4-Stroke Petrol Knapsack Sprayer

A 4-stroke petrol knapsack sprayer is a back-carried 20-25 litre HDPE tank coupled to a small petrol engine that drives a piston or plunger pump for plant-protection spraying. The configuration combines the autonomy of a manual knapsack with the discharge pressure of a power sprayer.

Function

The engine drives a positive-displacement pump that pressurises spray liquid from the on-board tank through a hand-held lance with selectable nozzles. The unit is intended for medium-canopy field crops, vegetables and orchards where neither a Knapsack Battery Sprayer (limited pressure) nor a Tractor Mounted Sprayer (poor manoeuvrability) is appropriate.

Design and specifications

Industry-standard prime movers are the Honda GX35 4-stroke (35.8 cc, 1.6 HP at 7000 rpm) and the 2-stroke 139F. The GX35 is widely adopted because it can be tilted through 360 degrees and exhibits low vibration. Tank capacity is typically 20-25 litres in HDPE, with adjustable padded shoulder straps.

Operation

The operator pressurises the lance through a trigger valve; flow and droplet size are tuned by changing nozzle tips. Engine speed governs working pressure. Compared with 2-stroke units, 4-stroke engines run on neat petrol (no oil-mix), emit less smoke and offer better fuel economy, but weigh slightly more.

Subsidy and adoption

Petrol-engine knapsack sprayers are tested at the Central Farm Machinery Training and Testing Institute (FMTTI) Budni and regional FMTTIs under ICAR-CIAE plant-protection equipment trials. A valid FMTTI report makes the model eligible for Sub-Mission on Agricultural Mechanization (SMAM) subsidy (40-50% to individual farmers) when purchased from a registered dealer (Agri Machinery Dealer Ecosystem).

References

Honda Engines - Agricultural Equipment. Honda Engines.
CFMTTI Budni - Machines. Central Farm Machinery Training and Testing Institute, Budni.