Spraying with Twin Angles
Using flat fan nozzles with an angled twin spray pattern can overcome the compromised coverage caused by the deflection forces of driving speed.
Application speed has an important influence on droplet trajectory. The coarser the spray quality, the more important this factor becomes as larger droplets have more initial momentum and greater velocity.
Traditional flat fan nozzles face vertically downward. During application the force from the driving speed deflects the downward oriented droplets forward. Consequently, when the target area is reached the droplet trajectory is forward orientated. The higher the speed the more pronounced the effect. The coverage of the back site of target plants is always compromised under these circumstances. In herbicide knockdown, pasture and fallow situations this is not an issue but particular post-em applications with fungicides and insecticides can suffer from insufficient plant coverage.
Hollow cone nozzles have a fit in these situations at very low speeds. However, there are a number of flat fan nozzles with an angled twin spray pattern available to overcome this problem more efficiently, eg. TurboDrop HS (link) or the Albuz CVI Twin (link).
These nozzles produce a Twin fan, one directed forward and the other directed backwards. If the backwards speed of the droplet is larger than the forward speed of the boom, the droplet has a good chance to hit the back of the plant, while droplets from the forward orientated fan will hit the front of the plant.
Unfortuanally the speed of droplets is not very high and consequently the driving speed has to be slow.
The most versatile angle set-up for speeds up to 10 km/h (max 12 km/h) consists of a twin cap nozzle body (link) that can be fitted with AirMix nozzles and conventional XR nozzles, or any combination of them. By alternating their forwards/backwards position on the boom both fans produce COARSE and FINE droplets. Like with most other angled nozzles, the backward orientated angle is only 30⁰ and therefore too low to overcome the forward driving orientation at higher speeds.
The agrotop TurboDrop HS has a 50⁰ backwards oriented fan and can overcome speeds up to 15 Km/h (max 18 km/h).
Angled nozzles have a very good fit in vegetable crops (especially onions!) and for fungicide/insecticide application in Broadacre crops (especially cereals!).
They allow the operator more operational flexibility compared to using FINE droplets yet provide similar efficacy.
- Twin angle nozzle work principally best with bigger droplets
- To make it work the driving speed has to be relatively slow
- Excellent for fungicide/insecticide boom applications. Keep the water rate up (= 100 L/ha)