This is a guest post by Tom Wolf of Agrimetrix Research and Training.
Spray15 is here, but are you ready? Here are the top 5 tips
and tricks to give you a productivity edge:
1. Choose a spray pressure in the middle of your nozzle’s operating range.
All spray nozzles have a range of pressures throughout which the manufacturer believes the spray pattern is acceptable. We’ve come to assume that the correct spray pressure for a nozzle is about 40 psi, largely becauseof tradition. In fact, 40 psi is merely the mid-point of a traditional
nozzle’s pressure range, between 20 and 60 psi.
Modern air-induced nozzles have much higher and wider pressure ranges, usually from 30 to 100 psi. The new middle ground is about 70 psi. Why so high? There are two reasons. Air-induced tips perform optimally at higher pressures, and remain lower drift than conventional nozzles even at those pressures. The second reason is travel speed range.
As a sprayer changes speed, the spray pressure is automatically adjusted to maintain a constant application volume. Even a small reduction in speed, due to changes in terrain, for example, can put the spray pressure too low for good nozzle operation. A nozzle that is sized for a higher average operating pressure will permit a reduction in speed without a nozzle performance penalty at lower speeds.
2. Measure your boom’s pressure drop and add this value
to your target operating pressure.
All sprayers experience a drop in pressure as the solution moves further away from the pump. This is due to friction caused by a number of factors, including length of tubing, elbows, valves, screens, and other flow obstructions. The pressure transducer that reports pressure to the cab
is usually located between the pump and the manifold that divides the spray into the various boom sections. After this point, the spray liquid experiences significant additional flow restrictions, and pressure at the nozzle will usually be lower than the cab reading indicates.
The nozzle pressure can be measured with a gauge placed on a nozzle body. Simply purchase a gauge and a threaded nozzle cap, combine the two and install in place of a nozzle. Operate the sprayer and read this pressure, comparing it to the pressure in the cab. The difference between the two is the pressure drop. Do this for your lowest, as well as
your highest expected flow rates. Higher flow rates cause greater pressure drops. If you want to spray at 60 psi and your pressure drop is 10 psi, then the cab pressure should read 70 psi.
3. Install a clean water tank and wash-down nozzle on your sprayer.
One of the more time-consuming aspects of a spray operation
is cleaning the sprayer when you switch products. The best way
to clean a sprayer quickly is to accurately calculate your last tank needs, and spray any remainder(if you’ve done your math, this will be small) out in the field.
Depending on the product, overspraying the crop a second time
can be an option, simply reduce the application rate to prevent doubling the dose. When the spray tank is empty, introduce clean water from your saddle tank through the wash-down nozzle and continue spraying.
The spray mixture will quickly become increasingly dilute and flush through all sprayer parts that contained the product. The clean water tank can contain a cleaning adjuvant such as ammonia or a detergent depending on the properties of the product to be removed. After the sprayer is cleaned, stop and inspect all screens to ensure there are no pockets of residue.
4. Obtain a faster transfer system and strive to load faster.
Most sprayer refills can take longer than planned, and before you know it, 15 or more minutes have passed. That can be a significant portion of the total spray time, resulting in lost productivity. By moving to a 3” transfer pump and plumbing, fills in 5 minutes are possible. Care is required to
ensure that products are properly mixed, and dry products may
need to be hydrated in advance to prevent screen and nozzle plugging.
The fastest operators have a capable person on the tender truck, and have the tender truck move to the sprayer at the field edge, not the other way. Front fill attachments save further time. Think of it like a Nascar pit stop, and watch productivity increase.
5. Say goodbye to boom end valves.
Traditional 1” wet boom sections have a “boom end” that is capped about 4 to 6” beyond the last nozzle body. The boom end is a dead end, and any pesticide mixture that ends up there, as well as any air in the boom, is virtually impossible to remove.
Two problems result: the residue can cause contamination issues. The air in a boom acts as a bladder, preventing diaphragm check valves from shutting nozzles off until enough liquid has left the boom to reduce the bladder pressure.
The most common way to remedy this is to install valves at each boom end, flushing the air and contamination out. But this has to be repeated twice for each boom section, which can number anywhere from 5 to 11 per boom. A product called the Hypro Express Nozzle Body End Cap automates the process. The cap has a novel design that eliminates the dead reservoir and bleeds air from the boom continuously during normal operation. The result is easier sprayer cleaning and better shutoff responsiveness.
Spraying is an important operation, and timing is critical. Small changes in productivity can add up, preventing problems and getting more acres treated each day.
For more information, contact Tom Wolf of Agrimetrix Research & Training at firstname.lastname@example.org.