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TWIN Research Articles

Here you can find a number of research results related to drift.   The TWIN sprayers are here compared with different other techniques as for example lowdrift nozzles.


The use of TWIN to Reduce Drift

Original Article:
The use of air assistance in a field crop sprayer to reduce drift and modify drop trajectories.
by: Taylor W, Andersen P.G. & Cooper S. 1989 Brighton Crop Protection Conference -weeds. 


  • More spraying hours available per day due to efficient control of droplets – even at high wind speeds.

  • Spray drift from a conventional sprayer and fine to medium droplets can be so great that operators are advised to stop when wind velocities are higher than 3-4 m/s. Twin sprayers control even fine and medium size droplets and reduces drift greatly. The volume drifting away from the target area at the higher wind velocities of 8 to 9 m/s, is less when spraying with a TWIN than that from a conventional sprayer working at it’s safe wind speed limit.

  • Under most conditions farmers get at least twice as many hours to perform an efficient spray job with the Twin compared to conventional spraying.

Extracts from the report:

twin-reduce-drift.jpg The volume of airborne drift from TWIN air assisted sprayer in a high wind speed of 8,5 m/s - is as low as the drift from the conventional sprayer at optimum spraying conditions (1,5 m/s). The tests were carried out over bare ground/short cut grass.


Comparison of Spray Drift from Different Air Assisted Sprayers

Original Article:
Comparison of spray drift from conventional field sprayer, Hardi TWIN, Kyndestofte Airsprayer and Danfoil. 
(Danish title: Sammenligning af afdrift fra konventionel sprøjte, Hardi Twin, Kyndestofte Airsprayer og Danfoil)
by: Jensen P.K. & Kirknel E. 1997. 14. Danske Planteværnskonference 1997. SP rapport nr. 7, 159-167.


  • Experiments carried out by the Danish Institute of Weed and Soil Sciences showed significant reduction of both airborne drift and sedimentation drift (fig a and b). Sedimentation is the fraction of drift that settles in the area next to the treated field.

  • The test took place in a stubble field without any canopy to catch air and droplets – this is the most challengeable condition for air assisted sprayers. As soon as the crop canopy develops, this will catch the spray liquid -and drift can be almost eliminated with TWIN air assistance.

  • When comparing different drift reduction techniques it is important also to focus on the spray quality (drop sizes) used. Most techniques rely on increased drop sizes for drift control, like twin fluid nozzles (John Deere, and AirTech) and air shear nozzles (Danfoil). Hardi TWIN is the only principle that offers efficient droplet control with out compromising on drop size.

Extracts from the report:


Fig.a  (above) shows that the use of TWIN air assistance with fine atomisation from F-01 reduced the drift remarkably compared to the same nozzle with out air and even compared to the larger F-025 nozzle.


Fig. b (above) shows that drift is reduced to less than half when applying air to the fine spray from a very small nozzle. On the first 5 m away from the target area Fine atomisation with TWIN air assistance controls drift better that Medium spray from a F-025 nozzle spraying conventionally.

The Kyndestoft Air air sleeve sprayer was not able to reduce drift - in fact the drift level turned out to be higher than when no air assistance was used. 

With the Danfoil (pneumatic nozzle / shear nozzle) the drift is at the same low level as with the TWIN, and this is a considerably better result than achieved in previous tests with the Danfoil. For this test the manufacturer changed the recommendations of air adjustment. The new recommendation implies that the atomisation is coarser and this less sensitive to wind. But at the same time it is an adjustment where the effect on e.g. weed control is not examined.

OBS: the original tests was done with the old HARDI 4110 nozzle series – in the text above the nozzles are changed to equivalent ISO nozzles.

Read the whole article (english) >>


Effect of Sprayer Speed on Spray Drift

by: H. Stallinga; J.M.G.P. Michielsen; P. van Velde; J.C. van de Zande. A&F Report, Wageningen The Netherlands April 2004


  • A very detailed test of airborne and sedimentation wind drift was made in order to conclude what influence driving speed (6 and 12 km/h), nozzle type (standard 04 and lowdrift 04) and TWIN air assistance has on drift. When spraying with lowdrift, an end-nozzle was fitted at the end of the boom on order to cut off the spray swath efficiently.

  • All spraying was done over a potato crop, drift measurements were samples from a strip of bare ground next to the sprayed potatoes.

  • Even at 12 km/h TWIN air assistance controls drift better than conventional at 6 km/ha and also better than lowdrift nozzles at 12 km/h (fig a).

  • To be sure that the drift sedimenting next to the field is less than 1% the conventional, lowdrift and border-nozzle needs a buffer zone that is two to three times wider than what is needed when using TWIN air assistance (Fig b).

Extracts from the report:


Fig.a: shows how big a dose rate ends up over the area close to the sprayed crop (1-5 m away from treated area). TWIN air assistance offers just as good or better drift control when using coverage efficient smaller droplets from conventional nozzle (XR) than is possible if increasing drop size with a low drift nozzle and using end-nozzle.


Fig.b: To be sure that the buffer zone catches all drift resulting in “dose rates” above 1% on the ground next to the field, conventional, lowdrift and and nozzle techniques need 2-3 times wider buffer zones compared to TWIN air assistance.

Link to full paper >>


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