Continuous Rinsing

Dr. Jason Deveau ● OMAFRA Application Technology Specialist ● 2017

• An “empty” sprayer can still retain a lot of standing volume.

• In some large sprayers, the lines, sump and pump can easily retain 20 gal.

• Repeated rinses (or tank dumps due to bad math) in the same location are a significant source of surface water contamination.

France (2006) and Denmark (2009) legislated that a sprayer cannot leave the field with >1% or 2% (resp.) of the original tank mix concentration...

…as sampled at the nozzle.

This is significant because research showed that sprayers can retain 10-15%

of the original concentration in empty/fill valves, boom ends & filters...

P.G. Anderson et al. 2010

…while rinsate still measured only 1-2% at the nozzle.

So let’s define some terms:

Cleaning: Total decontamination performed when changing chemicals, moving into sensitive crops, and at the end of every spray day.

Requires the use of a detergent and any label-required additive.

Requires the operator to address filters and dead-end plumbing areas.

You’d be amazed at what accumulates in sagging lines and boom ends…

Ph

oto

: HJV

Eq

uip

men

t.

Helmut and I delivered this demo at the Outdoor Farm Show in 2015.

And yet, boom ends are STILL a big deal. As of Feb. 9 2017, ~25% still

have dead-ends with caps.

Feb 8, 2017

Each section end can bleed residue into the spray as the boom charges.

And, if using new dicamba products, cleaning cannot be ignored.

Photo: Paul Van Den Borre… but he didn’t do this.

Rinsing: Dilutes residual spray mix, but does not address dead-end plumbing.

Should be performed every few loads, when moving empty sprayer between fields, and at minimum if the operator has (unwisely) decided not to fully clean the sprayer at the end of the day.

The power of dilution

Dilution Factor = Rinse volume + Remaining spray mixRemaining spray mix

• A single rinse of 150 gal. to 20 gal. leftover mix: Dilution factor of 8.5.

• But, serial dilution means 50 gal. to 20 gal. leftover, three times: Dilution factor of 3.5 x 3.5 x 3.5 = 43!

Triple Rinse

Clean water mixed with spray mix, then sprayed out. Three serial dilutions.

• If I can’t convince you to clean daily, perhaps I can convince you to rinse more regularly…

• Who wants to do a 30-40 minute triple rinse multiple times a day?

• No one. But what if there was a faster and easier way?

Rinse more often!

• Europe has adopted a different way to rinse.

• By adding a small dedicated pump, clean water moves directly to the rinse nozzles while the main pump sprays the rinsate.

Continuous Rinsing

1. Minimize remainder (accurate mixing).

2. Engage rinse pump as pressure drops (in field).

3. Let it build up a bit, then drive and spray.

4. Ensure pump capacity slightly less than boom rate (air bubbles help).

5. Spray until empty.

Method

Continuous Rinse

Clean water pushes out spray mix from behind.

Research in Europe showed continuous rinsing reduced residue at

the nozzle to 2% in far less time, without the operator leaving the cab.

Working with HJV, we modified a RoGator 700 for Canada’s Outdoor

Farm Show in 2016.

1 - From fresh water tank via existing lines to a manifold…

2 – …into two, 7.5 gpm (@50 psi) electrical roller pumps…

3 - …through backflow prevention valves… 4 - …teed into the existing rinse system.

• Electrical pumps were cheaper, but if there’s capacity, hydraulic pumps may have better flow rates.

• Engage bypass briefly near the end to ensure lines are diluted.

• Critical to ensure correct flow rate to boom.

Lessons Learned from Install

CleanWater

Tank

Boom

MainPump

RinsePump

Sample Testing

Conductivity: We could quickly detect salt residue in the parts-per-million

range.

We used food colouring to make dilutions more obvious

• The Agrimetrix Dilution Calculator suggests residues should have been much lower than ~15-20%.

• Let’ say a sprayer has a 150 gal. clean water reservoir and 20 gal. left in the lines.

• Our model has 1.5 L left in the lines, so to be fair we should have used ~10 L of rinse water.

…it’s only a model.

Remember

• The biggest result here is that it took <1/3 of the time vs. 3x rinsing… never leaving the cab.

• That translates to ~10 minutes versus 30-40.

• Perhaps if detergent (or ammonia) was added to the clean rinse tank, it might be better still… we’ll explore it this summer.

• Secondary pump flow rate must be 30-50% of the boom flow rate.

• Sprayers with dead-end boom sections may not be as compatible.

• Some sprayers harder to retrofit than others.

• Doesn’t replace cleaning.

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.

Tom Wolf

@nozzle_guyJason Deveau

@spray_guy

Learn more about spraying

www.sprayers101.com