PWM on sprayer

[Secret Agronomist]

Thinking about a new sprayer, probably SP. PWM (Capstan system) seems like a no brainer to me, individual nozzle control, turn compensation, no need for lots of air pipes along booms. Seems like you cant lose
So any negatives? We are running a trailed just now with auto section control (8 sections over 36M) but we obviously still get overlaps on headlands, especially with fertiliser.
Also anyone using PWM with liquid fert?

 

[Steevo]

Negatives....the price?!

 

[Secret Agronomist]

Might not be too terrible on a new machine by the time you delete 144 air shutoffs and dribble bars, much to ponder. Plus theres the ability to run at varying speed, which will help on a a lot of our fields which vary from 3 to 40 ha, so going slow for the headland then speeding up in the middle.

 

[Bobthebuilder]

Suppose it depends on how you do your corners, stop n back into them or keep spraying as you turn, seems a huge cost for not a huge benefit with GPS and auto shut off you shouldn't be getting too much over spray

 

[Robt]

I think the need is most definitely there for booms over 24m. Even on a modest curve the inside boom will travel at quite a different speed to the outside one thus under or over dosing.

 

[pokmo]

Anyone know why PWM sprayers cost so much though? Do PWM nozzles really cost that much more than conventional ones?

 

[Gav]

It’s not just different nozzles that are used with PWM systems, it’s all the extra solenoids and electrics that control each nozzle as well that adds to the price.

 

[Brisel]

I slightly wish we'd specced PWM on our last new 36m sprayer. Curving headlands are hard to dose correctly and that's how weeds seem to get into the field as you need full rate herbicide for control for some. We could be breeding resistance into them with under dosing and overdosing kicks the hell out of the crop.

Most of the cost is down to the additional hardware required to modulate the flow. That has to talk to rate controllers etc too.

I can't see any reason that dribble bars wouldn't work with PWM, though it's a bit crude where you've got some low pressure piping between the metering unit and the bar nozzles. It's air induction nozzles that don't work with PWM as it disrupts the air flow into the mixing part of the nozzle body.

 

[snarling bee]

If there is a curved headland on the way back to the gate I would make sure it had another half dose of chemical. Not always possible though.

 

[pokmo]

It’s not just different nozzles that are used with PWM systems, it’s all the extra solenoids and electrics that control each nozzle as well that adds to the price.

Right. Do you know how much more PWM solenoids cost? AFAIK, PWM solenoids used in automatic transmissions cost just around £20 each.

 

[Hobbit]

It was a 26k+ extra on a new 30m Bateman. Brilliant system but I couldn’t justify it this time. Hopefully the price will come down when the tech becomes more common, or is that wishful thinking

 

[Hampton]

Might not be too terrible on a new machine by the time you delete 144 air shutoffs and dribble bars, much to ponder. Plus theres the ability to run at varying speed, which will help on a a lot of our fields which vary from 3 to 40 ha, so going slow for the headland then speeding up in the middle.

It cost about 10-15% on top of the sprayer price

 

[Db880]

So a question, pwm and use with fert I was always lead to believe that the most important thing is not to break the stream, either delivered by dribble bar or nozzle of some description. Pwm by the way it works is turning on and off the nozzle many times per second. So surely breaking that stream and not having a constant would be a bad thing for fert?

happy to be told otherwise but it’s the way I see it.

 

[Brisel]

So a question, pwm and use with fert I was always lead to believe that the most important thing is not to break the stream, either delivered by dribble bar or nozzle of some description. Pwm by the way it works is turning on and off the nozzle many times per second. So surely breaking that stream and not having a constant would be a bad thing for fert?

happy to be told otherwise but it’s the way I see it.

There's a risk that you will break the streams up but remember that you're lowering the dose where you'd be overdosing in the past without PWM which would cause scorch, lodging etc, so overall you're still better off IMHO.

 

[Billericay Farm services]

See attached our very popular UK made BFS PulZar PWM nozzles

 

[JRA]

@Brisel I understand you have moved in recent months so might not apply to your previous machine, but we are able to retrofit the Raven Hawkeye PWM system. We are just in the process of upgrading some none Chafer machines as well, so not only limited to our yellow machines.

 

[Hampton]

@Brisel I understand you have moved in recent months so might not apply to your previous machine, but we are able to retrofit the Raven Hawkeye PWM system. We are just in the process of upgrading some none Chafer machines as well, so not only limited to our yellow machines.

Ballpark cost for a 24m guardian please?

 

[JRA]

Ballpark cost for a 24m guardian please?

@Hampton you would be looking somewhere in the region of high teens or low 20s for this I would think, depends on existing control systems, flow meters, nozzle bodies etc. If you would like a more accurate price, drop me a DM with your machine serial number and I'll work something out.

A bit more information on the Raven system can be found here - https://www.cropsprayers.com/chafer/new-crop-sprayers/options/pulse-width-modulation-pwm/

 

[Oscar]

Only just seen this thread . It's a brilliant system and been in States / Canada for 15 plus years. I ve used it over there ,however it's too dear in my opinion and does not work with liquid fert on dribble bars at least .
If you farm a big area and pay for the chemical , then maybe over a 5 year period , the saving in chem from individual control and better application on bends MAY go towards paying for it but for someone like me doing contact work , it just adds £25 k plus to the cost of the machine and can t charge anymore for doing the job so unfortunately I chose to not add it to my recent new machine .
Apparently the Capstan system is now offering a section system rather than individual nozzle to reduce cost but not sure if available yet.
Another thing to ponder is like most tech , just because it's possible or now available does nt always mean its needed and makes yet another possible problem to encounter when you want to go spraying and the tech says NO ( I ve been there , first decent day, lots to do ,go out, switch on and some tech has a red cross in stead of a green tick, nothing works , usually on a Sunday or bank holiday !!! )

 

[Hjwise]

Suppose it depends on how you do your corners, stop n back into them or keep spraying as you turn, seems a huge cost for not a huge benefit with GPS and auto shut off you shouldn't be getting too much over spray

Not sure if you can just swing round at the corners - don’t they have a specific range in the differential between the inner and outer nozzles?

I’ve still yet to figure out how auto shut off saves chemical. A recommendation of 1l/ha on 10 ha field will get 10l applied auto shut off or not. There is an argument that the field is being under-dosed to make up for the overlaps. But it’s largely insignificant in my opinion given that most applications are not full rate and therefore quantity is just someone’s judgment.