Cooper Pegler CP3 Classic 20 Litre Knapsack Pesticide Sprayer

The Cooper Pegler CP3 Classic 20 litre knapsack sprayer is the bigger-tank sibling of the CP15: the same diaphragm pump, the same dual pressure settings, the same fibreglass-reinforced lance, with five more litres in the tank. For contractors and grounds teams covering large sites daily, that extra capacity means fewer trips back to the vehicle to refill.

Spindrift, the UK distributor, still services CP3 Classic sprayers that are over 50 years old. That comes down largely to the diaphragm pump: no moving parts exposed to friction, brass components throughout, and a build that has never been built down to a price.

The pump that sets it apart

Pressure comes from the controlled flex of a diaphragm rather than direct contact between moving parts, so there is almost no friction in the pump itself. That means it copes with the fine particles and sediment that wear out conventional piston pumps quickly, particularly in demanding field conditions. Brass components add further durability and chemical resistance, so the pump keeps delivering accurate, consistent performance long after cheaper alternatives have given up.

Why 20 litres makes a difference

Choosing between the CP15 and the CP3 Classic usually comes down to refill frequency. The CP3 carries a third more liquid than the CP15, which matters on a large grounds maintenance contract, a highway verge treatment or a commercial weed control programme: less time walking back to the vehicle, more time spraying. It is also the better choice with boom attachments, where liquid consumption is higher and the larger tank earns its keep quickly.

Key features

Dual pressure control valve

The integrated valve gives two fixed working pressures. The 1 bar setting suits low-pressure work such as fungicides and insecticides, where fine, even droplet distribution matters. The 3 bar setting delivers the higher pressure herbicide application needs, for a consistent flat-fan pattern across the target area. A switching tool is supplied as standard, so changing between settings in the field takes seconds. Accurate, repeatable application rates are a regulatory requirement under UK pesticide legislation, so this is not a minor detail.

Trigger assembly

Many operators rate the Cooper Pegler trigger assembly as one of the best available on a knapsack sprayer. It fits every lance tube and accessory across the Cooper Pegler range, which keeps things simple if you run more than one machine. The composite handle is shaped to reduce hand fatigue over long spraying sessions, and the lock-on feature lets you spray continuously without holding the trigger down. A filter built into the assembly gives extra protection against blockages right at the point closest to the nozzle.

Double filtration

Blockages cost time and disrupt spray quality. The CP3 Classic filters in two stages: a strainer in the filler neck catches debris as you fill, and a second filter in the trigger assembly catches anything that gets through before it reaches the nozzle.

20 litre tank

The transparent tank is rated at 20 litres, with an actual capacity of 25 litres. It is made from UV-stabilised polypropylene: light, chemically resistant and tough enough for daily outdoor use. Being translucent, it lets you check liquid levels without removing the lid. The wide 140mm filler neck makes refilling quick and reduces splashing, and a sealed lid with an integrated air vent stops leaks and prevents the vacuum that can otherwise make the pump falter as the tank empties.

Fibreglass-reinforced lance

The 500mm lance is made from glass-reinforced plastic, giving the rigidity of a metal lance without the weight or the risk of corrosion. GRP also resists the full range of chemicals in common professional use. Brass hose fittings connect the lance to a reinforced high-pressure hose, so the whole spray line is built to handle years of daily use.

Left or right-hand operation

The reinforced pumping lever adjusts for left or right-hand use without tools, so any operator can set the sprayer up in seconds. That matters on busy contracting sites where equipment gets shared between operators through the working day.

Shoulder harness

The rapid-fit harness uses polyethylene shoulder pads with polyester fibre braiding: practical and hardwearing for daily use. The quick-release fitting means the sprayer can be put on and taken off quickly when moving between treatment areas or in and out of vehicles.

Full specifications

What’s in the box

• Cooper Pegler CP3 Classic 20L knapsack sprayer
• Green anvil/reflex nozzle (AN1.2) for herbicide application
• Yellow hollow cone nozzle (HCX-02) for fungicide and insecticide application
• Pressure setting tool

Accessories and compatibility

The CP3 Classic works with the full Cooper Pegler accessories range. All lances, nozzles, booms and fittings are also compatible with the Series 2000 and Evolution families, so contractors running mixed fleets only need to carry one set of spares. Accessories worth knowing about for the CP3 include:

• Multi-nozzle spray booms (2, 3 and 4 nozzle configurations) for wider application widths
• Extended telescopic lance tubes for taller vegetation or deep shrub beds
• Spray shields for targeted spot treatment with reduced drift risk
• Flat fan, deflector and adjustable nozzle options for different applications
• Replacement diaphragms, seals and full service kits

Ideal applications

The CP3 Classic suits any job where a larger tank, or higher liquid consumption, makes 20 litres more practical than 15. It is particularly well suited to:

• Herbicide application on paths, car parks, highway verges and hard surfaces
• Weed control across large amenity planting schemes and landscape contracts
• Grounds maintenance on sports pitches, golf courses, parks and public open spaces
• Fungicide and insecticide treatment on ornamental planting, shrubs and hedgerows
• Local authority and highways weed control operations
• Estate, farm and forestry management
• Boom-assisted treatment of large grass areas and planting beds
• Garden use on large properties, or for keen gardeners with extensive grounds

A note on professional pesticide use

Anyone applying pesticides professionally or commercially in the UK must hold a PA1/PA6 certificate of competence, or an equivalent qualification. The CP3 Classic is designed and manufactured to European safety standards for professional spraying equipment. Regular calibration and maintenance in line with National Sprayer Testing Scheme (NSTS) guidelines will help keep application accurate and compliant throughout the sprayer’s working life.

More than 60 years in the field

Cooper Pegler has been manufacturing professional spraying equipment for over 100 years, and the CP3 Classic traces its lineage directly to the original knapsack developed with ICI Plant Protection in the 1960s. Like all Cooper Pegler products, it is made in the EXEL Industries factory in France to European standards, and spare parts are guaranteed to be available for at least ten years after any product is discontinued. If you need a 20 litre knapsack sprayer that stands up to professional daily use, takes the full range of accessories and stays serviceable a decade from now, the CP3 Classic is a solid choice.

Not sure the CP3 is right for you? If a 15 litre tank suits your workload better, take a look at the Cooper Pegler CP15 Classic. If you are considering the Berthoud range instead, the Berthoud Cosmos 18 Pro delivers 6 bar pressure and a built-in agitator mixer at a competitive price, while the Berthoud Vermorel 1800 is our most ergonomic knapsack for operators on their backs all day.

Need advice on nozzle selection, boom options, or whether the CP3 or CP15 is right for your operation? Contact the Phoenix Amenity Supplies team. We specialise in professional amenity spraying equipment and are happy to help.