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.


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