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VINEYARD REVIEW<br />
This pump pre-filter was so full of sulfur and oil<br />
that it couldn’t be easily removed. It came lose<br />
after an overnight soak with a tank cleaner. No<br />
wonder the pressure had low-impeded flow!<br />
Photo courtesy of F. Niederholzer<br />
Continued from Page 32<br />
2. Check your calibration<br />
variables to make sure they are<br />
accurate. Calibration is an essential<br />
part of sprayer efficiency. I<br />
prefer to use the basic calibration<br />
formula, which works with any<br />
sprayer and is easy to remember.<br />
Spray volume<br />
(GPA, gallons per acre)<br />
No matter what formula you choose<br />
to use to calibrate, the variables<br />
you need to measure are the same:<br />
nozzle output, tractor ground<br />
speed, and spray swath width.<br />
Nozzle output (flow rate) is a function<br />
of the pressure and the type of<br />
nozzle. You can check this in the<br />
nozzle manufacturer’s catalog-most<br />
are available online. But you should<br />
also confirm by measuring the flow<br />
rate because the output can change<br />
when nozzles wear, or when the<br />
pressure differs from that listed in<br />
the catalog. I’ve found that even new<br />
nozzles can have flow rates that differ<br />
significantly from what is expected.<br />
To measure the entire sprayer<br />
flow rate, follow these steps:<br />
▶<br />
=<br />
Park the sprayer on a level surface.<br />
Fill the tank with clean water up<br />
to a verifiable spot at the top of the<br />
tank—usually you can see a line at<br />
the strainer or even make a mark<br />
with a Sharpie.<br />
▶ Working with the driver, bring<br />
the PTO or engine up to operating<br />
RPMs (540) and open all<br />
the nozzles while timing with a<br />
stopwatch how long they are open.<br />
▶<br />
Flow Rate<br />
(GPM, gallons per minute)<br />
Land Rate<br />
(APM, acres per minute)<br />
You’ll want to keep them open for<br />
a minute or two. Check to confirm<br />
the pressure while they are open<br />
(you’ll need to wear PPE, personal<br />
protective equipment, because<br />
you’ll get wet!). Be sure to stop<br />
your stopwatch when the nozzles<br />
are shut off and use that time for<br />
your calculation.<br />
Refill the sprayer up to your line<br />
and record how much water it<br />
takes to refill. Be sure to use a<br />
bucket that has been calibrated<br />
itself to make accurate measurements.<br />
Then divide the number of<br />
gallons it took to refill by the time<br />
to get the gallons per minute.<br />
This method gives you output of the<br />
entire sprayer, all nozzles. If you<br />
want to measure individual nozzle<br />
flow rates, you will need to either<br />
make or purchase a nozzle adapter,<br />
to fit over the nozzle with a hose<br />
attached to capture the flow. We’ve<br />
made an adapter from dishwasher<br />
plumbing supplies, brass hose bibs<br />
and hose clamps. AAMS Salvarani<br />
manufacturing in Belgium is a<br />
source to purchase nozzle adapters.<br />
Once you have the actual sprayer<br />
flow rate, confirm your tractor<br />
ground speed. Don’t rely on the<br />
tractor speedometer, these are<br />
notoriously erroneous as they<br />
are typically set with the tires<br />
at the place of manufacturing.<br />
When tire sizes are changed, as<br />
they often are once the tractor<br />
reaches the sale point, the number<br />
of rotations and corresponding<br />
speedometer mph will be affected.<br />
To check the tractor speed, measure<br />
out at least 100 feet in the<br />
terrain you’ll be working in, note<br />
the tractor gear and setting, and<br />
time the travel. This is typically in<br />
seconds, so you’ll need to convert<br />
to distance travelled over time in<br />
minutes to get feet per minute.<br />
Land rate is defined as the swath<br />
width in feet multiplied by the<br />
ground speed in feet per minute.<br />
Swath width in orchards and<br />
vineyards is the row spacing, in<br />
feet. From the square feet, or area<br />
sprayed, you can then do the conversions<br />
to acres sprayed per minute.<br />
Continued on Page 36<br />
34 Progressive Crop Consultant <strong>Nov</strong>ember / <strong>Dec</strong>ember <strong>2019</strong>