Wednesday, June 1, 2011

New Nozzles!

We re-nozzled the tunnel sprayer to obtain greater flow per nozzle with a lower pressure.  Specifically, we changed to TeeJet AITX ConeJet Air-induction Nozzles (AITXA8003VK).  At 100 psi, these put out 0.467 gpm, so for 16 nozzles the output was 7.5 gpm or, in our case, 95 gallons per acre.

Results were spectacularly better.  Even with a reasonably strong breeze parallel with the row, there was virtually no drift.  Further, 21 out of every 95 gallons applied per acre were recaptured, giving a final dilute application of 74 gallons per acre for full coverage.

Tuesday, May 17, 2011

More Calibration

After the previous session with the tunnel srayer and the airblast sprayer, it was clear that we were getting better coverage with the airblast.  This was puzzling, since our calculations suggested that they should have been applying the same amount of water, and there was considerably more drift with the airblast.  On May 17, we measured actual flow from the nozzles.  The airblast nozzles put out the correct volume of water, but the tunnel sprayer nozzles only put out 1/5 of the projected quantity.  We used a nozzle chart from the company that had everything in English units.  Apparently, there is an error in this chart.  When we used their metric chart and converted to English units, we got the correct flow.

Unfortunately, we needed to increase pressure to 300 psi to obtain our desired flow, 100 gallons per acre (or about 7.8 gallons per minute).  This high pressure resulted in small droplet size which drifted more than desired.

So, our next steps will be to change nozzles to ones that would give adequate flow at lower pressure.  Also, we will test air-induction nozzles in the sprayer to determine the effect of larger droplet size.

Friday, May 6, 2011

Adjustments to the Tunnel Sprayer and Comparison with Airblast

On May 2, we took the tunnel sprayer out again. This time, we adjusted flow rate out of the nozzles to match the dilute gallonage of the trees being sprayed, about 100 gallons per acre (13' row spacing and 3 mph = 7.8 gallons per minute spread across 16 nozzles -- the top two on each side were shut off). We also narrowed the tunnel to reduce the impact of wind blowing through it.

As with last week, there was a reasonably stiff breeze from the south, parallel to the row, so the wind blew into the back of the sprayer in one direction and into the front in the other direction. With the reduced flow, we saw less drift out of the tunnel than last week, but some drift still occurred. We also fired up an airblast and calibrated it also to spray 100 gallons per acre (7.8 gallons per minute). As you will see from the following video, drift was much greater with the airblast. Coverage, however, appeared better with the airblast than the tunnel. I know that this observation doesn't make sense. Next week, we will measure actual nozzle output (with some of Jon Clements' sprayer calibration equipment) and not rely on the charts and on our calculations.

Saturday, April 30, 2011

Maiden Voyage of the Tunnel Sprayer

April 27, 2011:

We hooked up the tunnel sprayer and ran it for the first time over trees.  All worked remarkable well.

1.  The sprayer certainly is tall!
2.  It is much much quieter than an airblast.
3.  It is not easy to manage behind the tractor and will require some adjustments and practice.
4.  We had a significant wind parallel with the row direction -- with these trees with very few leaves, spray material was blown out of the sprayer.  Drift was limited to the row being sprayed, for the most part.

Next week, we will begin to assess coverage and spray material usage in comparison with standard airblast application.