Category: Sanitation and Maintenance

For basics category

Remove and scrub your filters – Even when you use Dawn
This article was co-developed by Mike Cowbrough, OMAFRA Weed Management Specialist in Field Crops
Why scrub filters?
Why do we ask you to manually scrub residue from sprayer filters and housings before changing chemistries? Here are three reasons why rinsing in-place may not be good enough:
- There is potential for biologically-active levels of residue to persist in filters, even after a triple rinse, that could harm the next crop sprayed.
- Persistent residues could cause physical antagonism with the chemistry you use next. This can cost time and/or efficacy should it plug filters and nozzles or reduce spray uniformity.
- Persistent residues could cause chemical antagonism with the chemistry you use next – even several batches later. This could harm crops when the residue carried over from a much earlier application suddenly becomes soluble again thanks to detergents or pH adjusters in subsequent tank mixes.
An experiment
To some, the previous statements may seem excessive. Many sprayer operators claim that scrubbing filters is time consuming, or that they’ve never had a problem before, or that the tiny amount of residue they see in the filters after rinsing couldn’t possibly cause damage. We decided to test the efficacy of rinsing filters without removing them.
We constructed a table-top system that could circulate chemistry through a 50 mesh filter. Think of it as a scaled-down sprayer that returns solution to the tank rather than spray it out. It replicates what the line filters on a larger sprayer might experience during a typical spray day.
Table-top system to circulate spray mix at 1 gallon per minute through a 50 mesh filter.
The method
The tank (i.e. the bucket) would be filled with a tank mix and circulated through the filter to replicate a spray day. The contaminated filter could then be sampled to establish a baseline, and then alternately contaminated and rinsed in place to compare how much residue remained. Specifically, we would drop the filter housing and scrub all surfaces in 500 ml of water to collect any and all residue.
Each sample collected would be poured through a filter for a visual check of residue. A small volume would be reserved to be sprayed on soybean and white bean seedlings as a bio assay of activity.
The process
We used Sencor (metribuzin) mixed at a rate that represented the low end of the label: 250 grams of product per acre at 5 gallons per acre. Not knowing what to expect, we circulated the solution through the filter for 20 minutes pumped at a rate of 1 gallon per minute and peeked into the tank.
After 20 minutes of circulation, Sencor began to foam.
Seeing that we were creating foam, we decided to add defoamer. Then we peeked into the filter housing to see what had accumulated so far.
Very little residue was found on the filter or in the housing after 20 minutes of circulation.
Finding very little in the way of residue, we chose to let the system circulate for an hour. We felt this would represent a single real-world tank’s worth of product. Since we’d added defoamer, we decided it was safe to leave the lab and let the system circulate…
Foam overs: No fun in the field and no fun in the lab.
Despite having added defoamer, we had a mess to clean up. When we opened the bucket we noted all the product clinging to the lid (see below). We collected some of this scum to replicate what might be clinging to parts of the spray tank that are not adequately covered by rinse-down nozzles. We then dropped the filter into 500 ml of water and scrubbed the housing and filter to collect any and all residue.
Collecting residue from the bucket lid to replicate what might remain in a tank that is not sufficiently rinsed.
We then added additional defoamer and checked in regularly as we circulated the mixture for several hours to replicate a full day of spraying. This time when we checked to see how much residue we had collected, found a surprising amount.
Residue following several hours of circulation, prior to triple rinsing with water.
We replaced the filter and performed a triple rinse with water before dropping the filter to collect our residue sample. As shown below, the triple rinse cleared much of the residue, but trace amounts were still visible.
Residue following several hours of circulation and a triple rinse with water.
Dawn Detergent and the 5 Second Squeeze
We refilled the tank with Sencor and defoamer and circulated it for several hours to once again contaminate the filter. This time, however, we added detergent to the second rinse. We did this in response to claims that Dawn dish detergent removed residues from dry products such as Atrazine without having to drop the filters.
A former agrichemical rep explained that the practice likely originated in Western Canada some years ago when several growers suddenly experienced physical incompatibilities with a particular batch of dry product. It was suspected that the problem was due to abnormally cold temperatures during mixing, but the result was that many were left with solids in the tanks that could not be flushed.
Ionic surfactants are found in “cheap and nasty” shampoos, dish detergents and car care products. They can be tough on the skin, but they are of higher surfactantcy than NIS. And so, agrichemical reps bought pallets of Dawn dish detergent (Branded “Fairy” in the UK) from big box stores and found it broke the solids down sufficiently to flush the tanks. From there, it is likely growers started adding it during the rinse to facilitate cleanout. But, is the “Five second squeeze” a myth or does it work?
Results
Adding Dawn detergent to the second rinse reduced visible residue in the filter housing and on the plastic sides of pop bottles that stored the rinsate.
We saw a visible reduction in the filmy residue left behind by Sencor in the filter housing and on the walls of the pop bottles used to store the rinsate. It was easy to see why the 5 second squeeze appeared to improve matters… but was there enough residue to still there to cause trouble?
Rinsate filtered through red cloth for a visual check of residue.
We poured the rinsate from each sample through red cloth. There was little or no visible evidence of Sencor in the sample taken from the lid of the filter following an hour of spraying (left), or our baseline sample of a filter contaminated after an hour of circulation with no rinse (second from left). There was a great deal in the sample from the filter following “a day’s spraying” and a triple rinse (second from right), and less in the triple rinse containing detergent (right). These last two conditions are compared below.
Following several hours of spraying, residue following a triple rinse with water (left) and a triple rinse with detergent in the second rinse (right).
A volume of the rinsate from each sample was reserved for bio assay on soybean seedlings. The filter in the spray booth was cleaned thoroughly between conditions.
The following images show that even when there was little or no visible residue, there was still sufficient activity remaining to injure, or in the case of the triple rinse with water, kill soybean seedlings.
Summary
Bear in mind that this is a single experiment with a single chemistry, but it does support the following observations:
- Always rinse the sprayer as soon as possible and pay attention to dead-end plumbing and filters. Diligence is a function of knowing what was sprayed last, what is coming next, and the sensitivity of the crops being sprayed.
- Cleaners do not decontaminate – they loosen residues to make rinsing more effective. In our experiment, Dawn detergent appeared to reduce residue and that will keep you spraying plug-free for longer. But, the bioassay showed sufficient activity remained to cause carry-over damage.
- A triple rinse with water may be insufficient to remove residue from filters. Even if the residue left behind does not cause damage in the next crop sprayed, it can persist and has the potential to react antagonistically with subsequent sprays.
Bonus: Pro Tips
Not long after publishing this article, we were contacted by a grower who had difficulties with clay-based products plugging up his filters. It took a carry-over incident to convince him he needed to address the problem, so he installed $20 ball valves at the bottom of the filter housings. This isn’t as good as dropping and scrubbing filters, but opening and closing the valve under pressure during rinsing blew the filters clear of visible residue. Others have noted similar modifications on the pump of their tender truck to clear the filter of algae.
Other options include a hydraulic-style ball valve (stronger than plastic). Or, install a gator lock cam after the valve and insert a plug so if it’s accidentally opened it won’t dump the tank. Just keep a hose in the toolbox and insert it when you need to flush. Finally, one grower added a Thompson strainer to the sprayer and removed the screens from the Banjo Y’s. He ran a 1″ hose from the Thompson to a valve by the work station and cracks it open as part of every rinse.
A cheap and effective solution for clearing filters of residue. Not as good as dropping and scrubbing, but a great compromise.
Ball valves tend to protrude below the sprayer, so they may catch high corn. Be careful.
January 10, 2020
Biobeds for Pesticide Waste Disposal
One of the most challenging aspects of a spray operation is the disposal of leftovers or rinsate containing pesticides. Let’s be honest, too much of it is drained onto the ground in a corner of the yard or the field. Nobody’s happy about that, nobody’s proud of it, but what are the alternatives?
Waste disposal is a skeleton in the closet of the pesticide industry. One of the problems is the time-consuming nature of sprayer cleaning, and the lack of clear guidelines on product labels that pass the buck. Too often, the applicator is asked to “act in accordance with provincial or state guidelines”, which is essentially a dead end.
Figure 1: Sprayer fill station
At Sprayers101.com, we’ve tried to tackle the problem by finding ways to generate less waste (Express End Caps, Accu-Volume), by disposing of the rinsate by spraying it out, or by installing an efficient continuous rinsing system. We’d now like to talk about another component, biobeds.
What is a biobed?
Simply put, a biobed is a place where it’s safe and acceptable to dump dilute pesticide waste. First implemented in Sweden about 20 years ago, a biobed typically consists of a 1-m deep pit measuring about 3 m x 6 m or so. The pit is filled with a biomix, a mixture of cereal straw, compost or peat, and soil. The biomix, when properly prepared, acts to absorb a large amount of moisture, adsorb the pesticide molecules, and provide an environment in which microbes break down the residues.
Figure 2: Canada’s first commercial biobed installation at Indian Head, SK, 2009 (Source: Murray Belyk, Bayer CropScience (retired)).
The effluent from a properly constructed biobed system contains 90 to 99% less pesticide than what was introduced, depending on the pesticide.
Biobeds have been extensively studied and are now found throughout Europe and many parts of Central and South America. Canada currently has 6 research biobed sites in the West, and a further 17 in Quebec. The systems have been researched by Agriculture & Agri-Food Canada (AAFC) in recent years, with promising results.
Figure 3: European biobed installations, 2016 (Source: Jens Husby, Biobeds.org).
Figure 4: Global biobed installations, 2016 (Source: Jens Husby, Biobeds.org).
Constructing a biobed
There are many possible variations of biobeds, some relatively simple and others engineered to address certain specific needs. A great deal of creativity can be used to customize a biobed for any operation.
A simple biobed
The following is a variation of the simplest biobeds, and these are the types first tested by AAFC in Saskatoon and Indian Head, Saskatchewan about 10 years ago. This design is based on the biobeds established in Sweden and the UK, and is a good way to learn about the system.
Note that this biobed has an impermeable liner, so it’s a closed system. Excess water that leaches to the bottom must be removed and cycled back to the top of the biobed.
- Create the biomix by blending two parts, by volume, chopped cereal straw or wood chips (not cedar), one part mature plant-sourced compost or peat and one part relatively coarse-textured soil (for optimal drainage). Add water as necessary as if making compost. Allow to sit for four to six weeks.
Figure 5: Biomix preparation.
- During this waiting time, the biomix will warm and form a white-mold complex. This is the microbial basis for its ability to break down pesticide residues. White mold will be visible on the cellulose portions of the biomix.
Figure 6: white mold (Source: AAFC).
- Identify a well-drained site easily accessible by spray equipment. Avoid low spots as water management becomes problematic.
Figure 7: Site selection and/or biobed covering are essential to avoid waterlogging (Source: Murray Belyk, Bayer CropScience (retired)).
- Dig a pit sized to suit your requirements. As a rule of thumb, 1 m³ can process about 1000 L of liquid in a season. Rainfall is included in this amount.
Figure 8: A nice looking pit.
- Line the pit with a geomembrane liner. 40 mil is plenty thick; any thicker and it gets hard to handle. Include a raised berm at the edge.
Figure 9: Liner creates a closed system that will require a way to remove leached water.
- Install weeping tile at bottom of pit, and extend it to ground level. This will be useful to determine water status and remove water if necessary.
Figure 10: Weeping tile to collect excess water.
- Cover weeping tile with pea gravel and a silt trap. This serves to make leached water freely available for removal.
Figure 11: Pea gravel over weeping tile.
- Fill pit with biomix, anticipating significant settling. Top up as necessary over next few weeks. Use extra biomix to create a slope away from berm.
Figure 12: Filled biobed.
- Establish a bromegrass cover by transplanting or sodding. This is an important way to remove excess water via evapotranspiration.
Figure 13: Early sod growth on biobed at Indian Head, SK.
- Introduce pesticide waste to biobed, managing moisture content to avoid waterlogging.
Figure 14: Pesticide waste entering biobed via drip irrigation.
Introduction of pesticide waste to the biobed
Moving pesticide waste from the sprayer to the biobed should be easy and trouble free. A simple pad built beside biobeds, either sealed with concrete or asphalt, or with a hardy geomembrane liner, works well. The sprayer is cleaned on this pad and rinsate flows into a drain. A sump pump lifts the rinsate to a storage tank from which it is introduced via gravity or pumped drip irrigation.
Figure 15: Biobed system in Simpson, SK. Rinsate from sprayer is collected in a sump, which is pumped to the black storage tank in background. Rinsate is introduced into biobed (blue tub) as needed (Brian Caldwell in foreground, left, Larry Braul, right).
When not in use, the sump drains freely to dispose of rain water.
Others choose to pump or dump rinsate directly into a holding tank, from where it can be pumped onto the biobed.
Figure 16: Holding tank at biobed in Outlook, SK.
Some European systems include driving supports on the biobed so the sprayer can be parked directly over top.
Figure 17: Steel beams can allow (light) sprayer access (Source: Eskil Nilsson via Biobeds.org).
A two-stage biobed
The same basic building principles apply as in the original simple biobed. However, instead of reintroducing the effluent to the top of the biomix as it collects on the bottom, it is instead pumped onto a second biobed. This biobed then degrades any remaining product. This system is more efficient at degrading persistent products, and allows for better water management.
Figure 18: Two-stage biobed system at Outlook, SK.
The principle has proven effective, helping degrade more difficult pesticides to acceptable levels.
Above-ground biobeds
One of the problems with below-ground biobeds in wet climates is the difficulty managing water. Above-ground biobeds can address this issue by eliminating the possibility of surface runoff being added to the biomix. Adding a rain cover would also be easier and more effective.
Above-ground biobeds can be edged with plywood, or placed entirely into plastic tanks whose tops have been removed.
Figure 19: Above ground biobed installation with plastic tub.
One potential problem with above-ground biobeds is the later spring warming of this installation compared to below-ground types. Cold temperature reduces the effectiveness of biobeds due to the reliance on microbial activity. Heat tape has been tested by AAFC and shown to be very effective at warming the biomix and stimulating initial microbial activity. Passive solar systems have also been studied but are more difficult to install.
Figure 20: Heat tape (Source: AAFC).
Figure 21: Passive solar biomix heating system.
Phytobac and Biofilters
European designs have utilized plastic containers to form of various designs, including the commercial “Phytobac” systems from France and developed with the support of Bayer CropScience.
Sequential biofilters have also been implemented. The leachate simply migrates through the biomix into the next container below. Eventually, adjacent biofilters containing plants act to remove the moisture.
Figure 22: Phytobac installation, cross-section.
Figure 23: Biofilter installation in Belgium (Source: Inge Mestdagh via Biobeds.org).
Biomix longevity
Swedish and UK research has suggested that biobeds require minimal maintenance aside from water management in closed systems. Biomix will settle over time and may need to be topped up. After five to eight years of use, it has been recommended to remove biomix and distribute it over a field with a manure spreader.
Canadian research results
Extensive analysis of pesticide degradation in five biobeds across Western Canada was conducted as part of a three-year study led by AAFC. Between eight and 51 products were analyzed per site, including herbicides, fungicides, and insecticides. Their results showed that single biobeds could remove about 90% of the introduced pesticide, and two in sequence usually removed more than 98%.
Pesticides that tended not to degrade rapidly were removed to a greater degree in the second biobed.
In the AAFC studies, three herbicides were more difficult to remove in the tested biobeds: clopyralid (e.g., Lontrel, Stinger), bentazon (Basagran, Storm) and imazethapyr (Pursuit, Arsenal). For these three, roughly 60% was removed in a two-biobed system.
Concentrated pesticides should not be introduced to a biobed as this will kill the microbial populations.
Some fungicides were shown to depress microbial populations but only temporarily. Microbial breakdown still occurred.
Biobed manual
AAFC has authored a comprehensive manual on biobed operation and installation based on research experience in Canada and elsewhere. It will be available here in late June 2018.
The future of biobeds
Research into biobeds remains active around the world. Different substrates for the biomix are being studied to suit local availabilities. Various systems, ranging from simple to highly engineered are being studied. Degradation effectiveness for various influents remains a topic of significant interest. Producer adoption and implementation are being reported.
Thanks to funded research projects, biobeds are up and working at Canadian institutional sites such as government research centres, and there are opportunities for county and municipal government sites. For biobeds to be a viable option on North American farms, their design needs to remain simple and their integration into established practices needs to be seamless. Producer experience and feedback are essential
Learn more
Valuable information on biobeds can be obtained from these two websites:
Voluntary Initiative (UK industry)
Biobeds.org (International research)
Note: Brian Caldwell and I first learned about biobeds from Eskil Nilsson (website) during a visit to Sweden in 2001, and obtained support for initial studies in Saskatoon and Indian Head from the Pest Management Centre as well as Bayer CropScience. Brian took a lead in our creative and technical efforts over many years. Dean Ngombe, under the co-supervision of Diane Knight at the U of S and myself, produced the first M.Sc. thesis, and with significant input from Allan Cessna, the first scientific publications in Canada on biobeds. Thanks for Larry Braul and many collaborators for leading the most recent AAFC study and generously sharing resources, and Erl Svendsen, Bruce Gossen, and Claudia Sheedy for editorial input.
May 20, 2018
Hydraulic Fittings: A Galling Metallurgical State of Affairs
So it’s been a long spraying season and as you perform your annual maintenance you grudgingly admit that the hoses have given their all. Before you run out to get more of the same, give some thought to the hydraulic fittings (i.e. hose adaptors and couplers). Many feel that stainless steel (SS) is the best choice for hydraulic fittings: It must be, because it’s certainly the shiniest and most expensive choice! But before you opt for stainless, here are a few things you should know.
SS requires surface oxidization to resist corrosion. Oxidation forms a protective barrier called a “passivation layer”, but it’s susceptible to mechanical damage. It can be penetrated as abrasive powders flow past. The layer will reform when it dries, only to be sanded off again during the next spray. The wear is on-going. If the newly-exposed SS remains submerged in a liquid, the passivation layer will not reform. Without it, SS surfaces corrode at a high rate, and in extreme cases SS will even corrode inside of itself and become a hollow shell.
When two pieces of stainless steel are forced together, the passivation layer gets scraped off, allowing parts to gall (or ‘weld’). In fact, any similar metals in physical contact will naturally gall to each other, but stainless steel is especially susceptible. When disassembled, the ‘welded’ material must be torn apart. This destructive galling can be reduced with lubrication during assembly and avoided altogether by mating dissimilar materials (e.g. bronze and stainless steel). Technically, mating different types of stainless steels (e.g. martensitic against austenitic) could work, but it is possible that two different alloys electrically connected in a humid environment may act as a voltaic pile and corrode even faster. This is probably a moot point because many do not have access to different SS alloys when choosing fittings.
Sometimes we see black or galvanized pipe fittings on sprayers, but I don’t recommend either. Galvanizing is only slightly better than black pipe and since the threads are cut after being galvanized the threads are essentially black pipe, anyway.
So what about plated steel fittings? They’re available with swivels and can seal on faces and seats (rather than on the thread – which is much easier to assemble and disassemble). They can be crimped onto the hoses, eliminating the need for hose clamps that fail or snag and cut the operator. (As a related aside, hydraulic hose is not really compatible with most spray products – the steel wire inside the rubber begins to corrode and unexpected failure is common. Even when spraying above 200 psi there are better high pressure-rated choices than hydraulic hose.) Mechanically, these fittings are a great option, but unfortunately the plating is designed for oil, not pesticide. Within a year they rust internally and seize up. To add insult to injury, the flaking rust is notorious for plugging nozzles.
A better choice is brass (or even bronze) fittings (e.g. pipe, SAE 45° and hose barb). Just like the crimped plated steel fittings, brass SAE 45° fittings can swivel and seal on seats and they are easily assembled and disassembled over many seasons. Brass fittings are more costly than black or galvanized pipe but cost less than hydraulic or SS fittings. Conveniently, they’re available at most hardware stores.
While brass may be the best metal material for the sprayer fittings, I feel that plastic is the most economical and in many applications is superior to metal. But, that’s a topic for a follow-up article. So, before you spring for SS hydraulic fittings, consider cheaper and more effective alternatives like brass or plastic. And, if only for the sake of your mechanic, please don’t over tighten fittings. It is unnecessary and causes endless damage and frustration.
October 28, 2015
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
Cleaning Your Sprayer
We all know the importance of cleaning out a sprayer. It protects a sensitive crop. It protects people working with the sprayer. It protects the sprayer and its components. But cleaning the sprayer is a pain. Here are some tips to make it easier.
Some herbicide label instructions are cumbersome, requiring many flushes with full tanks of water. Many applicators look for shortcuts and hope they get away with it. It doesn’t have to be guesswork. The following is a checklist that may help.
Be Prepared
A few supplies can help ensure a clean sprayer tank.
- A defoaming agent saves water and time
- A cleaning agent (commercial products, or simple household ammonia) is useful, and recommended, for Group 2 products except the imidazolinones.
- A supply of clean water, preferably with its own pump, and a pressurized spray hose helps clean the sprayer inside and out.
- A wash-down nozzle (whose flow requirements can be met by the clean water pump) can automate the tank wash-down.
- A bucket and brush for rinsing screens is very useful.
Products to Watch:
The products most frequently implicated in sprayer contamination are two members of the Group 2 modes of action: the sulfonyl ureas (e.g., thifensulfuron (Refine) and tribenuron (Express)), and the triazolopyrimidines (e.g., florasulam (Frontline, PrePass) and pyroxsulam (Simplicity)). Since these herbicides dissolve better at higher pH, proper cleanout usually requires ammonia, a weak base that raises the solution pH. The third member of Group 2 products, the imidazolinones (imazethapyr (Pursuit), imazamox (Solo, Odyssey), imazamethabenz (Assert), imazamox (Ares, Adrenalin, Altitude or Viper)), tend not be implicated in as many residue issues, and don’t require ammonia for cleanout.
Be Prompt and Thorough
Remove pesticide from mixing and spray equipment immediately after spraying – it makes the job easier. The main areas of concern are the tank wall, sump, plumbing (including boom ends), and filters. First, spray the tank completely empty while still in the field. It’s sometimes OK to cover previously sprayed areas – all herbicides must be crop-safe at twice the label rate to be registered by the PMRA. Take care with residual products that may create problems down the road. Reduce the rate or choose a fallow field to be certain. Second, add 10 x the sump’s remnant of clean water, circulate, ensuring agitation is on, and spray it out in the field as well. Repeat. These two rinsing steps will take care of the majority of the cleaning and won’t take very long. The less remaining volume there is in your tank after the pump draws air, the less water is needed to dilute this remainder to an acceptable concentration. Having a clean water tank on the sprayer and a wash-down nozzle makes this job easier.
Visual Inspection
Herbicide residue may precipitate out of solution in some parts of the sprayer or plumbing. A thorough visual inspection can identify these problem areas and ensure that they are cleaned properly.
Tank Wall
Removal of residues from tank walls is best accomplished with a direct, pressurized spray. Make sure all parts of the wall have been in contact with clean water. Use a wash-down nozzle if it provides complete and vigorous coverage of the interior tank surface.
Sump
Empty the sump as completely as possible by spraying it out. Any spray liquid or herbicide concentrate remaining in the sump area will be re-circulated in the sprayer. The only way to remove any remaining herbicide is through dilution by repeatedly adding water, and leaving as small a remainder as possible.
Plumbing and Boom
Plumbing can be a significant reservoir of herbicide residue. Removal from plumbing can be achieved by pumping clean water through the boom while ensuring that all return and agitation lines also receive clean water and all residue is flushed out. This may require opening and closing various valves several times, and repeating the process with new batches of clean water. Boom ends can extend up to 6” beyond the last nozzle at each end of each boom section. These ends must be flushed to removed trapped residue. A useful product that does this automatically is the Pentair Hypro Express Nozzle Body End Cap, or better yet, consider recirculating booms.
Dilution
The most effective use of a volume of rinse water is to divide it equally across several repeat washes. Assuming a 10 gallon sump remainder, three washes with 30 gal each are as effective as two washes with 70 gallons each, and equal a single 600 gal wash.
It’s even more efficient to use a separate clean water pump, introducing clean water as the rinsate is sprayed out. This saves water and time, and results in even more dilution.
Filters
Nozzle screens and in-line filters can be a significant reservoir for undiluted or undissolved herbicide and are one of the most overlooked parts of sprayer decontamination. Remove all filters and nozzle screens and thoroughly clean these with fresh water. Run clean water through plumbing leading to the screens.
Nozzle Bodies
Nozzle bodies can harbour herbicide mixture. When cleaning a spray boom, rotate through all nozzles in a multiple body to ensure clean water reaches all parts of these assemblies. Remove screens that may have been used with herbicide.
Tank Cleaning Adjuvants
Adjuvants such as ammonia can assist the tank decontamination process, especially with sulfonyl urea and triazolopyrimidine-containing products. Ammonia does not neutralize herbicides, but it does raise the pH of the cleaning solution which helps sulfonyl urea herbicides dissolve. When decontaminating after an oily (EC) formulation, the use of a wetting agent such as AgSurf will assist in removing oily residue that may trap SU herbicide on tank and hose material. Commercial tank cleaning products that contain ingredients for removing persistent deposits are available.
Tank and Boom Material
Both plastic and stainless steel are common tank and wet boom materials, and both can be cleaned using the above procedures. However, stainless steel is easier to clean, and this means that less time may be required. Consider the choice of materials a productivity factor in your next purchase or upgrade decision.
Rinsate Disposal
Always spray out the tank in the field. Do not drain the tank while stationary unless you are certain it is free of pesticide and that you are away from sensitive areas and waterways. Consider a continuous rinse system. Consider building a biobed for safe disposal of dilute pesticide waste.
Sprayer cleanout will probably never be the easiest job on the farm. But looking at it in a smarter way can prevent frustration and save time.
April 21, 2015