LERAP-Low Drift Star Ratings will be awarded to:

• complete boom spraying systems (‘sprayers’) designed for operation over arable field crops;
• nozzles or other spray generation systems (‘spray generators’) designed for use on boom sprayers.

Star ratings will be awarded by comparing the levels of drift from candidate sprayers or spray generators with corresponding drift levels from a reference system. This reference system shall be defined as an open structured boom construction fitted with F110/1.2/3.0 nozzles, manufactured from stainless steel, operating with a nozzle height above the target of 0.5 m. The reference sprayer will have the same nozzle specification along the whole length of the boom ie no special nozzle design will be used at the end of the boom. The reference sprayer shall be fitted with a boom suspension arrangement to provide isolation from both the rolling and yawing motions of the spray vehicle. Reference performance will be based on spraying of water and of a 0.1% solution of a non-ionic surfactant.

Star ratings will be awarded based on the criteria defined below.

Terminology and Drift Performance (measurable as ground deposit)

• No LERAP-Low drift rating
  Drift levels greater than75% of that from reference system.

• LERAP-Low Drift – one star *
  Drift levels greater than75% of that from reference system.

• LERAP-Low Drift – two star **
  Drift levels greater than 25% and up to 50% of that from reference system.
• LERAP-Low Drift – three star ***
  Drift levels up to 25% of that from reference system.
• LERAP-Low Drift – four star ****
  Drift levels up to 10% of that from reference system.

Applications for LERAP-Low Drift Star Ratings relating to either complete sprayers or spray generators will require the submission of a data package that must include:

1. a full technical description of the sprayer or spray generation system for which a LERAP-Low Drift Star Rating is to be claimed;
2. a definition of the operational settings and conditions (or ranges within an operational envelope) within which a LERAP-Low Drift Star Rating is to be claimed together with evidence of written instructions to operators as to how such settings shall be achieved;
3. evidence to show the level of drift reduction that can be achieved with the sprayer or spray generation systems in comparison with that of the reference system.

It is recognised that such evidence should comprise at least:

1. results from a series of field tests (for complete sprayers and spray generation systems) or wind tunnel measurements (for spray generators) specifically designed to provide data for a LERAP-Low Drift Star Rating as part of the LERAP scheme;
2. a collection of existing available information to support appropriate interpretation, extrapolation and interpolation such that the drift reduction requirements for a given LERAP-Low Drift Star Rating can be implied with a high level of confidence.

3.1 Drift reduction evidence from purposely conducted tests (‘targeted data’)

3.1.1 Complete boom spraying systems (sprayers)

Field tests must be conducted to an adequate defined protocol – see Annex 1 (PDF) or the draft International Standard for the field measurement of spray drift. Results from such tests must report a minimum of:

1. a profile of the measurable downwind drift deposits between 1 and 12 m from the end of the boom including measurements from samples collected at three separate distances between 2.0 and 6.0 m from the end of the boom using collectors positioned at the top of the target crop/grass/soil surface and designed to collect sedimenting spray drift;
2. details of the drift sampling methods used and particularly a description of the collecting surfaces and tracer techniques;
3. details of the conditions under which the measurements were made including a mean wind velocity measured at a height of 2.0 m above the ground, a mean air temperature at a height of 2.0 m above the ground and a physical description of the surface under the sprayer and over which the measurements of spray drift were made including the mean heights of vegetative cover;
4. data as in (i) and (ii) above for both the candidate sprayer and a system representative of the reference system;
5. evidence to validate the experimental approaches taken relating to:
   • the calibration of the machine prior to conducting the drift trial;
   • the calibration of any instrumentation used to monitor the sprayer and weather conditions during a drift trial;
   • the recovery and stability of the tracing system used.

Those submitting data packages to obtain LERAP-Low Drift Star Ratings are encouraged to submit as much relevant information as possible to enable an accurate definition of downwind drift profiles for both candidate and reference spraying systems. Data will be reviewed by comparing downwind drift deposition profiles for the candidate sprayer and the reference system with standardised reference drift profiles (see Figure 1.). Where the form of the downwind drift profile for the candidate sprayer differs from that of the reference system, a LERAP-Low Drift Star Rating will be awarded based on the highest level of drift in the 2.0 to 6.0 m region downwind of the end of the boom.

3.1.2 Nozzles or other spray generation systems (spray generators)

Protocols have been developed and published for sampling the airborne and sedimenting spray from both static and moving nozzles in wind tunnel conditions. Data can therefore be generated using such protocols with details of the measurement method being fully reported with the test results.

Results from such tests must report a minimum of:

1. the measured downwind airborne spray deposits collected at three separate distances between 2.0 and 6.0 m from the edge of the spray pattern from the spray generator(s), using collectors positioned 0.5 m below the spray release height designed to sample sedimenting spray drift; or the measured downwind airborne spray deposits collected at three separate heights between 0 and 0.5 m below the spray release height at a set distance of 2 m or greater from the downwind edge of the spray pattern from the spray generator(s), using collectors designed to sample airborne spray;
2. a description of the wind tunnel arrangement and sampling systems used including:
   • details of the spray generator mounting;
   • a description of the airflow conditions including the mean wind speed at spray generator height;
   • a description of the position and dimensions of the spray sampling system;
   • details of the tracing techniques used;
   • the floor conditions onto which the spray generator was spraying;
   • the sampling periods and methods of controlling spray generator output.
3. data as in (i) and (ii) above for both the candidate spray generator system and a nozzle representative of the reference;
4. evidence to validate the experimental procedures used including:
   • the calibration of control and monitoring equipment used to measure/control nozzle operating pressures, flow rates and wind tunnel air speeds;
   • the recovery and stability of the tracing system used.

Data will be reviewed by comparing downwind drift deposition profiles for the candidate and reference nozzles with standardised reference drift profiles. Where the form of the downwind drift profile for a candidate spray generator differs from that of the reference system, a LERAP-Low Drift Star Rating will be awarded based on the highest level of drift in the region 2.0 to 6.0 m downwind of the edge of the spray pattern.

3.2 Data packages based on results from existing field trials and wind tunnel experiments (‘interpolated data’)

It is recognised that for some sprayers and spray generators there may be a large body of drift performance data collected using protocols that differ from those referred to in 3.1 above which could be collated and interpolated to support a case for awarding a LERAP-Low Drift Star Rating. Such collation and interpolation must aim at generating a downwind spray drift deposition profile for the region 2.0 to 6.0 m downwind of a boom or nozzle spray pattern that can be compared with standardised profiles. Any such data package must demonstrate:

1. that the data used was collected in a way such that the likely accuracy and reliability can be validated;
2. that the methods of collation and interpolation are technically robust and reliable;
3. that results can be compared with those for the reference sprayer/nozzle condition.