Tag: continuous

Installing a Continuous Rinse System
Cleaning, flushing, triple-rinsing… whatever you call it, sprayer sanitation is a time-consuming and distasteful task.
Methods vary, but they generally span from the classic triple rinse (30-45 minutes) to a full tear-down and decontamination (many hours and likely an overnight soak). The operator decides how much time and effort to invest depending on the chemistry they’ve just used and the crop they intend to spray next. Learn more about the power of dilution in this article and in this article.
Unfortunately, two facts are certain:
1. At minimum, operators should rinse the sprayer at the end of each day… and they generally don’t.
2. It is only after spraying a sensitive crop that the operator truly knows whether the sprayer was cleaned sufficiently.
Continuous Rinsing
We’ve promoted Continuous Rinsing as a viable alternative to Triple Rinsing in previous articles (see here and here). Executed correctly, the method:
- greatly reduces the time required,
- is as effective,
- eliminates operator exposure, and
- reduces potential environmental contamination.
Continuous rinsing requires the installation of a dedicated “rinse pump” to transfer clean water to the product tank from the rinse tank via the wash-down nozzles. This permits the main product pump to operate simultaneously, emptying the product tank and spraying the rinsate out the boom.
Imagine your sprayer empties at the end of the row. You position the sprayer at a headland or a row you sprayed earlier. A toggle switch in the cab engages the rinse pump and the wash-down nozzles start spraying clean water into the product tank. You then resume driving and spray until the rinse tank is empty. During the process, any solution in the return/bypass line is quickly diluted, and any standing volume in the system is displaced by clean water.
It takes five minutes and you never left the cab.
Remember: Rinsing can dilute residue to ~2-5% in most of the sprayer plumbing, but it is not intended to replace the more rigorous decontamination process. Closed circuits, filters and dead-end plumbing can still harbour residue >15%.
Installation
Working with GreenLea Ag Center in 2017, we installed a Continuous Rinse system on a Case IH Patriot 4440. It has a 1,200 gal. product tank, a 140 gal. rinse tank and a 120 foot boom. A parts/price list for the Patriot installation appears at the end of this article.
Additionally, we have included the parts/price list from our 2016 HJV Equipment installation on a RoGator 700, which had a 700 gal. product tank, 50 gal. rinse tank and a 90 foot boom.
Still further, we have included three homegrown solutions from operators that developed their own continuous rinse systems.
Sizing the Rinse Pump
It is very important that the rinse pump has the capacity to operate the wash-down nozzles and still supply clean water at a rate approximately equal to the rate at the boom. Basically, “in must equal out”. If the rinse pump supplies too much clean water, the volume rises in the product tank and efficiency is reduced. If it cannot supply enough, the main product pump will lose suction and not function correctly.
We installed a Hypro 9303C-HM1C centrifugal pump (max flow rate of 114 gpm at 130 psi), matching the make and model of the exiting product pump. A length of channel was installed on the chassis to mount the pump and close-coupled hydraulic rinse pump motor, and a valve block.
Really, electric pump installation is easiest. An alternate pump that has been used is this one from Pattison Liquid. For added benefit, it’s a chem transfer pump that can handle the pesticide formulations. If the pump doesn’t give enough flow, a second one can be installed parallel to double the flow.
Hydraulics
Let’s being with advising caution: If you are uncertain about your hydraulic capacity (and tightly designed systems rarely have extra) then consult with a manufacturer-certified service technician, or consider an electrical alternative.
For the Patriot, the auxiliary hydraulic circuit was used to drive the hydraulic rinse pump; we piggy-backed off of that existing system. In this case, Continuous Rinsing increased the load on the auxiliary hydraulic circuit, but only marginally, so performance was acceptable.
We drew that hydraulic flow directly from the auxiliary pump output using a ‘T’ piece to ensure full pressure was available when needed. Then we broke into a common low pressure return manifold using another ‘T’ piece to provide the return flow.
Originally, we were concerned that robbing too much hydraulic flow could compromise sprayer operations. We therefore exchanged the hydraulic motor that came with the pump for one that required less hydraulic flow. However, the pump operated at such a high speed that the rinse tank was drained in two minutes! We felt this would not give the operator enough time to make minor adjustments (see the “Avoid Airlock” section later in the article). We also felt the rinsate would not have enough time to hyrdate any residue in the tank and lines. We therefore returned to the motor that came with the pump, slowing the pump and bringing our rinse time to approximately five minutes.
We installed an on/off hydraulic control valve block and solenoid controlled by a toggle switch in the cab. When the rinse switch was engaged, 12 volt DC opened the solenoid, allowing hydraulic oil from the auxiliary pump to turn the rinse motor, which in turn powered the rinse product pump.
Avoid Airlock by Balancing Flow
While Continuous Rinsing works well with an unbroken stream of clean water, there is demonstrated benefit to allowing the pump to draw a small amount of air. The bubbles are reputed to scrub the lines more effectively than water alone. It is possible that the new Hypro 9307 series centrifugal pump, which claims to eliminate dry run, would facilitate this.
However, avoid excessive cavitation or airlock of the main product pump. This will damage the pump seals and interfere with pump suction. If the main product pump is a piston-diaphragm pump, avoid losing the prime by letting a small volume of rinse water build up in the product tank before spraying the rinsate.
Maintaining the balance between the supply from the rinse pump, and demand by the product pump, will take careful trial and error. If the sprayer employs a rate controller, speeding up or slowing down travel speed is a means for making adjustments to match the two flows. Alternately, an operator can adjust the pressure regulator manually. Remember, the nozzles won’t need to work optimally so you have the option to use fairly low pressures to match flows.
In the case of an operator applying 28-0-0 using dribble bars or fertilizer nozzles, there is likely too much flow at the boom for the rinse pump to keep up. While we have not tried it, but as long as there was sufficient volume in the clean water tank, it might be possible to rinse the boom section by section, starting with the outside sections and moving in towards the centre.
Lessons Learned
The installation was a learning process, during which we noted the following:
- At first, the rinse tank slowly emptied through the rinse pump, even when it wasn’t in use. We prevented this by installing a 10 psi check valve between the pump and main tank.
- The rinse pump ran dry and burned the seals when the operator forgot to turn it off after the rinse tank was empty. We considered a timer or alarms to prevent this, but chose to install a level sensor (essentially a float) which would cut the 12 Volt DC feed to the on /off solenoid, effectively turning the system off when the rinse tank was empty. Note: the sensor is not in the parts list – it was purchased for ~$10.00 CAD from Amazon.
- When deciding where to draw hydraulic flow to run the rinse pump, we first tied into the main hydraulic circuit (i.e. not the auxiliary). This negatively affected both steering and boom control. Beware drawing flow from critical safety systems such as steering.
Future Development and Other Advantages
GreenLea was exploring an option to use the rinse pump to bypass the product tank, and flow directly to the boom. This can be accomplished by teeing an electrical 3-way ball valve just after the pump to allow flow directly from the rinse tank (see dashed line in the flow schematic shown earlier in the article). Imagine being rained out, or having excess mix left in the tank at the end of the day. This system would allow the dilution of any corrosive chemical from a sensitive precision application system without losing or contaminating the spray tank. It should be noted, however, that high precision spray systems (e.g. AIM Command, Pro and Flex) would still require the operator to open the boom flush valves manually to allow the boom purge.
Growers have suggested the system might also be used to get a sprayer to end of a row if it threatens to run empty before completing the pass. A small volume of clean water added to the tank would displace the 15-30 gallons of unusable volume and stretch the application. Be aware that this would also dilute the product due to the agitation/bypass and should only be considered when a minute or less of additional spray is required.
Homegrown Solutions
Tyler Patriot (Electrical)
David Kucher (@DavidKucher) from Saskatchewan installed Continuous Rinse on his Tyler Patriot (75 foot boom, 800 gal. product tank).
Here’s what he had to say:
The rinse system I was using on my sprayer previously involved a lot of time and effort. Plus, the quality of job it did was sometimes imperfect (I keep pictures on my phone of a canola crop that was damaged because of a poor rinse job from a few years ago). The old system used the main product pump to rinse, so there was a bunch of valves under the sprayer that needed to be turned, and the pump had to reprime for each rinse. It was tedious.
Uncertain about the hydraulics, David elected to use an electrical pump, but had difficulty finding one that would produce enough pressure and flow. Most electric pumps were too small and it would have taken more than one, plumbed in parallel, to achieve the volume numbers required. However, David found a high-flow 489G-95 AMT High Head Washdown Pump (1 HP, 1-1/4×1 IN/OUT, 12 VDC,Cast Iron,Buna-N) which he got from the US for about $1,200.00 CAD. Max flow was 56 gpm.
Note: In 2020 this pump model changed to the 12DC-95.
He removed the majority of plumbing, valves, and related complexity from the old rinse system. The Continuous Rinse was comparably simpler and isolated from the rest of the sprayer plumbing. It just involved a fill line from his two clean water tanks, the new rinse pump, and the existing rinse nozzle inside the product tank.
When the product tank empties, David holds down a push button dead-man switch he installed to activate the rinse pump. If he wants to do a more thorough job, he flushes the product tank and plumbing for about two minutes, then stops, gets out and opens the boom end valves. Then he climbs back in and does another one minute flush.
Approximately 30 gallons of water go through on each flush and my only issue is that I waited so long to install the system.
Author’s note: Positive displacement electrical pumps (which have zero risk of seal loss) are reasonable alternatives to centrifugal pumps. Depending on the size of the sprayer, multiple pumps plumbed in parallel can provide sufficient flow. We elected to use two Hypro electric roller pumps (model 4101 N-H) for the 2016 RoGator 700 installation. Cheaper, low amperage 12V diaphragm pumps from Delevan and FLOJET with capacities of 5-8 gpm are also available.
John Deere 4830 (Hydraulic)
Russ Enns (@EnnsFarms) from Saskatchewan installed a Delavan HD Magnum 125 hydraulic driven pump (1-1/4” suction, 1” discharge, 5-7 gpm of hydraulic flow). He mounted it on the same mounting plate as the main product pump, just on the opposite side, using the same bolt holes.
It was tied hydraulically to the main product pump, so the rinse pump could only run when the product pump was operating. The hydraulic supply from the sprayer went through an electric/hydraulic block via a solenoid resting in the closed position. A rocker switch in the cab used 12V to activate the rinse pump from the cab. Return hydraulic pressure from the rinse pump was tee’d into the main solution pump hydraulic return.
The clean water intake for the rinse pump was tee’d into the factory rinse tank. The discharge side of the rinse pump was plumbed to a check valve and tee’d into factory tank rinse system. Here’s the discharge line, check valve and tee into factory rinse (below).
Russ mounted a large pressure gauge on front right axle to monitor rinse pressure. It’s easy to see from the cab, and easy to tell from the pressure when the rinse tank is empty.
In this case, Continuous Rinse is used in tandem with an Accu-volume tank gauge so Russ could monitor the level in the main product tank from the cab. Depending on the nozzles being used, he found that the rinse pump supplied clean water faster than the rinsate could be sprayed.
So, after finishing a field (or changing chemical, etc.) Russ turned on the rinse system while spraying the rinsate out on the field. The Accu-volume alerted him if clean water was accumulating in the product tank. If it got to ~20 gallons, he would briefly suspend the rinse pump while spraying to allow the level to drop. Then, he would start the rinse pump back up. He repeated this process until the clean water tank was empty.
Russ had many of the main components on hand, but estimates replacement value at ~$1,200.00 CAD. He noted that while installation was straight-forward, he originally piggy-backed the rinse pump’s hydraulic supply off the main solution pump, and it didn’t work correctly. We did that too, Russ 🙁
“Time savings and environmental considerations are the biggest benefit of this system to me. Being able to finish spraying a field, and immediately start rinsing and spraying the diluted solution is a huge time saver. I feel it’s a far more thorough rinse and a better/quicker dilution rate compared to how I previously handled rinsing and spraying out the diluted solution. Another benefit is that even though it’s plumbed into the factory rinse, the factory rinse system can still be used normally if for some reason the continuous rinse pump quits.”
Gregson Trailed (Electrical)
Continuous Rinse isn’t only for grains and beans. Matthew Droogendyk installed two 12v pumps on his trailed vegetable sprayer that matched the flow of the main pump. They had an electrician install a box for switching the the pumps and two solenoid valves on at the same time.

They noted an issue when trying to prime the main pump after emptying the tank. If the tank was sprayed completely empty, the main pump took time to get primed again. This affected rinsing time as well as the balance between supply and demand. Through trial and error they determined that running the rinse pumps for 1 minute (~15 gal) gave enough time to rid the main pump of air. Then the flows matched at about 15 gpa. Re-priming took about 5 minutes, and then an additional 2 or 3 to rinse using about 45 gallons of clean water. They found there was no need to replace their original tank rinse nozzles.
Tank Rinse Nozzles
One of the challenges of installing continuous rinse is ensuring the tank rinse nozzles are capable of rinsing the entire solution tank interior at potentially low pressure and low flow. In 2019, Lechler released the ContiCleaner range of rinse nozzle. Four ISO colour-coded nozzles capable of operating from 2-5 bar (29-72.5 psi), with flows from 6.5-32.3 L/min. (1.7-8.5 gpm). This will enable operators to better match the rinse nozzle(s) to the clean water pump. Be aware they are very difficult to source in North America. We tried and weren’t able to get them.
Parts / Price List
The following two parts/price lists are in Canadian Dollars. They do not include tax or labour and prices change depending on where and when parts are purchased. As you have read from the operators that installed their own Continuous Rinse systems, there are many possible solutions, so these lists are provided only for reference. Click the link to download a PDF.
- Parts/Costs List – Patriot 4440
- Parts/Costs List – RoGator 700
Learn More
So far we’re aware of two Ontario companies and one Belgian company with experience installing the system. We will expand this list over time.
Before contacting them, have the following information on hand:
- Sprayer tank volume (both product and rinse, if applicable)
- Boom length
- Nozzle spacing
- Largest nozzles mounted/used on the sprayer (excluding fertilizer nozzles)
- Power available on sprayer (e.g. 12V available? Max amp? Hydraulic capacity?)
Thanks to Russ Enns, David Kucher and Matthew Droogendyk for sharing their install stories. Thanks to Adam Beaumont and Ehrin Frid for the Case IH and RoGator installations, and to Mike Cowbrough (@cowbrough) of OMAFRA and the Ontario Soil and Crop Improvement Association for collaborative support.
May 19, 2022
Continuous rinsing for airblast sprayers
Why Rinse?
Airblast sprayers are not rinsed as frequently or as diligently as field sprayers. This is primarily because they are not used to spray herbicides, so residue carry-over doesn’t incur an immediately obvious penalty. The typical operator rinses prior to long-term storage or when cross contamination might cause some form of antagonism (e.g. dormant oil followed by Captan or sulfur).
Learn more about the difference between rinsing and cleaning in this article.
Aftermarket Rinsing Systems
Airblast sprayers can be outfitted with rinsing systems that permit operators to rinse quickly, easily, and dispose of dilute rinsate in rotating locations.
A Serial Rinse (SR) system, common on field sprayers, re-purposes the pump to transfer clean water from a saddle tank to the product tank via tank rinse nozzles. The operator introduces a volume of clean water to the remaining volume in the tank, circulates it through the system, and then sprays the rinsate in the crop. Repeating this process three times (i.e. the Triple Rinse) serially dilutes the remainder, resulting in a higher dilution factor than a single high-volume rinse.
A Continuous Rinse (CR) system requires the addition of a dedicated rinse pump. In this case the operator introduces clean water to the tank via tank rinse nozzles while simultaneously spraying. While there is circulation from the bypass (and/or agitation) circuit, the remaining volume is diluted and essentially displaced by clean water.
Objective
Using a fluorescent dye tracer as an analog for pesticide, we wanted to explore the effectiveness and efficiency of both systems. We describe the fluorimetry method in this article. We installed a CR system in a 2,000 L H.S.S. tower sprayer, which unlike most North American airblast sprayers, already features a SR system (150 L clean water tank and two tank rinse nozzles).
Installing a Continuous Rinse System
Installing a CR option required us to address the same three criteria we have already discussed in previous articles on field sprayer installs:
- Identifying a CR pump with sufficient flow to operate the tank rinse nozzles
- Satisfying the electrical or hydraulic requirements of the CR pump
- Matching the supply flow from the CR pump to the demand flow at the booms
The Hol sprayer with an 18-nozzle ducted tower, 150 L clean water tank and two tank rinse nozzles. Inset: Rhodamine WT dye used as a pesticide analog for comparing residue levels.
We mounted two electric Shurflo pumps in parallel to provide flow sufficient to match the typical demand at the booms without excessive electrical load.
Parallel electric Shurflo pumps drew low amperage and provided sufficient flow to the boom.
We found that while the CR flow spun the tank rinse nozzles weakly, the spray didn’t reach all interior surfaces. This was remedied by adding a deflector plate to the bottom of the nozzles to redirect flow.
A brass disc mounted on the tank rinse nozzle deflected spray to all interior surfaces.
We encountered a complication installing CR on an airblast sprayer compared to a field sprayer. Most field sprayers have rate controllers that permit the operator to adjust travel speed or ‘dial in’ a rate to match boom demand to CR pump supply. Unless the airblast sprayer already has this feature, the operator has to calculate in advance how best to match the flows.
The calculation has to be performed for each unique output (e.g. dilute or concentrate nozzle arrangements). The flow from the CR pump is a known constant. The nozzle output is variable according to operating pressure, calculated using a nozzle guide. The operator can adjust pressure (bypass or pressure regulator), PTO-speed (on positive displacement pumps), or even alternate between booms or boom-sections to match the flows.
Matching flow demand to supply using a nozzle catalogue.
In our case, the operator was using 12 blue Albuz hollow cones in their orchard. We knew the CR pump output was 24.25 L/min. So, by setting the pressure to 6.1 bar prior to rinsing, we were spraying about 24.5 L/min. We parked the sprayer and watched to ensure the sump did not fill or drain during CR. Note in the following video how well the two flow rates were balanced (the camera was accidentally turned when we showed the vertical boom).
During trials we noticed that as the sprayer climbed uphill the water level in the tank shifted and the pump drew a little air, causing the nozzles to briefly sputter. This was a welcome sight given reports that introducing a few air bubbles during continuous rinsing can be beneficial.
Field Testing
During testing, we filled the 2,000 L Hol sprayer with 500 L of water and a final concentration of 0.25 ppm rhodamine (0.5 mL dye per 500 L water). The clean water tank was filled to 150 L. We allowed the mix to circulate for two minutes before priming the booms by spraying for a minute. A 50 mL sample was then drawn from the manifold (see below) and later used to represent the starting concentration during the analysis. The sprayer then drove through the orchard, spraying until empty.
Samples were drawn after the tank, before the manifold. Note the telltale Mancozeb coating the sprayer. PPE was worn.
Serial Rinse testing: When the sprayer was empty, the operator left the cab to introduce 75 L of clean water to the main tank via the tank wash nozzles. The rinsate was circulated for one minute before the operator returned to the cab and sprayed the orchard until empty. A 50 mL sample was drawn from the manifold to represent the concentration half-way through the rinse. The process was repeated for the remaining 75 L of clean water and a second 50 ml sample was drawn to represent the final concentration. We did this twice. It took about 12 minutes to rinse the sprayer and the operator had to leave the tractor cab twice.
Continuous Rinse testing: When the sprayer was empty, the operator stopped spraying and engaged the continuous rinse pump. After a few seconds, he continued driving and spraying rinsate. When 75 L had passed through the system, we paused to draw a 50 mL sample from the manifold to represent the concentration half-way through the rinse. The operator continued until the remaining 75 L was sprayed and a second 50 ml sample was drawn to represent the final concentration. We did this twice. It took about 5 minutes, 45 seconds to rinse the sprayer and the operator did not leave the tractor cab.
Sample Analysis: A Turner TD 700 fluorometer was calibrated using samples from the tank. Samples were diluted when necessary to ensure they fell in range of the calibration curve (where there is a linear relationship between the concentration of Rhodamine WT and Raw Fluorescence Units (FSU)). This range spanned a maximum of 0.1 ppm and a detection limit of 0.01 ppm active ingredient. Having previously tested recovery accuracy of 95%, data was adjusted accordingly.
Results of rinsate analysis. n=2.
Observations
While both methods diluted the residue significantly, the remainder following both Serial and Continuous Rinse was much higher than anticipated. This may be an artifact given that both concentrations are potentially below our detection limit, per the following:
Assuming 10 L of residual spray volume left in the system once “empty”, 75 L added would give a dilution factor of 9 (according to the ). While the first 75 L of Continuous Rinse seems to remove more residue than a single addition of 75 L, both are higher than anticipated. A subsequent addition of 75 L should result in a dilution factor of 72. In this case, the remainder would be below our fluorometer’s detection limit, and could explain the results.
Nevertheless, there were positive observations:
- Continuous Rinse resulted in a more dilute rinsate with less water than Serial Rinse.
- Continuous Rinse took less time than Serial Rinse.
- The operator did not leave the tractor cab during Continuous Rinse.
- Potentially, any remaining water from the Continuous Rinse system could be used to operate a spray wand to rinse the sprayer exterior before leaving the crop.
- Both systems encourage improved airblast sprayer sanitation and reduce environmental impact from point source contamination.
Thanks to ProvideAgro for performing the installation, Wilmot Orchards in Ontario for supplying the sprayer and running the trials, and OMAFRA summer student Aidan Morgan for assistance with the data analysis.
June 4, 2019
How Clean is Clean?
One of the more perplexing questions in tank cleanout is knowing when the cleaning process is good enough to prevent harm. This question is especially relevant to producers that grow canola and use Group 2 herbicide products, or grow soybeans and use dicamba on some of their area. In both of these examples, crops can be extremely sensitive to very small residues.
When does an applicator know that the cleaning job was good enough? In about two weeks! There is no easy way to tell, except to be precautionary.
A bit of math can help put us in the ballpark. First, we need to know the tolerance of a crop to the herbicide, preferably expressed as a proportion of the tank mix to be cleaned. Let’s use dicamba as an example. It’s been reported that non-dicamba tolerant soybeans can show leaf-cupping symptoms from dicamba at rates as low as 1/20,000 of the label rate.
Recall that sprayer cleanout is really two separate processes that we’ve written about here, here, and here. The first is dilution of the remaining volume in the system. The second is decontaminating specific sprayer components (filters, boom ends, hoses). We’ll focus on dilution in this article.
If you’re diluting, the second piece of information you need is how much liquid is left in the sprayer when you start cleaning. All sprayers have a certain amount of liquid left in the tank and associated plumbing after the tank is empty. The sump, the suction line feeding the pump, and the lines returning to the tank via agitation or sparge are most common. Even when the pump no longer draws liquid, those lines retain some volume of product. This volume can’t be pushed out to the boom, most of it goes back to the tank.
The volume of this “remaining liquid” is likely somewhere between three and thirty US gallons.
The remainder volume depends on the sprayer, and also how the tank is emptied. Some applicators simply spray until the solution pump pressure drops, others choose to drain the remaining liquid from a sump valve. When draining, product should be captured in pails rather than allowing it on the ground where it will harm the soil and possibly make its way into runoff.
It’s always preferable to spray the tank empty in a field.
As we’ll see below, a low remaining volume greatly improves the efficiency of the dilution process. It’s a sprayer feature that should be considered at purchase.
The table below has some sample calculations. Note that the paired cases (1&2, 3&4, 6&7) all use the same total water volume, but compare a single vs triple rinse of three different remaining volumes.
Comparing Case 1 to Case 3 or Case 6, (remaining volumes of 10, 20, and 50, respectively), it’s clear that minimizing the remaining volume is important.
It’s also striking that the same amount of clean water, subdivided into three smaller repeat batches (Case 2, 4 and 7), is much more powerful than using single batches with the same total clean water amounts.
Reducing the size of each batch even further and increasing the number of batches (Case 5) approaches what a properly executed continuous rinse can do.
Is it necessary to dilute to the level that’s safe for the next crop? Not always. The next product in the tank acts to dilute the remainder once again, possibly by a factor of 100, depending on the remaining volume and the tank size (Case 8). The material in the boom, however, won’t be diluted by this additional volume, and therefore may harm the crop unless it is first sprayed out elsewhere, especially when section ends are not drained and rinsed.
This is where a recirculating boom is valuable, providing an opportunity to charge the boom without spraying. The penalty is that the boom volume is then returned to the tank in the process, increasing the amount that needs to be diluted.
Let’s return to the dicamba example with a 20,000-fold dilution requirement and a 1,200 gallon tank. We’ll consider two examples. In the first, the operator wants to prime the boom in the soybean field without any harm to the dicamba-susceptible beans. A 20,000-fold dilution is needed.
We’ve looked at five options that each assume a remaining volume of 10 gallons. Note that our goal is the same – dilute by a factor of 20,000.
The formulae:
Dilution per Rinse = final dilution ^(1/# of rinses)
Rinse Volume = (dilution per rinse * remaining volume) – remaining volume
The maximum amount of dilution possible with a 1,200 gallon tank and a 10 gallon remainder is 120 (see Row 8, Table above).
- One rinse diluting by 20,000 – impossible with a 1,200 gallon tank (max achievable is 120-fold);
- Two sequential rinses each diluting by a factor of 20,000^(1/2) = 141. Also impossible with a 1,200 gallon tank;
- Three sequential rinses, each diluting by a factor of 20,000^(1/3) = 27. A volume of 260 gallons can do this (27*10)-10=260 gallons. For three rinses, the total volume is 780 gallons.
- Four sequential rinses, each diluting by a factor of 20,000^(1/4) = 12. A volume of 110 gallons can do this, for a total volume of 440 gallons;
- Five sequential rinses, each diluting by a factor of 20,000^(1/5) = 7. A volume of 60 gallons can do this, for a total volume of 300 gallons.
The first two examples don’t work because the tank isn’t big enough. But the three remaining examples all work equally well, they just consume different amounts of clean water.
If that doesn’t seem like a lot of work, then repeat this calculation with a 30 gallon remainder volume, common on many sprayers. Short on time? We did it for you here.
Second, let’s assume the operator is prepared to prime the boom where it doesn’t harm soybeans. Now the first new product tank takes care of the last dilution, lowering the cleanout dilution requirement by 1,200/10 = a factor of 120. Now the cleanout dilution requirement is only 20,000/120 = 166.
- One 1,200 gallon tank rinse can only achieve 120-fold dilution.
- Two rinses, each diluting by 166^(1/2) = 13. Rinse volumes of 120 gallons are sufficient, for a total of 240 gallons.
- Three sequential rinses, each diluting by a factor of 166^(1/3) = 6. A volume of 50 gallons can do this, for a total volume of 150 gallons.
The math is simple, and can be done using the formula in the first table, or this app:
The hard part is knowing what the remaining volume is. It would be very useful for a manufacturer to provide this information.
In the meantime, you can estimate on your own. Add water with surfactant to your tank, and spray it empty. While spraying, turn the agitation on and off to fill and activate the sparge, if equipped. Once the tank is empty and the spray pressure drops, stop and drain the sump into pails. Ensure that the pump suction line and the pressure line up to and including the agitation and sparge lines also drain. Disconnect these if necessary. If there is a filter housing in this circuit, remove it as well. Avoid collecting liquid from the pressure line beyond where the the agitation or sparge split off, as this will be pushed out to the boom.
An alternative is to estimate the length of hose in this circuit, using the following table as a guide:
And remember, diluting the remaining liquid is only one part of a cleaning process.
February 1, 2018
Continuous Rinsing should be considered in North America
Overview
This article expands on an earlier article: here.
Before we dive into the details, let’s start with a quick video summary filmed by RealAgriculture at Canada’s Outdoor Farm Show in September, 2016.

When the pressure drops and the nozzles begin to sputter, the sprayer is considered empty. However, it can still retain a lot of spray solution. Repeated rinses or tank dumps in the same location can lead to accumulation and cause point source contamination.
In response to unacceptably high levels of environmental pesticide contamination, the European Union published an amendment to their directive regarding machinery for pesticide application (2009/127/EC). Their intention was to raise the standard of equipment design to reduce the standing volume of spray solution, and to improve cleaning practices. In order to comply, sprayer technology and operator practices would have to change. But the the amendment didn’t specify how, or to what level.
France (2006) and Denmark (2009) legislated that a rinsed sprayer must not have more than 1% or 2%, respectively, of the original tank mix concentration, as sampled at the nozzle. In response, P G Anderson et al. suggested that residual concentrations should be sampled from at least three places on the sprayer. They conducted research (download here) that showed that both field and airblast sprayers can retain 10-15% of the original concentration in the empty/fill valves, boom ends and filters, while rinsate measured 1-2% at the nozzle. They also stated that in order for sprayer designers, operators and authorities to comply with these new rules, someone had to develop a simple but robust method for cleaning sprayers.
Continuous cleaning
In a later paper, the author and his team proposed a method called “Continuous cleaning” (download here), which employs a dedicated clean water pump to push spray solution from the tank and out the boom in the field. For comparison, the traditional triple rinse method employs the main pump to dilute the remaining spray solution with clean water in a series of rinses and sprays. You can learn more about point source contamination and rinsing methods in this clear and informative presentation by P. Balsari and P. Marucco (download here) given in 2015 at the University of Turin in Italy.
The continuous cleaning method isn’t new. In the 1970s some farmers cleaned their sprayers by plumbing a water supply hose into the suction line while spraying out the rinsate. They were on to something, because formal testing in the late 1990s showed that continuous cleaning was more efficient than triple rinsing. Then, from 2005 onward, research by groups such as betterspraying aps, TOPPS, the Julius Kuhn-Institut and AAMS further refined the process for both field and airblast sprayers.
Anderson et al. made compelling claims about the continuous cleaning method. They stated that a 4,000 L sprayer with a 400 L clean water reservoir would require only 100 L to clean the plumbing as effectively as triple rinsing, which would require the entire 400 L. The remaining 300 L could be used to rinse the exterior and the entire process could take place in the field, in rotating locations. Perhaps most intriguing of all was that it would only take five minutes.
But, it is important to note that their rinsate samples came from the nozzles, as required by France and Denmark. The issue of higher concentrations in dead-end plumbing is not addressed.
European adoption
In anticipation of the regulations, some manufacturers were already developing continuous cleaning kits to upgrade sprayers of all makes, models and ages. In Denmark (and to a lesser extent in France and Germany) these kits were used at workshops to upgrade sprayers. But, the installation process was not always straight-forward.
Some kits performed better than others and expertise was needed to match the flow rate, tank rinse nozzles and the pump’s power requirements to the sprayers. Depending on the sprayer’s design, it sometimes required trial and error to establish a process of opening and closing valves during rinsing. Independent testing showed that many sprayers were greatly improved,(download here) but others proved incompatible due to the volume or inaccessibility of residual spray mix remaining in the plumbing. Specific cases include dead-ends on boom sections, or exceptionally long return lines on circulating booms
Defining a fit for North America
In early 2016, we wrote a preliminary article describing what we knew of the method and it created a lot of interest. We decided to test it our for ourselves in a demo at the Canadian Outdoor Farm Show. But before we describe what we did, let’s clarify a few terms. You may have noted that in Europe the process is called “Continuous cleaning” but moving forward we will refer to the method as “Continuous rinsing”. This is because we feel cleaning a sprayer and rinsing a sprayer are different processes with different objectives.
“Cleaning” a sprayer is a total decontamination that should be performed when changing chemicals and at the end of every spray day. It requires the use of a detergent and any label-required additive (such as ammonia following the new dicamba products). Perhaps most importantly, it requires the operator to address the dead-end plumbing areas. There is no universally-accepted process, but we describe fairly common protocols for field sprayers here and for airblast sprayers here.
“Rinsing” is a less intensive process intended to reduce the amount of residue that can build up on, or soak into, sprayer surfaces. Water is brought into contact with most of the plumbing to dilute any solution left in the sprayer, and is then sprayed out in the field. This process should be performed every few loads, or when moving an empty sprayer between fields, or if the operator has (perhaps unwisely) decided not to clean the sprayer at the end of the day because they are spraying the same chemical tomorrow. Often, this is accomplished using the triple rinse process, which we describe here:
Triple Rinse Process
1. The pressure drops and nozzles sputter (i.e. spray tank is empty).
2. If the sprayer has an inductor bowl or loading bypass, and if the operator doesn’t already rinse these systems following filling, the operator will exit the cab, open the valve to clean water reservoir, and use a portion of the clean water to clean these circuits. In some cases, the rinse process can be performed without the operator having to leave the cab.
3. Sprayers with dead end plumbing on boom section ends warrant special consideration. Spray mix can be harboured in the dead ends and is a significant source of contamination, no matter how much rinsing is performed (see video). Therefore, the first rinse (step 5) should be interrupted before it is complete to allow boom ends to be opened, flushed and closed.
4. The operator then introduces 1/3 of the clean water reservoir to the spray tank through the rinsing nozzle(s) and circulates for 5 minutes (including the agitation line).
5. The operator returns to cab, and drives to spray the volume out in the field until the nozzles sputter.
6. Operator exits the cab and introduces 1/3 of the clean water reservoir to the spray tank through the rinsing nozzle(s) and circulates for 5 minutes (including the agitation line).
7. The operator returns to cab, and drives to spray the volume out in the field until the nozzles sputter.
8. Operator exits the cab and introduces 1/3 of the clean water reservoir to the spray tank through the rinsing nozzle(s) and circulates for 5 minutes (including the agitation line).
9. The operator returns to cab, and drives to spray the volume out in the field until the nozzles sputter.
The process, illustrated in this field sprayer plumbing animation, takes about 40 minutes and may require the operator to leave the cab multiple times.
Continuous rinsing requires a second pump to be installed in the system. Rather than performing a serial dilution in three batches, this rinsing essentially pushes spray solution out of the sprayer using clean water. The agitation line creates some dilution since it loops back to the tank, but that small volume is quickly diluted by the process, as below:
Continuous Rinse Process
1. Pressure drops and nozzles sputter (i.e. spray tank is empty).
2. If the sprayer has an inductor bowl or loading bypass, and if the operator doesn’t already rinse these systems following filling, the operator will exit the cab, open the valve to clean water reservoir, and use a portion of the clean water to clean these circuits.
3. There can be no dead-end plumbing at the end of boom sections for this process to work (e.g. sections terminate with air-aspirating end caps).
4. The operator returns to cab (if they left), and begins introducing clean water to the tank through the rinsing nozzle(s).
5. When a small volume has been introduced, the operator engages the agitation line with reduced flow to tank and begins driving and spraying at a rate slightly higher than the clean water pump’s flow rate.
6. Operator continues to spray until the nozzles sputter.
The process, illustrated in this field sprayer plumbing animation, takes about 10 minutes and requires the operator to leave the cab once at most.
Building a demo system and model
We worked with HJV Equipment in Alliston, Ontario to build a bench-top model representing a simple, scaled-down sprayer rinse system. Using the model, we planned to compare the effectiveness and the efficiency of triple rinsing to continuous rinsing – and we would do so in front of an audience. HJV felt that to make an appropriate model, we should base it on an installed system. So, they plumbed a working system into a RoGator 700.
They used two Hypro electric roller pumps (model 4101 N-H) in parallel, plumbed into the clean water reservoir. Anti-backflow valves led the water to the tank rinse nozzles. The system could be engaged from the cab and could be isolated from the existing rinse system, leaving the sprayer’s original system intact and available for when full cleanings were required. The designer/mechanic points out key features in the following video.
The RoGator 700 has a 700 US gallon tank and a 50 US gallon clean water reservoir. By tapping into an existing compressor, HJV created a means for blowing out the boom with air, greatly reducing the amount of spray solution left in the empty sprayer. Still, the “empty” sprayer would retain about 15 US gallons in the pump, sump and remaining lines. Based on those parameters, we designed and constructed our scaled model. We used 10 L in the main tank and 4.5 L in the clean water reservoir. The lines and sump held about 1.25 L so we felt breaking the 4.5 L of clean water into three 1.5 L volumes was fair.
In the images that follow you can see the components. Basically we have a spray tank, clean water reservoir, main pump, dedicated clean water pump, the sprayer boom, and some clever anti-backflow and valves to switch the “sprayer” from one method of rinsing to the next.
But, we still had to devise a means to measure the effectiveness of the two rinsing systems. UV dye would be difficult to use with a live audience in real time, and food colouring would be too subjective. We decided to use a conductivity meter, which quickly measures the electrical conductivity of a liquid. Using NaCl (table salt) as a readily-dissolved conductor, we calibrated the unit and found we could reliably register table salt in parts per million.
The demo process
We ran the demo six times over three days and recorded how long each rinse took and how effective each rinse was in reducing the original concentration. Here’s how we did it:
Triple Rinse (~4.5 minutes)
1. Fill the main tank to 10 L.
2. Introduce 10 cc of salt (and coloured with green food dye) to create our spray mix.
3. Circulate the solution through the main pump and agitation line to ensure it was completely homogeneous.
4. Start the system spraying out of the boom.
5. Draw a sample of the spray mix to serve as our baseline concentration.
6. When the nozzles began to sputter, the tank was “empty” (duration: 150 seconds).
7. We drained the boom via valve on the boom-end to simulate “blowing out” the boom. (duration: 5 seconds)
8. We introduced 1.5 L of clean water through the tank rinse nozzle (duration: 15 seconds).
9. We circulated the solution through the agitation line. (duration: 30 seconds).
10. We sprayed the solution out of the boom, drawing a sample of rinsate before the nozzles sputtered (duration: 30 seconds)
11. Repeat steps 8-10 two more times to represent the other two rinses.
Continuous Rinse (~1.5 minutes)
1. Fill the main tank to 10 L.
2. Introduce 10 cc of salt (and coloured with green food dye) to create our spray mix.
3. Circulate the solution through the main pump and agitation line to ensure it was completely homogeneous.
4. Start the system spraying out of the boom.
5. Draw a sample of the spray mix to serve as our baseline concentration.
6. When the nozzles began to sputter , the tank was “empty” (duration: 150 seconds).
7. We drained the boom via valve on the boom-end to simulate “blowing out” the boom. (duration: 5 seconds)
8. We reduced the agitation flow to a low rate and introduced 1.5 L of clean water through the rinse nozzle using our dedicated pump (duration: 5 seconds)
9. At the 5 second mark, we started spraying while still introducing clean water.
10. Samples of rinsate were drawn at regular intervals, with particular attention to collect the last volume fraction as the nozzles were sputtering (duration: 100 seconds)
Results
Triple Rinse
The average starting conductivity for the triple rinse demo was 2,520 µS (n=6). The final sample of rinsate registered a conductivity of 490 µS (n=6) representing a final concentration that was 19.4% of the original. Average time: 4.5 minutes.
Continuous Rinse
The average starting conductivity for the continuous rinse demo was 2,145 µS (n=6). The final sample of rinsate registered a conductivity of 342 µS (n=6) representing a final concentration that was 16% of the original. Average time 1.5 minutes.
We were surprised the model could not reduce the concentration of salt to an acceptable 1-2% level. The Agrimetrix Dilution Calculator App suggests it should have been much better. We suspect the standing volume of the system is higher than we predicted, and we weren’t using enough clean water to dilute it. We may have had better results if we’d used a lower concentration of salt to begin with, and/or a higher volume of clean water. We will continue to tweak the demo model and will update this article as we collect more information. The more stringent research in Europe showed that continuous rinsing is a effective as triple rinsing.
The most interesting result is that continuous rinsing took 1/3 of the time triple rinsing required (1.5 minutes versus 4.5 minutes). Research in Europe suggested 1/4 of the time as triple rinsing. The difference is likely accounted for by the time the operator used leaving and entering the cab.
You can see the effectiveness of the process in this AAMS demonstration video. Sure, their demo unit is nicer than the one we built, but our rustic version has charm 🙂 Note the sequence of opening and closing valves to ensure all circuits are rinsed clear of dye.
Conclusion
If continuous rinsing is as effective as triple rinsing and can be performed in a fraction of the time with less operator exposure, then we should be modifying our sprayers to support the method. Airblast sprayers and small field sprayers are relatively easy to modify, and can be even be equipped with a spray wand so excess clean can be employed to rinse down the exterior.
Larger field sprayers, however, may be more challenging as they do not all lend themselves to the conversion:
- The clean water pump (hydraulic or electric) must have sufficient power.
- Matching the pump capacity to the sprayer can be problematic; The clean water pump flow rate must be 30-50% of the boom flow rate.
- Sprayers with dead-end boom sections or circulating-flow return lines may not be compatible, and those with pneumatic systems to clear the boom of solution are preferred.
- More sophisticated electronic rate controller systems (e.g. on the larger self-propelled sprayers) may not be compatible.
And, of course, we must remember that neither triple or continuous rinsing should be seen as a replacement for the sprayer cleaning process. Any drain-able part of the sprayer will still harbour high concentrations of residues (e.g. filters, valves, inductors, bypass lines – any dead-end plumbing). With new stacked chemistries being introduced in North America (some still active when residues register as little as a few parts per million), diligent sprayer sanitation is more important than ever.
Thanks to Jan Langenakens of aams for his help researching and informing this article.
October 2, 2016
Continuous Rinsing
We’ve recently been talking about how to save time while cleaning a sprayer. Although it’s very important to be thorough while cleaning, and to take the necessary time to do the job properly, there is always an opportunity to fine tune and spend less time. This is especially true when diluting the tank remainder down and pushing clean water to the booms. A method promoted in Europe, and coming to us via Joachim Herfort of Agrotop, is called “Continuous Rinsing”.
Continuous Rinsing requires a dedicated pump that delivers the clean water (which may contain a cleaning adjuvant) to the tank via wash-down nozzles. It works like this:
1. The operator, having carefully measured the pesticide mixture, has only a small remainder in the tank when spraying is complete.
2. This remainder is sprayed out in the field, either on a set-aside area, or over the already sprayed field at a reduced rate, product permitting (the operator would pay attention to crop tolerance and carryover issues)
3. As soon as the tank is empty, indicated by the boom spray pressure dropping, the operator switches on the clean water pump which delivers the clean water via the wash-down nozzles.
4. Soon, the main product pump starts delivering the wash-down liquid to the boom and the return lines.
5. Because the clean water pump will deliver less than the boom flow, the cleaning mixture is delivered somewhat intermittently. We are told that this helps with the cleaning action of the lines. Be cautious that the main pump does not run dry long enough to damage its seals.
6. Once the clean water tank is empty, the pressure drops again for the final time and the tank rinsate is now very dilute.
7. Testing in Europe has shown that the whole process takes only about half as long as batch mode. One key time-saving feature is that the sprayer never has to stop, and the operator never dismounts. These data also show that a significantly lower water volume is required to achieve a greater dilution of the remainder than a batch mode would have achieved.
8. For example, the European tests (we believe these were done by the Landwirtschaftskammer of Nordrhein-Westfalen, a German regional government) used a single rinse of 80 L, as well as four batch rinses of 20 L each. As expected, the four-batch process was superior to the single rinse, but took a lot of time. They then tested a continuous rinse with 40 L. The continuous rinse resulted in greater dilution than the 4 x 20 L rinse, in less time. In this case, the quality went up, and the time went down.
Our challenge in North America is to roughly match the clean water pump, wash-down nozzles, and main sprayer pump capacities so the system works. Our larger sprayers easily deliver 30 gpm, and some adjustments may be necessary.
Dilution of the tank remainder is only one aspect of sprayer cleaning. The other aspect, decontamination of surfaces and components, is also important and the process depends on the active ingredients and formulations in the tank.
An animation developed in Germany and shared via Agrotop is available here.
Note that Agrotop has suggested components to convert a sprayer to a continuous rinse system here.
March 22, 2016