Category: Boom Sprayers

Main category for sprayers with horizontal booms

An Easier Way to Clean Your Sprayer
Farming can be divided into pleasant and unpleasant tasks. Seeding is pleasant. Hauling oats or barley not so much. Sprayer cleaning is…not. And yet it’s the unpleasant tasks that are often the most important. How can we make them better?
We all know the need for a properly cleaned sprayer. Herbicide residue can harm a sprayed crop, and the damage might not show up for over a week. When it does, it usually takes a while to identify the symptoms and damage patterns to be sure. And then we wait for the inevitable yield loss.
It wasn’t long after the introduction of the Group 2 Mode of Action that producers started noticing how even small residues of these products in sprayer tanks could damage crop yields, most noticeably canola, but also other broadleaf species.
Thirty years later, the problems persist. Let’s look at ways of preventing them.
Cleaning a sprayer is a lot like doing the dishes. Using the right detergent, soaking the hard stuff, being thorough, and rinsing properly – they all matter.
It all starts, though, with preventing the problem.
The main culprits that cause sprayer contamination have the following properties:
- They are typically dry formulations,
- they typically have poor water-solubility, and
- they are potent in low doses.
Many products in herbicide Group 2 MOA fit that bill. The ones that rise to the top of the list have an additional characteristic:
- poor solubility at low pH.
As a subgroup within the Group 2 MOA, the sulfonyl ureas are a top concern, with products like Refine, Express, and Ally on the most-wanted list. Another problem subgroup is the triazolopyrimidines, containing products like Frontline and Simplicity, which, like the SUs, have very pH-dependent solubilities (better solubility at higher pH). Other Group 2s have fewer issues. Everest and Varro have good overall water solubility, for example. The solubility of imidazolinones like Odyssey, Pursuit, Raptor increases with low pH. We tend to see fewer problems with these products.
Instances that add to the problem involve tank mixing with weak acid herbicides, including glyphosate, but especially those that are formulated as emulsifiable concentrates (oils, EC), appearing milky when mixed with water. Most of our herbicides are weak acids.
Two problems occur with these:
- The weak-acid herbicide lowers the pH of the spray mix, possibly reducing the solubility of the problematic Group 2s.
- Then, oily formulation can adhere the herbicide to plastic and rubber sprayer parts such as tanks, connectors, and hoses.
The best advice on preventing a cleanout problem, is, therefore, to make sure the product is fully dissolved or suspended. Proper mixing technique and time are the key components. Some products, like Simplicity, can benefit from a pH increase (adding ammonia) prior to mixing the product.
Once properly mixed, we can still have problems at the screens. Dry formulations require a screen mesh of 50 or coarser according to their labels. But many sprayers contain 80 mesh screens, some even have 100 mesh. All screens should be inspected both before, during, and after spraying these products. Screen residues cause longer-term contamination, and their cleaning is an important part of this whole process.
After spraying, the cleaning process relies on three main things:
1. We need to remove as much of the problem mixture as possible.
2. We need to dilute the remainder as much as possible and use it to clean the boom plumbing.
3. Ensure anything that came in contact with spray mix has been cleaned.
Removing the mixture
The best way to remove the remainder is to spray it out in the field you’ve just treated. You can overspray some products again, or if you have any land set aside it can be used for this purpose. It’s never a good idea to drain the tank on any land. Obviously, some experience and math is helpful to make sure the last tank empties nicely on the field.
Diluting the remainder
The next step is to dilute the remainder, using tank cleaning adjuvants like ammonia (this raises the pH and helps remove those products whose solubility benefits from this) and detergent (this removes the oily layer formed by EC formulations). Commercial cleaners like All Clear or Cleanout combine these properties in one jug.
Diluting is most effective when done in multiple smaller batches, as long as we can ensure the tank walls are reached. Wash-down nozzles installed in the tank can do this for us.
Let’s assume the sprayer has a 150 gallon clean water reservoir. It’s tempting to empty the whole thing into the tank. We can calculate the diluting power of this: if we had a 10 gallon remainder in the tank and added 150 gallons water, the remainder would be diluted by a factor of 16. After spraying this out, we’d then have to re-fill the rinse tank if we wanted to do more.
If we rinsed in two 75 gallon batches (add 75 gallons, agitate via wash-down nozzle, spray out, repeat), we would dilute by a factor of 72. If we did three rinses of 50 gallons each, our final dilution factor would be 216. That’s the same dilution as adding about 2150 gallons to the first 10 gal spray tank remainder, and is about 14 times better than dumping the whole 150 gallons in at the beginning!
An improvement in diluting power can be achieved by adding a separate clean water pump. Introducing clean water to the tank as rinsate is sprayed out the boom reduces water use even further.
Cleaning all spray mix contact points
The last step is to pay attention to the things you can’t see: Screens, boom lines and boom ends. The total interior surface area of black rubber boom hoses on a 100 ft sprayer with 7 sections can be as much as several square metres, and this surface can bind residues. Seven sections, each with boom ends, can hold several gallons, as well as accumulated debris. Scrubbing screens, soaking boom lines, and flushing boom ends is the necessary detail that this job requires.
A few final pointers:
- Adding a surfactant or a commercial cleaner can generate a lot of foam. Have de-foamer handy, it will save a lot of frustration.
- A bucket helps collect and clean screens and nozzles.
- Consider upgrading to more steel components on your next sprayer – tanks and booms. Stainless steel cleans faster than plastic.
- Install a way to flush your boom ends. Traditional ball valves do the job, but Hypro’s Express Nozzle Body End Caps do it automatically. These inexpensive units eliminate the dead space in boom ends and as a bonus, bleed air from the lines on the go.
Hypro’s Express Nozzle Body End Caps on a short length of stainless boom.
Done well, sprayer cleaning doesn’t have to be unpleasant. And it certainly results in a better night’s sleep.
May 21, 2015

Increase Sprayer Productivity Without Driving Faster

Timing trumps most things in crop protection. A great spray applied at the wrong time isn’t nearly as valuable as a mediocre spray at the right time. So how do we improve our ability to get things done at the right time?

Often, we try to win races by driving faster. In our last article, we looked at driving speed and concluded that faster speeds can lead to more drift and less uniform deposition. Driving slower can be viewed as a sort of insurance policy: You may not notice the benefits right away, but on days when that extra bit of performance is required, you’re covered.

So how do you get the job done quickly if you can’t drive faster? To answer, we have to look to other opportunities for boosting productivity.

Recently, we built a model to capture all the elements of a normal spray operation that affect timeliness. These were:

travel speed
boom width
tank size
water volume
field length
number of headlands
turning speed
fill time

First, we identified a reasonable base condition. For the sprayer, that was a travel speed of 14 mph, a 90’ boom, an 800 gal tank, a 10 gpa water volume, and a 20 minute fill time. Then, we set up a typical field situation, which was spraying a half-mile run on a quarter with two sprayed headlands and a turning speed of 8 mph. Finally, we changed one factor at a time to determine its relative importance.

Before we discuss the results, let’s make it clear that just because changing some of these factors improves productivity doesn’t mean we’re recommending them! For example, adequate water volume remains an important input that improves coverage and permits the use of low-drift sprays. Larger tanks increase compaction and take more power, and so forth.

Here’s what we found:

All productivity values were expressed as acres per engine hour. For this reason, our numbers will be lower than what a typical sprayer monitor reports, most of which calculate acres per spraying hour.

For the base condition, the sprayer spent 15% of its driving time turning, and 37% of its on-field time stationary (i.e. filling). For every hour spent on the field, less than half the time (48%) was spent spraying. This resulted in an average productivity of 82 acres/h.

Increasing the spray speed to 18 mph increased average productivity to 93 acres/h, but it also increased the proportion of time spent turning and loading, resulting in just 40% of the field time spent spraying.

Decreasing the loading time from 20 to 10 minutes reduced the proportion of field time spent stationary to 23%, covering 100 acres/h at 14 mph. Surprisingly, this was the productivity-winner, resuling in 62% of on-field time spraying.

We discovered other powerful productivity factors, and chief among them was boom width. A 33% increase in boom width from 90’ to 120’ gave a productivity boost to 94 acres/h, close to the same result as increasing the travel speed to 18 mph earlier. Similar side effects occurred: more time turning, and a greater proportion of time filling, as we saw with faster travel speeds.

Boom width seems to have some room for growth. Many smaller European counties use wider booms than we do in North America, for example. With gps guidance and large fields, we have excellent conditions for their implementation.

Two other factors that had similar effects to fill time were water volume and tank size. Less water and larger tanks increased productivity by decreasing the fill frequency, with effects similar in magnitude to speeding up the fill time. Decreasing the water volume from 10 to 5 gpa increased productivity to 100 acres/h by decreasing the proportion of time the sprayer was stopped from 37% to 23%. Increasing from an 800 to a 1,200 gallon tank increased productivity to 94 acres/h, again by decreasing the proportion of time spent filling to 28%.

Taken together, a sprayer with a 120’ boom, a 1,200 gal tank, applying 10 gpa and filling in 10 min had an average productivity of 132 acres/h. And this was achieved without driving faster than 14 mph. If you can string two quarters together and drive a whole mile before turning, that number rises to 145 acres/h, a surprisingly large 13 acres/h gain.

The perspective of minimizing downtime extends to other tasks, too:

Be more prepared for the job by reviewing the product label in advance, noting the correct mixing order.
Keep extra nozzles, clamps, and nozzle bodies in the cab.
Don’t clean plugged nozzles, replace them.
Use low-drift nozzles so a small increase in wind doesn’t shut you down.
Ensure all the products needed are on the tender truck (e.g. pesticide, adjuvant, tank cleaner, anti-foamer, etc.).
Consider switching to 3” plumbing (pump rates of 300 – 400 gpm are possible).
Make sure your inductor won’t be the limiting factor. For example, product pumps can be awfully slow when the product is cold. It might be worthwhile to explore a venturi system.

Speeding up the fill process is a good idea, but be careful with certain products. Dry materials such as the sulfonyl ureas (e.g. Refine, Express SG, etc.) and some fungicides (e.g. Astound, etc.) require time to hydrate in water so they mix properly. Some operators pre-hydrate these in a smaller tank, while others get an extra tank to pre-mix whole loads and simply transfer them over.

Also think about the time spent cleaning the sprayer. Thoroughness is important, but perhaps there are efficiencies to be gained there as well, like never letting a sprayer sit after spraying. We’ve written about continuous rinsing, for example, to improve cleaning speed and effectiveness.

So, the quicker we can spray, while ensuring a quality job, the more effective our crop protection practices will be. We encourage you to use our to determine your best configuration.

Got a productivity tips to share? Let us know! And remember: In spraying, the race is won in the pits.

Factor	Base	Drive Faster	Fill Faster	Spray Wider	Less Water	Bigger Tank	New Sprayer
Travel Speed	14 mph	18 mph	14 mph	14 mph	14 mph	14 mph	14 mph
Fill time	20 min	20 min	10 min	20 min	20 min	20 min	10 min
Boom Width	90 ft	90 ft	90 ft	120 ft	90 ft	90 ft	120 ft
Water Volume	10 gpa	10 gpa	10 gpa	10 gpa	5 gpa	10 gpa	10 gpa
Tank Size	800 gal	800 gal	800 gal	800 gal	800 gal	1200 gal	1200 gal
Field Length	0.5 mile	0.5 mile	0.5 mile	0.5 mile	0.5 mile	0.5 mile	0.5 mile

Time Turning	15%	19%	15%	20%	15%	15%	20%
Time Loading	37%	42%	23%	42%	23%	28%	19%
Time Spraying	48%	39%	62%	38%	62%	57%	61%
Acres/h	82	93	100	94	100	94	132

May 21, 2015

How Fast Should I Drive My Sprayer?
It seems simple: The faster you drive the sprayer, the more area you cover. This makes higher travel speeds a seductive method for improving productivity. Sprayer manufacturers knew this 25 years ago when pull-type sprayers first received bigger, suspended outrigger wheels. Since then they’ve delivered more powerful engines, better hydraulic motors, smoother suspension and cruise control.
Each of these innovations still required the operator to consider the relationship between travel speed, pressure, nozzle choice and the desired output per acre. But now we have rate controllers, and we don’t have to think about such mundane things anymore… do we? Do we still do a good job if we go faster? What exactly happens when we speed up?
Before considering the role of the rate controller, you have to decide on an overall target-speed range. Charts, apps, or online tools can help you select nozzles sized to deliver your application volume at a given speed and pressure. This initial travel-speed decision requires an understanding of how spray gets delivered to the target. Let’s start with the spray boom.
As the boom moves through air, the oncoming air does three things to the spray:
- It shears the spray, making it a bit finer.
- It scrubs the smallest droplets from the pattern, leaving them in the wake of the boom.
- Finally, negative pressure behind the pattern sucks even more fine spray into the sprayer wake.
Collectively, these create the dreaded “spray plume” that hangs behind the spray boom… and we’ve lost control over it. The faster we move, the greater the proportion of the spray that ends up in the plume. This can be anywhere from one to 15% of the spray. Once formed, that plume moves with the prevailing winds.
Today’s sprayers have wide booms, and faster speeds often require us to keep these booms higher than we have in the past to prevent impacts. But higher booms reduce our control over the spray’s direction. For example, when spraying vertical targets (e.g. wheat heads) we have begun to employ angled sprays. But droplets lose momentum quickly. The further they are from the target, the more likely they are to slow or even fall vertically before they reach the target. That means that higher booms often negate the benefit of angled sprays.
Still not convinced of the perils of high speeds? Well, think about the aerodynamics of the sprayer itself. As travel speed increases, the sprayer, the boom, and even the spray pattern itself disrupt the air around it. Visualize a sprayer in a wind tunnel with smoke tracer lines. The nice pattern created by the boom gets really messy in a turbulent environment. This can cause a loss of deposit uniformity, resulting in a reduction of overall effectiveness.
So far, we’ve talked about average speeds – choosing to travel eight, 12 or 16 mph overall, and then choosing the nozzle that will suit. Now let’s talk about changes in your travel speed within your target-speed range.
Operators know that even small travel speed changes can result in large pressure changes. That’s because travel speed and pressure enjoy a “square-root relationship”. If you double travel speed, your rate controller needs to quadruple the spray pressure to meet the new flow need!
Even minor changes in speed (to adapt to field conditions) can lead to big fluctuations in pressure, changing average droplet size, and affecting coverage and drift potential. Severe pressure fluctuations are more likely with a faster average travel speed. That’s perhaps why pulse-width modulation, which decouples spray pressure from travel speed and replaces it with a solenoid duty cycle, has a growing role in fast self-propelled sprayers.
To minimize pressure fluctuations, use the pressure gauge as your speedometer. Have the boom pressure displayed prominently in your sprayer cab, and try to operate at speeds that result in a pressure which is optimal for the job you’re trying to do.
So, let’s summarize the effects of fast travel speeds.
Pros:
- More area covered per hour
- Better contact with vertical targets (if the booms are kept low)
Cons:
- More drift
- Less uniform deposition
- Wider pressure fluctuations
So, how fast is too fast? We won’t draw a line in the sand, but we will emphasize how important it is to consider as much information as you can before deciding on a travel speed. Don’t rely on the rate-controller to think for you – it doesn’t have all the information.
May 21, 2015
Water Sensitive Paper for Assessing Spray Coverage
Water Sensitive Paper
Water-sensitive paper is a useful tool for assessing spray coverage. Here are a few tips for making it work for you.
Water-sensitive paper is manufactured by a number of companies, including Syngenta, Spot On, and WS Paper and is available for purchase (see here for comparisons). The papers are a useful tool for helping calibrate aerial and ground sprayers because spray deposition becomes visible immediately after spraying. With the proper equipment, droplet size and coverage can be estimated from scanned images.
Simply place the paper on or near the target of interest. On most cases for herbicide application, it can be placed on the ground. It can also be attached to leaves or stems using paperclips.
When water comes in contact with the paper, it turns blue, and spray droplets as small as 50 µm become visible. Avoid touching the paper with bare hands except from the edges – you’ll see your fingerprints. Wearing gloves helps if you plan to handle many of them. Wait for the paper to dry before storing or stacking.
If left exposed to air, they will soon turn completely blue from atmospheric humidity. The same will happen if stored in a plastic bag before they are completely dry.
To show how these cards can be useful for an applicator, we prepared 15 cards (five spray qualities at three water volumes each). They can be used as a guide to assess the quality of the spray job. As a start, aim for a Coarse spray quality, and use enough water to achieve coverage about in the middle of the matrix. Avoid low water volumes in combination with extremely coarse sprays.
These water-sensitive papers were sprayed under controlled conditions and they demonstrate the role droplet size plays in coverage. As the droplets get finer, there are more of them, increasing coverage. However, this is really only hypothetical as many drift off target before impinging. As the droplets get coarser, there are less of them, and coverage may be compromised. To compensate for this, higher volumes are used. Credit – Dr. T. Wolf, Saskatchewan.
This matrix can be used as a guide to assess approximate coverage of a spray under field conditions.
A high-res pdf of the matrix (in US units) can be downloaded here.
The metric version is here.
The spray deposits spread out after they hit the paper, and as a result the deposit diameter is about twice the actual droplet diameter. This ratio is known as the spread factor, and it must be known before an accurate droplet size measurement can be done. That’s easier said than done because the spread factor depends on the properties of the spray liquid (surface tension, for example), the diameter of the droplet, and also the humidity at the time of the trial. On humid days, the spread factor increases and in fact the papers may turn entirely blue just from exposure to that humidity.
A practical water volume limit for making an accurate measurement is about 10 US gpa or 100 L/ha. At higher volumes, the droplets coalesce and it’s hard to tell how many droplets for any given deposit.
May 20, 2015
Pulse Width Modulation
Note: This article was written before significant changes occurred in the marketplace in 2016. While it still explains how the system works, a more current account can be found here.
Pulse-Width-Modulation (PWM) refers to a method for controlling the flow rate of fluids. How does it work? Does it have a fit on your farm? We explain in this article.
Case Aim Command, Capstan PinPoint, Raven Hawkeye, TeeJet DynaJet, John Deere ExactApply, WEEDit Quadro, and Agrifac StrictSprayPlus are Pulse-Width-Modulation (PWM) technologies, where a pulsing solenoid controls flow rate through the nozzles. The solenoid is installed in place of the diaphragm check valve, and shuts off the nozzle flow for a split second exactly 10 times per second.
How it Works
All PWM systems employs the duty cycle of a pulsing solenoid instead of spray pressure to control nozzle output. The pulse width, also known as the duty cycle, is the proportion of time that the solenoid is open, and can range from 10% to 100%, although 20% to 100% is more realistic. Duty cycle is closely related to the nozzle flow. Pressure (and droplet size) stays fairly constant throughout the duty cycle range. This means that a wider range of travel speeds can be used without any change in spray pressure. Pressure can still be changed if necessary, to control droplet size.
The Tip Wizard
If using ComboJet nozzles, use the Tip Wizard to identify the best nozzle. Select “Canada”, and “US gal/acre”. Select “Tip Wizard” on the left side of the screen, and choose “Blended Pulse System, Search for Tips”.
Enter your information in the boxes. For example, 10 (gpa), 350 (µm, VMD), 15 (mph, max speed), 20 (inches nozzle spacing), 110 (degrees, fan angle). Always select 110 for use with Aim Command or Capstan.
Click “Search for Spray Tips”. The pressure that matches your droplet size criteria will be highlighted for each nozzle. In this example, the SR11006 nozzle is highlighted at 52 psi, giving about 349 µm VMD. If you choose the SR11008, the pressure goes up to 73 psi to get the same droplet size, and your minimum and maximum speeds increase as a result. Note that the numbers are calculated and do not always agree exactly with published nozzle charts. Allow for some leeway, and double check with manufacturer flow charts to be sure you’re in the ballpark.
If using TeeJet style bodies, use any wide-angle spray tip that is not air-induced. Good candidates are the TurboTeeJet, the TurboTwinJet, and the Hypro Guardian. Other pre-orifice flat fans can also be used.
Pressure Drop
Also note that the system should not be used at very high pressures – about 60 psi max. Finally, pay attention to the pressure drop across the solenoids. The manufacturer publishes charts that show the drop at various flow rates. For a 11004 tip, the drop is about 3 psi. For a 11008 tip, it’s between 6 at 30 psi and 13 psi at 60 psi. Add these values to your rate controller pressure reading, i.e., if you want to spray at 40 psi, have the rate controller read 40 & pressure drop.
Calculating Duty Cycle
Your expected average speed should be 60 – 80% of the maximum speed that the nozzle is capable of in these charts (100% duty cycle). For example, if you expect to travel 14 mph, select a solution whose maximum speed is 20 mph. This way, the system will be averaging 70% duty cycle at 14 mph (20 mph x 70% = 14 mph), allowing you to increase your application rate (or speed) by 30% where necessary (system moves to 100% duty cycle), or reduce your travel speed to 5 mph (system moves to 25% duty cycle). Slowing down further is an option, but a very coarse spray at low duty cycle may introduce skips under some conditions (low booms, fast speeds). This option also gives you maximum flexibility to change pressure to manage droplet size in both directions. Using a higher average duty cycle (say 80%) increases your flexibility to slow down, but limits your top speed more.
Picking the Right Droplet Size and Pressure
The right nozzle pressure depends on the choice of nozzle. For low-drift tips such as the Wilger SR and MR, higher pressures (>40) are recommended to ensure the spray pattern develops fully. Drift remains acceptably low. The %<200 columns in the Tip Wizard is a drift index. It identifies the proportion of the total spray volume in droplets <200 µm. Use the number to compare drift potential of various nozzles and pressures, making sure you also pay attention to the %<600 µm column. When values in that column are subtracted from 100, the result is volume in droplets >600 µm, an indication of the volume in droplets that are possibly too large to contribute much to coverage or efficacy.
It’s not easy to pick the best droplet size for each application because various pesticides and pests each have their own response. Typically, a Volume Median Diameter (VMD) ranging from 350 to 450 µm is ideal for most pesticides. Choose smaller VMDs for low water volumes, grassy weeds, and contact products, but use these only when drift is manageable. Choose larger VMDs for systemic products, broadleaf weeds, and higher water volumes, or when drift must be avoided. If you aim for 375 µm to start, that will be relatively low-drift and work well for most products.
If using nozzles other than the Wilger ComboJets, the Tip Wizard is still useful for identifying the flow rate and pressure of nozzle that you need. The Tip Wizard’s droplet size feature will not be usable, and instead, reference to the specific nozzle manufacturers’ spray quality data will be necessary. Choose nozzles that have a “Coarse” spray quality on average, and allow some movement into “Medium” and “Very Coarse” to suit a specific application need. Avoid “Fine” (not necessary for any pesticide, and too drift-prone) and “Extremely Coarse” (possibly insufficient coverage) unless specifically instructed by the pesticide manufacturer. Always select 110 degree nozzles, and do not use air-induced nozzles.
Advantages:
- Constant pressure (and droplet size) over a wide range of travel speeds.
- Ability to change droplet size with pressure adjustments on-the-go, without changing travel speed (depends on where you are in the duty-cycle range).
- Ability to change application volume on-the-go, without changing travel speed or pressure (again, depends on where you are in the duty cycle range).
- Instant response to shut-off, turn-on. Sprays at full pressure immediately. Does not drip.
- The new AIM Command Pro or Sharpshooter PinPoint allows for individual nozzle flow control. This enables nozzle-by-nozzle sectional control as well as turn compensation.
Considerations:
- Must keep water clean to avoid malfunctioning of tappet seal.
- Operator needs to understand system to take advantage. For example, at max travel speed (100% duty cycle), one cannot increase application volume or reduce drift by lowering pressure without first slowing down. Most flexibility is available at 70% duty cycle, and nozzles should be selected so that at average travel speed, system is near 70% duty cycle.
- Must use wider fan angle nozzles or higher boom height to get 100% overlap.
- The system’s primary purpose is to increase the consistency and accuracy of spraying by maintaining constant pressure over a wide travel speed range. It does not have a unique ability to reduce drift or water volume over a conventional system.
A conventional nozzle system can still do a very good job. However, using a conventional system with low-drift nozzles often reduces the available pressure range by raising the effective minimum pressure, usually to about 30 psi depending on the tip. Since many sprayers cannot produce pressures over 100 psi, this limits the travel speed range (max speed:min speed) to about 1.8. The Aim Command system removes this limitation by using duty cycle, not pressure, to control flow.
April 22, 2015