British Crop Production Council

Expert Working Group on Pesticide Application

The Expert working Group

Members and meetings


The BCPC Expert Working Group for Pesticide Application (EWG-A) meets regularly to consider matters concerning the practical use and application of pesticides in crop protection and propose actions to improve application systems. The EWG-A assists the exchange of information on pesticide application between the chemical and equipment industry, users, trainers, advisors, researchers and others in order to promote developments of benefit to the crop production industry, its workers and the environment.

Nozzle Classification Scheme

Classification of sprays and nozzles serves two main functions:

  1. to define the spray quality most appropriate to the product, pest and target that can be communicated on the product label,
  2. to enable the use of sprays likely to be environmentally unacceptable to be avoided.

The first scheme for classifying sprays and nozzles was introduced by the (then) British Crop Protection Council (BCPC) in 1986: following-on from a paper presented by Doble et al. in 1985.  The original BCPC classification system relied on an analysis of the droplet size spectrum or 'Spray Quality'. Three broad categories covered most of the nozzles commonly found. The terminology used to describe them - Very Fine, Fine, Medium, Coarse and Very Coarse - was deliberately practical to appeal to the end-user. It has been managed by the BCPC EWG for Applications since then, in the hope that a new internationally agreed scheme would be introduced. 

In developing an improved approach to spray classification, Southcombe et al. (1997) maintained a practical approach based on a scientific background. They recognised that to evaluate all the causal parameters relating to droplet production, droplet life, transport, impact and off target drift was beyond the resources available at the time. They therefore concentrated efforts on developing a means to define the effects of these parameters in terms of a spray quality as previously, and with an additional element relating to the potential within a spray for some of its components to be displaced in a wind, which they termed the "Drift Potential" factor. This allows a difference to be made between sprays with the same nominal descriptor such as volume median diameter or spray quality category, but of very different widths in their droplet size spectra. They also recognised that a practical approach with relevance and appeal to the end-user is needed, and that the following criteria need to be met in a successful classification system :-

Protocols and Related Documents

There is always a need to re-confirm the protocols for the management, operation and technical aspects of the scheme to help those wishing to obtain classification of their nozzles. The files below give guidance and ancillary information on the procedures for collection and submission of data to BCPC for classification of nozzles into the categories of spray quality. 

Document Description


File size

Terms of reference of the EWG (original)

Terms of reference (2004)


Overview of project

57 KB

Protocol for the Malvern particle size analyser (600 mm lens)

8 KB

IPARC: procedures for spray analysis (2007 on)

12 KB

BCPC guide to fan nozzles

575 KB

Suggested extension of the BCPC classification scheme:
   distinguishing fogs and mists
50 KB

X572 spray nozzle classification adopted by the ASAE

78 KB

The following is a list of pdf files: concerning ISO standards (for 2008 and relevant to Group activities) available from the EWG-A.

  1. N744 SC6 WG4 Presentation Drift measurement
  2. N745 SC6 WG5 Presentation Knapsack motorised
  3. N747 SC6 WG8 Presentation In-situ test methods for air-assisted sprayers
  4. N746 SC6 WG6 Presentation Cleaning of Sprayers
  5. N748 SC6 WG11 Presentation Induction hoppers
  6. N749 SC6 WG12 Presentation Crop deposit measurement
  7. N750 SC6 WG14 Presentation Products simulate pesticides
  8. N751 SC6 WG15 Presentation Spray parameter recording
  9. N752 Presentation Agricultural Application techniques
  10. N741 NWIP Drift classification of spraying equipment: Potential spray drift measurement for field crop sprayers by the use of a test bench
  11. N742 NWIP Reciprocating positive displacement pumps - Test methods
  12. N757 CD 24253-2 Crop deposit measurement
  13. N756 CD 24253-1 Field deposit measurement
  14. N740 SC6 Report of the 25th meeting of ISO/TC23/SC6 Paris

Links to some other useful web sites:

AAB: The Association of Applied Biologists

ADAS - Environmentally sensitive farming
CropLife International
CPA: the UK Crop Protection Association
ECPA: the European Crop Protection Association
IAPPS: International Association for the Plant Protection Sciences
TOPPS: (Train the Operators to prevent Pollution from Point Sources) EU Initiative

VI: The UK Voluntary Initiative


1. Doble S J, Matthews G A, Rutherford I, Southcombe E S E (1985). A System for Classifying Hydraulic and Other Atomizers Into Categories of Spray Quality.  Proceedings British Crop Protection Conference - Weeds, 3, 1125-1133.

Note: This page (as with other information on the DROPDATA site) has been prepared in the spirit of free exchange of information, for research purposes only.  Whereas every care has been taken to ensure accuracy, we take no responsibility for the contents of these (often draft) files and would welcome any comments or additional protocols that readers may wish to contribute.

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