Nozzle outputs respond to nozzle design and tank mix

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Group of men standing under a boom sprayer

(From left) Tim Callaghan from WJ Matthews, Greg Gilblet from Agrimax Consulting, Scott Jameson from McIntosh Distribution, farm manager Tim Chaffey from ‘Red Bobs’ in Gunnedah, NSW, and Jon Bent from McIntosh Distribution assessing spray deposits for army worm control in a barley crop near Gunnedah.

PHOTO: McIntosh Distribution 

Yellow spray nozzle

A TeeJet TTJ-60-110-02 nozzle used in the experiment. The spray quality moved from medium to fine at 3.5 bar pressure with the addition of the oil. However, there was also less variability between the TTJ60 110-02 nozzles tested when oil was added, compared with water alone.

PHOTO: J. Connor Ferguson

The tank mix can impact on spray quality and nozzle uniformity
in unexpected ways, with the response often varying according
to the design of the nozzle selected

GRDC-funded research at the University of Queensland (UQ) has highlighted how different types of 015 and 02 orifice nozzles can respond to changes in tank mix.

One area of research looked at how tank mix can affect droplet size and the uniformity of the spray output when different nozzle designs are used (Table 1).

The studies showed that differences in nozzle outputs can occur when different tank mixes are used, particularly when compared with those published in the manufacturer’s nozzle charts, which are normally based on spraying only water.

Yellow spray nozzle

A Hardi Minidrift Duo 110-02 nozzle used in the experiment produced the least variation in the VMD when the tank mix was changed.

PHOTO: J. Connor Ferguson 

Many of the nozzles performed as expected by producing coarser droplets when a tank mix including pinoxaden
and a methylated oil was used, compared with just water only.

However, not all nozzle designs tested behaved this way. For example, the TeeJet TTJ60-110-02 operated at 3.5 bar pressure produced a finer spray droplet size with the same tank mix when compared with water only. (This result is most likely related to the specific design of this nozzle and should not be extrapolated to suggest all twin nozzles will behave this way.)

One of the most uniform nozzles tested was the Hardi Minidrift Duo 110-02, which is also a twin nozzle.

Standard deviation in the range of Dv0.5 (volume median diameter (VMD)) values (Table 2) was used to demonstrate the variability between nozzle types when different tank mix solutions are sprayed through them.

Lower average standard deviation values indicate that the Dv0.5 (VMD) remains more uniform when the tank mix is changed. This means the nozzle is more likely to produce a consistent output across a range of tank mixes.

Larger average standard deviation values indicate larger changes in droplet size when the tank mix changes, which may require spray operators to carefully consider how and when to use such nozzles.

The UQ studies were conducted in highly controlled conditions in a wind tunnel using a laser diffraction particle-size measurement system that has shown an accuracy (or repeatability) within three per cent.

The trials showed the drift-reduction capacity of many of the nozzles classified as very coarse and larger tended to be less affected by changes in the tank mix, whereas the droplet sizes produced by some of the nozzles that are classified by the manufacturer as medium spray qualities could become either coarser, or finer, depending on the tank mix.

Spray operators need to take into account that changes in product or adjuvant rate, mixing parameters, application volume or operating pressure under field conditions may produce different results to those reported here.

The UQ research has highlighted the need for operators to be able to access specific information about the impact of the tank mix on various nozzle types, especially in relation to drift potential and efficacy impacts.

Table 1 Volume median diameter (VMD, or Dv0.5) in micrometres (μm) and spray quality classification for a range of nozzles operated at 3.5 bar, using water and two herbicide tank mixes.
Nozzles tested
(at 3.5 bar)

 Water  Clopyralid  Pinoxaden + methylated oil
 Dv0.5 (μm) Spray quality   Dv0.5
(μm)
 Spray quality  Dv0.5
(μm)
 Spray quality
 TeeJet XR 110-03 (reference)  218  F  223  F  248  M
 Hypro Guardian Air 110-02
 336  M  349  C  362  C
 Lechler ID 120-02  572  XC  474  VC  436  C
 TeeJet TTI 110-015
 773  UC  650  XC  630  XC
 TeeJet TTI 110-02
 743  UC  667  UC  635  XC
 TeeJet TTJ60 110-0 287   M  262  M  211  F

Dv0.5 or VMD is the droplet size (diameter in micrometres or μm) at which half of the spray volume produced by the nozzle will exist as droplets smaller than this size, and the other half will exist as dropets larger than this size.

SOURCE: University Of Queensland Centre For Pesticide Application And Safety 

Table 2 Variation in the Dv0.5 (VMD) produced by selected low-drift nozzles* operated at 3.0 bar, expressed as the standard deviation +/- from the Dv0.5 (VMD) in micrometres (μm) for three spray solutions.

 Nozzles tested
(operated at 3.0 bar)
 Water  Clopyralid Pinoxaden
+ methylated oil
 
Average standard
deviation
 Standard deviation + / – micrometres (μm)
TeeJet XR 110-03 (reference) 7.33 4.69 4.45 5.49
Bellericay Bubblejet ABJ 110-015 28.62 26.01 14.52 23.05
Bellericay Bubblejet ABJ 110-02 9.60 5.11 3.54 6.08
TeeJet AITTJ60-110-02 8.40 8.72 9.78 8.97
TeeJet AIXR 110-015 5.44 10.28 9.06 8.26
TeeJet AIXR 110-02 19.63 16.40 12.80 16.28
Hypro Guardian Air 110-015 15.92 14.27 10.61 13.60
Hypro Guardian Air 110-02  6.14 8.17  8.73 7.68
Lechler IDK 120-02 4.64 6.35 4.84 5.28
Lechler IDKT 120-02 6.32 8.23 4.29 6.28
Hardi Minidrift MD-110-02 4.16 3.73 3.10 3.66
Hardi Minidrift Duo-110-02 5.23 2.30 3.53 3.68
TeeJet TTI 110-015 13.04 10.51 14.04 12.53
TeeJet TTI 110-02 5.39 8.71 12.25 8.78
Teejet TTJ60-110-02  41.71 11.69 5.83 19.74
Hypro ULD 120-015 7.75 14.11 8.54 10.13
Hypro ULD 120-02 7.63 3.39 3.89 4.97

*The range of nozzles listed in this table does not include all of the nozzles tested by J. Connor Ferguson. 

Dv0.5 or VMD is the droplet size (diameter in micrometres or μm) at which half of the spray volume produced by the nozzle will exist as droplets smaller than this size, and the other half will exist as dropets larger than this size.

SOURCE: University of Queensland Centre for Pesticide Application and Safety

More information:

J. Connor Ferguson,
University of Queensland,
0402 094 483,
j.ferguson@uq.edu.au

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