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Application
greater efficiency,
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v. 5/2/2009

Spray Nozzle Data
| Nozzle data | Sprayers | Methods | Definitions | Networking & tools | Rational Pesticide UseProjects |

This page illustrates the main nozzle types and some of the droplet size data that is available in the DROPDATA database. Data and pictures are available on:

 

Hydraulic Nozzles

See: The guide to hydraulic nozzles and examples of droplet size spectra of various nozzles.

Flat-fan nozzle

Standard flat fan nozzles are perhaps the most widely used nozzle in western agriculture. They commonly are fitted to both vehicle-mounted and manual hydraulic sprayers.

A flat fan nozzle: the 110 03

A cone nozzle fitted to the Chinese 'River Mountain' sprayer. Nozzles such as this are very common in Asia.

Current research on narrow-angle cone nozzles:

Hydraulic hollow cone nozzle

Optimising dose transfer to cocoa pods and other small biological targets

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Links: hydraulic nozzles:

Home Grown Cereal Authority nozzle calculator for grains and oilseed-rape.

Protocols for hydraulic nozzle evaluation: the BCPC Expert Working Group on Pesticide Application

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Air Shear Nozzles

Air shear nozzles are most commonly found on motorised mistblowers; these now have many uses, but one of the first was achieving good droplet coverage for control of mirids in the tall cocoa trees of West Africa. They also can be used for fungicides, which perhaps require the greatest efficiency of coverage of all the pesticide types. However, they are out the price-range of many smallholder farmers.

The most common design of nozzle is of the air-shear type, in which thin layers of liquid are introduced into the air stream and thus produce fine sprays.

Illustration: nozzle of a 'Stihl' SR420 mistblower with baffle plate

 

Rotary Nozzles

CDA droplet formation

Rotary (spinning disc and cage) atomisers usually produce a more uniform droplet size spectrum than conventional nozzles, and have proved to be the most successful way of delivering pesticides in the form of Controlled Droplet Application (CDA). CDA can be defined in terms of optimising technology to achieve a biological objective: delivering appropriately sized droplets (within practical engineering limits) for maximising the control of a given pest target, (where this is known).

Since CDA atomisers are capable of maximising coverage at very low volume application rates, they are frequently used for specialised, targeted application techniques such as seed and nursery treatments.

High speed photograph of ligament formation on the periphery of a rotary atomiser. (Photo courtesy Micron Sprayers Ltd.)

Droplet data on Motorised Mistblowers

Motorised mistblowers may be supplied (or retro-fitted) with rotary atomisers to improve the quality of droplet spectrain order to lower volume application rates. CDA techniques have necessitated detailed analysis of formulation, droplet size and recovery: especially with particulate agents such as biopesticides. This paper describes droplet size work that was carried out on spinning disc (handheld) and motorised mistblower nozzles, with oil-based and aqueous formulations. 

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Other atomisers: Foggers and Electrostatic Application

Paper (Matthews & Bateman, 2004, AAB): A rotary atomiser operated at 17,000 rpm with a flow rate of 35ml/min is proposed as a reference nozzle to differentiate between the spray spectra produced by mist and fog application equipment.
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Electrostatic spraying: Whatever happened to the 'Electodyn'? ... ED use in Forestry.

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Issues

Disappointingly few farmers world-wide are aware of the true performance of hydraulic nozzles, which inefficiently use large volumes of water, but remain by far the most important method of pesticide application. Worse still, recent emphasis in application research has focused on the reduction of spray drift (especially in Europe and N. America). The most common solution to be implemented to date has been to increase droplet size spectra (without necessarily improving spray quality); thus spray application has probably become generally more inefficient.

Spray drift:

The UK Government's Pesticide Safety Directorate gives guidance on many pesticide issues relevant to N. European agriculture. The UK has pioneered work on reducing spray drift: developing the first classification scheme for commonly-used flat-fan nozzles, then later developing the Local Environment Risk Assessment For Pesticides or LERAPS protocols.

In the USA, the spray drift task force was set-up to develop generic data base on premise that spray drift behaviour is independent of active ingredient. See: http://www.agdrift.com/.

Much of the focus was on aerial spraying - for which rotary nozzles are available and recommended for ULV to achieve high work rates.

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Note

These data are placed in the public domain on the understanding that:

  • The data on nozzle performance is for information and guidance only, and have no commercial or legal implications whatsoever.
  • All readings have been obtained using commercially available nozzles and blank formulations (unless stated otherwise); the work was carried out either as part of a publicly-funded project or in the authorís own time. None of this information has been obtained during contract research (unless permission has been given by the contractor).
  • This data is contributed to the public domain in the spirit of open access to useful scientific information. We have taken reasonable efforts to make accurate measurements (which have been replicated, unless stated otherwise), but mistakes may of course occur. Any comments, criticisms or other observations should initially be directed to the author, who will try to clarify statements or correct errors.

For more information contact us. As well as pursuing our current research programme, we are able to carry out contract R&D on:

  • Measurement of sprayer performance (especially droplet sizing) for commercial product development and registration.
  • Droplet sizing of new formulations and adjuvants (provided they are in WHO mammalian toxicity class III or above).
  • Assessment of durability of sprayers and nozzles under simulated operational use.
  • Consultancy on any of the subject matter in the DROPDATA pages.

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