Correct Spraying Rate on a small sprayer

DavidHammond123

Member
Trade
Hi, this might be an odd question because I'm an engineer, not a farmer...

How do people make sure they are spraying at the correct application rate on small sprayers (<500l like this one: https://www.silvannz.co.nz/silvan-sprayers/eco-500l-linkage-sprayer/)?

From what I've seen they just have a physical pressure gauge.
So the application rate could be calculated using the calculation table supplied with their nozzle tips, along with the pressure reading, and driving speed, right?

What about when driving along, does the pressure ever change?
Would it be hard to make sure the application rate stays true while driving since the pressure gauge is behind the operator?

How common is it to have a monitor/controller on a sprayer like that?

Thanks,
Dave
 

DavidHammond123

Member
Trade
Thanks @Zebbedee.
I have a follow-up question, I was under the impression that the PTO was a steady RPM regardless of engine RPM, is that true or is it proportional to engine RPM?
I've seen these sprayers with PTO pumps and some smaller ones with 12V electric pumps, is the pressure controllable at all like with larger sprayers? (Or is it just whatever pressure the pump puts out)

Just wondering if you can't change the pump pressure then the tips or driving speed would have to be changed to get the correct rate.
 

Boysground

Member
Mixed Farmer
Location
Wiltshire
Pto speed is relative to engine speed. Most machines rely on a 540 rpm pto speed which will normally be about 1800 rpm. Often sprayers don’t need that much speed. Get to the revs you like, put it in gear and stay there.

This may helphttps://www.syngentaturf.co.uk/file/1586/download

There’s bound to be other crib sheets on tinternet

Bg
 

Nukemall

Member
There is also normally a pressure regulator on the sprayer, looks like it is the blue twist knob next to the pressure gauge on the sprayer in your link. This allows you to increase or decrease pressure with your pto at a constant speed, allowing you to select the correct gear and revs to give you a known forward speed on your tractor (if it doesn't have a speed display on the dash).
 

DavidHammond123

Member
Trade
Thanks for the responses everyone.
I have worked on larger sprayers that have flow meters and flow control valves, so I'm more used to the calibration calculations being from flow rather than pressure.
Cheers for that document as well, that made sense.

I've been thinking of making something that measures the pressure and driving speed to calculate the application rate 'live'.
Just a simple monitor really, I can't find a monitor like this online but my google skills might be failing me.

Does/would anyone use a monitor like this? I know controllers on larger sprayers are super common along with section control, coverage mapping etc.
More thinking of a monitor just so the product isn't over/under applied for these small sprayers.
 

adam_farming

Member
Arable Farmer
Location
Suffolk
Thanks for the responses everyone.
I have worked on larger sprayers that have flow meters and flow control valves, so I'm more used to the calibration calculations being from flow rather than pressure.
Cheers for that document as well, that made sense.

I've been thinking of making something that measures the pressure and driving speed to calculate the application rate 'live'.
Just a simple monitor really, I can't find a monitor like this online but my google skills might be failing me.

Does/would anyone use a monitor like this? I know controllers on larger sprayers are super common along with section control, coverage mapping etc.
More thinking of a monitor just so the product isn't over/under applied for these small sprayers.

That would be interesting to see. I have an older sprayer and tractor and just drive at the right speed for what the pressure gauge says. For example I'm on yellow nozzles so know that when spraying at 2.2bar, about 8kph is needed for 100l/ha. To make it slightly more accurate I use a GPS speedometer on my phone which helps a bit.
 

DavidHammond123

Member
Trade
That would be interesting to see. I have an older sprayer and tractor and just drive at the right speed for what the pressure gauge says. For example I'm on yellow nozzles so know that when spraying at 2.2bar, about 8kph is needed for 100l/ha. To make it slightly more accurate I use a GPS speedometer on my phone which helps a bit.

I was thinking of making a box that the pressure sensor feeds into.
Then the box would have a Bluetooth connection to a phone.
On the phone, I'd have an app that uses the GPS speed of the phone along with the pressure reading + nozzle tip width + nozzle pressure to flow rate value(from nozzle manufacturer).
Do the calculations and then show on-screen the Application Rate as it changes.
 

adam_farming

Member
Arable Farmer
Location
Suffolk
I was thinking of making a box that the pressure sensor feeds into.
Then the box would have a Bluetooth connection to a phone.
On the phone, I'd have an app that uses the GPS speed of the phone along with the pressure reading + nozzle tip width + nozzle pressure to flow rate value(from nozzle manufacturer).
Do the calculations and then show on-screen the Application Rate as it changes.


Interesting. Keep us updated
 
I was thinking of making a box that the pressure sensor feeds into.
Then the box would have a Bluetooth connection to a phone.
On the phone, I'd have an app that uses the GPS speed of the phone along with the pressure reading + nozzle tip width + nozzle pressure to flow rate value(from nozzle manufacturer).
Do the calculations and then show on-screen the Application Rate as it changes.
You are complicating something that is very simple 😅😅😅
 

bravheart

Member
Location
scottish borders
The sprayer in your opening link is what it is for a reason, small and cheap. You then add on any toys you want at cost. So probably the cheapest way to alter output(pressure) on the move is a motorised valve in place of the blue valve mentioned earlier.
Once you add that you can then make a box of tricks that will make calculations from your inputs, nozzle output number etc. do what you want. Forward speed input bluetooth if you like wheel speed sensor the simplest.
Any toys you add will have a cost and it's not rocket science RDS, teejet and many others have been making such boxes for years. A bluetooth app may be different and keep cost down do your research.
 

Exfarmer

Member
Location
Bury St Edmunds
The rate will not change significantly , if you keep with in 10% of your target speed with in a set gear. This is of course providing you do not have a tractor with either hydrostatic transmission or PTO.
Select a gear which your tractor is comfortable to give the target speed, say 10k set the desired pressure at the chosen rpm used to attain the target speed then off you go..
If you are concerned about the performance do trial run with clean water.
As the RPM drops a fraction so too will the pressure which will offset the speed drop and resultant increase in dosing..
The reverse is true if you go overspeed as say in going up and down hill. If at any point you need to change the gear then you must reset the pressure. It is vital that you choose a gear which you can stay in at all times, during work.
Do choose a speed and pressure where your nozzles give a good fan and carry the sprayer at a hieght to ensure the double overlap.
Hydrostatic transmissions are not really suitable for this type of sprayer as in many garden style tractors
 

DavidHammond123

Member
Trade
The sprayer in your opening link is what it is for a reason, small and cheap. You then add on any toys you want at cost. So probably the cheapest way to alter output(pressure) on the move is a motorised valve in place of the blue valve mentioned earlier.
Once you add that you can then make a box of tricks that will make calculations from your inputs, nozzle output number etc. do what you want. Forward speed input bluetooth if you like wheel speed sensor the simplest.
Any toys you add will have a cost and it's not rocket science RDS, teejet and many others have been making such boxes for years. A bluetooth app may be different and keep cost down do your research.

In my day job, I work at a company that makes controllers for machinery (sprayers/drills/spreaders etc).
Our controllers are capable of doing the full shebang which means they cost a bit of money, which means they are only worth it on larger machinery because the ROI is there.

I have been daydreaming about different solutions using a phone as a screen and Bluetooth (to keep screen and cable/wiring costs down) for these small sprayers (or drills/spreaders), but I'm not sure if the ROI is there for farmers to be worth it. (I also wasn't sure if I was understanding sprayer pressure correctly)

For example, this is just made up numbers because I don't know what they actually are:
Say a farmer with a sprayer like this used 1000 quid of chemical a year to spray
If a monitor/controller decreased his error by spraying error by 10%, that would be a savings of 100 quid a year.
So if this monitor/controller cost 500 quid then it would be a 5-year payback.
Obviously, this would have to last longer than 5 years to be worth it for the farmer.

I'm on the engineering side so I have no idea yet if those numbers are even within a stone's throw of plausibility.

Basically, I'm trying to figure out if I can make something that is cheap enough and useful enough for someone with a small sprayer like that.
 

Boysground

Member
Mixed Farmer
Location
Wiltshire
I once had a Berthoud sprayer with a piston pump (no diaphragms) as long as you stayed in the same gear the speed could be altered with the revs and the rate would stay spot on, it really was very good. Simple and never caused problems. I always wondered why others manufacturers didn’t do something similar.

Bg
 

DavidHammond123

Member
Trade
The rate will not change significantly , if you keep with in 10% of your target speed with in a set gear. This is of course providing you do not have a tractor with either hydrostatic transmission or PTO.
Select a gear which your tractor is comfortable to give the target speed, say 10k set the desired pressure at the chosen rpm used to attain the target speed then off you go..
If you are concerned about the performance do trial run with clean water.
As the RPM drops a fraction so too will the pressure which will offset the speed drop and resultant increase in dosing..
The reverse is true if you go overspeed as say in going up and down hill. If at any point you need to change the gear then you must reset the pressure. It is vital that you choose a gear which you can stay in at all times, during work.
Do choose a speed and pressure where your nozzles give a good fan and carry the sprayer at a hieght to ensure the double overlap.
Hydrostatic transmissions are not really suitable for this type of sprayer as in many garden style tractors

Interesting, that sounds almost like a ground drive spreader.
Like as you speed up/slow down, the rate increases/decreases to compensate.
 

Muddyroads

Member
Location
Devon
If you want to be accurate with the sprayer it’s better to do a jug test on at lest 1 nozzle from each section rather than rely on information tables. Nozzles can either wear of gradually block depending on products being sprayed. Measure the flow per minute at standard PTO speed. This is the most important bit of the calibration process along with nozzle spacing and forward speed.
 

Kidds

Member
Horticulture
In my day job, I work at a company that makes controllers for machinery (sprayers/drills/spreaders etc).
Our controllers are capable of doing the full shebang which means they cost a bit of money, which means they are only worth it on larger machinery because the ROI is there.

I have been daydreaming about different solutions using a phone as a screen and Bluetooth (to keep screen and cable/wiring costs down) for these small sprayers (or drills/spreaders), but I'm not sure if the ROI is there for farmers to be worth it. (I also wasn't sure if I was understanding sprayer pressure correctly)

For example, this is just made up numbers because I don't know what they actually are:
Say a farmer with a sprayer like this used 1000 quid of chemical a year to spray
If a monitor/controller decreased his error by spraying error by 10%, that would be a savings of 100 quid a year.
So if this monitor/controller cost 500 quid then it would be a 5-year payback.
Obviously, this would have to last longer than 5 years to be worth it for the farmer.

I'm on the engineering side so I have no idea yet if those numbers are even within a stone's throw of plausibility.

Basically, I'm trying to figure out if I can make something that is cheap enough and useful enough for someone with a small sprayer like that.
To be honest I can't imagine any sensible person to realistically expect those sprayers to last 5 years nor would they be the type of operators that would be working at an expected 10% error. Their own miscalculations and misunderstanding of how to calculate in the first place will be give more than 10% error.
Might sound harsh but loads of posts on here of professional farmers asking how much chemical to put in a sprayer to do two fields. No idea how much water the sprayer holds, no idea of sprayer output or even a realisation it can vary or matter, no idea of tractor speed and no more idea of area of the fields other than some random thing like "well I put two bags on the first one each year and the other is about three rounds more but gives less bales most years"

Those cheap sprayers are plenty accurate enough and will do a good job as they are as long as you know how to use one. Nothing particularly difficult about it either, in your own words you have found a solution for a problem that doesn't really exist.

Go and build me a cheap PU realtime monitor for in bottle pasteurising with multiple senders wifi or bluetooth linked to a central datalogger/monitoring device. Make sure it has alarms that operate on various settings, ie. 60PU to 1000PU.
PU = (time in minutes) x 1.393 exp(T-60), where T is the temperature in Celsius.
 

bravheart

Member
Location
scottish borders
You may need to find out who buys these sprayers and why. I thought(may be wrong here) anyone selling cereals through a quality scheme needed a certificate on the sprayer which included a working rate controler so anybody buying one in your link is only going to spray a bit of grass and buying that sprayer on price.
 

Top cereal and oilseed growers honoured at the Yield Enhancement Network Awards 2021

  • 522
  • 0
Despite an average growing year for most crops, many growers managed to go above and beyond their predicted max yields, with Lincolnshire grower Tim Lamyman taking the top spots for his wheat yields and his world record breaking winter barley yield.

The highest cereal and oilseed yields achieved at harvest 2021 were announced at this year’s Yield Enhancement Network (YEN) Awards on Wednesday 24th November at the Croptec Show. With award presentations by Tom Bradshaw, Vice President of NFU, 24 farms took home the evening’s top awards for highest yield and highest potential yield achieved for wheat, winter and spring barley, oats, and oilseed. The 2021 winners came from all corners of the UK, as well as from as far afield as Finland and New Zealand.

Familiar names from 2020 made the...
Top