
Individual
nozzles fitted
to hydraulic,
side-lever
knapsack
sprayers.
Developed for
small-holder
farmers in E.
Africa.
(lightweight: glassfibre)
Knapsack and Tail-boom
Tail-boom height
adjustment screw
Tail-boom pivot at top
of mounting frame
Rates of Application
Tail-boom retained by
spring and side flanges
Hollow cone
nozzles (replaced
with blanking
plates for small
plants early in
the season)
• Dosage: rate of active ingredient
(a.i., active substance)
• Product rate
• Volume rate - with spray operation
Direction of travel
Summary
Standard calibration: what will you
measure?
Flow rate
Track spacing
Forward speed
Ubiquitous
Specifications - need for quality and
maintenance
Major types:
 Compression
• Especially non-pressure retaining (IRS for vector control)
 Side-lever knapsack
• Piston type
• Diaphragm type
 Motorised knapsack (electric or 2-stroke)
 Trombone, etc
Modifications to improve safety and enhance
dose efficiency of dose transfer (tail-booms,
directional sprays etc.)
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