Suitable pressure for a three point linkage sprayer

[FordnMassey]

Hi,

I have some questions around a three point linkage sprayer. It's around 40 years old and was on the property when I bought it and I suspect it was set up for spraying grape vines. It has a Bertolini pump 31L / 9galUS at max pressure and 10 nozzles @ 50cm/20" on 2 booms. The pressure regulator runs up to 100bar, (yes one hundred), and has a green zone up to 40 bar. The nozzles are clearly the age of the machine, are orange and have a "shroud" around them that air is drawn thru when spraying, and they create a fine mist. Run at 20 bar the spray is a fairly fine spray, and at 40 bar it's a mist. At both pressures each nozzle produces 4 L (1galUS) per minute. I'm intending to use the sprayer on 30 acres for glyphosate application on rough, steep paddocks where 4kmh/ 2.5mph is as fast as can be traveled safely. My calculations make that 2ha /4.5ac an hour and that will apply 2400L/685 galUS an hour, so 1200L/Ha or 340 galUS/ac.

My questions are:

1). anyone have any experience with pressures like this on spray units?

2). What were or are those pressures used for?

3). What was such a heavy rate of application used for?

As always, thanks in advance for your help

 

[old and tired]

"...Suitable pressure for a three point linkage sprayer..." usually between 15 psi to 70 psi, depending on what spray coverage you need and also what the nozzles are at the tip. Nozzles have ranges of PSI that will put out different droplet sizes depending on pressure. That range is for most herbicides and insecticides.

Herbicides are normally lower pressure, larger droplet sizes to cover the leaf surface. Insecticides are used at higher psi and need smaller droplet sizes to penetrate the canopy to reach the insects.

"...At both pressures each nozzle produces 4 L (1galUS) per minute..." I question how you determined this... also, we usually ask, do you have photos of this sprayer and pump...

40 years old, my guess, the pressure gauge is not working correctly. I would also assume the spray tips are past their prime, do you know what size they are?

If it is working, it seems to me that you might be dealing with a power washer pump for cleaning equipment or fire fighting equipment. Again, photos would answer a lot of questions.

I've been mixing chemicals and spraying for 35 years - if you need help to calibrate it, let me know.

One side note: There was someone on TBN that used to use one of the IBC totes to apply RoundUp. He used 300 gallons to cover an acre and added the correct amount of RoundUp (on the label) and it worked out perfect for him.

I also know aerial applicator that spray chemicals down to 2 gallons of water per acre... both work, but you need to know what your sprayer puts out so you can mix the correct amount of chemicals...

 

[CloverKnollFarms]

It's not how much fluid goes down, it's what the chemical concentration is. You can apply 64oz of Trimec per acre in 25 gallons, or 50 gallons of water. Same rate of chemical, different volumes of solution.

 

[rgr33]

I am unsure , from your description, what kind of sprayer you have. Pictures would be very helpful here.
Is it an airblast, or boom type?

 

[FordnMassey]

Hi,

Sorry for the initial lack of pictures, I've added some here.

The sprayer is a boom type. I measured the output of each nozzle by running the sprayer at running speed, 540rpm pto, and holding a bucket under each nozzle. There was 1.5-2L (0.4-0.6USgal from each nozzle in 30 seconds.

The pressure regulator and it's gauge are new and working properly. It is a direct copy of what was on the machine as I was able to buy the exact model again as a spare part. There's a photo attached of the new regulator.

I'm comfortable with the calculations to manage the rates of chemical application, but on hilly, rough paddocks I'm interested in lower volumes to make it safer to do.

Thoughts on the questions in the first post?

FordnMassey

 

[old and tired]

Still a bit hard to see but thanks for the photos.... Do you have anything to use as a bypass regulator or a relief valve? Like this one: "TeeJet 23120 bypass regulator"

What it does, it takes excess pressure and just returns it to the tank. You'll have less pressure to the noozles which reduces the spray volume so you can drive slower.

 

[CloverKnollFarms]

I mean, you can always change the tips. I've got different tips for different chemicals.

 

[FordnMassey]

Thanks Ild and Tired and Clover Knoll Farms for the input.

The regulator does have a bypass valve. The problem with lower pressures on these nozzles is that below 20 bar the nozzle outputs progressively degrade to become a narrow fan of big droplets which will give poor coverage.

I think the idea of different nozzles for different chemicals may be the answer. I'm coming to suspect that this sprayer was configured for Bordeaux mix. I'm having difficulty finding information on it's application, but I suspect it was applied at high volumes per ha/ac and as a mist to achieve good coverage.

I suspect that I will replace the nozzles.

Thanks for your help. It moved me forward in understanding how I can use this sprayer.

FordnMassey

 

[old and tired]

Just to add more information (for people searching in the future...)

You could use the sprayer as is, figure out at what pressure your sprayer applies a good spray coverage (if it doesn't spray well enough at any pressure, then yea, get different nozzles!!)

Then fill up the tank, figure how much plain water you use to spray the area you want to spray at the same constant speed you want to be at (slower is fine). You'll just use more water.

Then calculate the amount of area that you just sprayed with water, then mix the chemical based on that area.

Anyway; Just know that Glyphosate is pretty corrosive and the sprayer/pump should be thoroughly cleaned. I go as far as to open the pump (unscrew the cover) and clean/dry all the surfaces inside. I used to rinse with water then pour oil into the pump but I almost lost a pump - it didn't work without cleaning it more. So I take the extra step to clean the pump.

For RoundUp/glyphosate spraying, I would look for "flat fan" nozzle tips - I've only used Teejet brand. They come in angles, 80* or 110* (depending on nozzle spacing and height of boom) some are design to over lap the spray of the next nozzle; some spray an even pattern across the bottom (no overlap needed). I think 80* works for 20" spacing between nozzles.

The nozzles are also designed for different "gallons per minute". For those that want to know everything about spray nozzles but were afraid to ask...

https://www.teejet.com/-/media/dam/agricultural/usa/sales-material/product-market-bulletin/li-tj416_user-guide-to-spray-technology.pdf

That publication is also a cure for insomnia....

EDIT: even at 5 bars - that is a powerful pump!!!!

 

[CloverKnollFarms]

I use the air in induction twin turbo tjet tips for systemic herbicides. They spray two different directions to better contact foliage. Look up your pressure and ground speed and you can find the tip for the rate you desire