PCC Nov/Dec 2019

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