# How to reduce pressure on Chapin 20v backpack sprayer?



## Green (Dec 24, 2017)

I would like to reduce the pressure on the 20v backpack sprayer. The relatively high default pressure is higher than I prefer. What can I do to reduce it? Different nozzle? Some kind of pressure regulator?


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## stotea (Jul 31, 2017)

CF Valve would do the trick. You can get them in 15, 21, and 29 PSI flavors.
https://www.oescoinc.com/constant-flow-valves-cfvalves-for-spray.html


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## g-man (Jun 15, 2017)

What is the issue? Mist?


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## Green (Dec 24, 2017)

g-man said:


> What is the issue? Mist?


Exactly.


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## Ware (Jan 28, 2017)

Green said:


> g-man said:
> 
> 
> > What is the issue? Mist?
> ...


If mist is the issue I would consider switching to an air induction nozzle like this or this to get a larger droplet size. I think that would be the easiest/cheapest way to solve the problem.

Chapin offers CF Valves in 14.5 psi, 21 psi and 29 psi ratings; however, assuming the Chapin 20V backpack uses a positive displacement (constant volume) pump, I would proceed with caution restricting flow too much since it does not have a bypass. There might be a risk of short cycling whatever pressure switch device they are using. I haven't done it so I can't say for sure, but it might be worth talking to Chapin first to make sure they are good with it. :thumbup:


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## Green (Dec 24, 2017)

I guess I will need to contact Chapin. Hopefully they have advice on this. I'm also hoping to make the liquid in the tank last a little longer, so if there's a safe to do pressure reduction, I think that would be the way to go. The way it sprays when there's about a gallon of liquid left perfect...if it could spray like that all the time, it would be ideal. The mist was bad today...I got some PGR on my lips and it started burning a bit.

Thanks for all the replies so far.


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## gene_stl (Oct 29, 2017)

If there is a screw adjustment on the pressure control switch you could adjust it. It is probably gooed up with a lacquer based thread locking compound which you would have to remove. (the Fimco pump has the screw and the thread locker)If the switch is oriented the same way as on the Fimco you would probably turn the screw to the right (drive it in) to lower the operating pressure and back it out to raise the pressure. You would have to experiment. This would likely void your warranty.
CF valves are a good solution.


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## Ware (Jan 28, 2017)

Reducing pressure may solve your problem, but it's worth noting that lowering the pressure often doesn't change the droplet size enough to reclassify it (see chart below). Nozzle selection trumps pressure changes when controlling droplet size, and droplet size is what drives drift management.

Also pay close attention to wind conditions - I try to spray early in the morning or late in the evening when there is minimal breeze. If I must spray when there is a breeze, I use air induction nozzles to minimize drift. :thumbup:

​


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## adgattoni (Oct 3, 2017)

While we're talking about the Chapin 20v's pressure, here's a somewhat related question (sprayer pressure): does a boom setup affect the pressure of the sprayer? The Chapin 20v is listed at 35-40 PSI. How much pressure reduction would you get with a three nozzle boom? Thinking about getting one, but not sure if I should get new nozzles along with it.


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## g-man (Jun 15, 2017)

Hijacking this thread: what is the difference between the ai and aixr? Ive looked at the charts and descriptions. All I see different is the section view of the part and more course drop size in xr. What am I missing?


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## mtroberts20 (Apr 13, 2018)

The ai nozzles have a recommended pressure range of 30-115 PSI, and the aixr recommended range is from 15-90 PSI.


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## Ware (Jan 28, 2017)

g-man said:


> Hijacking this thread: what is the difference between the ai and aixr? Ive looked at the charts and descriptions. All I see different is the section view of the part and more course drop size in xr. What am I missing?


I think it's a difference in the design pressure of the venturi. AI nozzles have a recommended pressure range of 30-115 PSI. AIXR's and TTI's are rated for 15-90 PSI and 15-100 PSI, respectively.

Material-wise the AIXR's and TTI's are only available in polymer. The AI's have a stainless tip.


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## g-man (Jun 15, 2017)

Given that the chapin working pressure is 30-40, one will mist more than the other? I guessing I will buy both and see what happens. I want better drift management. The XR11004 works great, but the wind pattern in my current house makes it a challenge. I have a TT also but I keep looking for better options.


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## Delmarva Keith (May 12, 2018)

Green said:


> I would like to reduce the pressure on the 20v backpack sprayer. The relatively high default pressure is higher than I prefer. What can I do to reduce it? Different nozzle? Some kind of pressure regulator?


If you're determined to do it, this type of valve will help:
http://www.spraysmarter.com/pres-relief-valve-pp-23120-1-2-pp.html?gclid=EAIaIQobChMI-7nby-bf2wIVVh2BCh10KwV7EAQYASABEgJtGPD_BwE

Get one that covers the pressure range you are aiming for. Run the bypass back into the tank via a bulkhead fitting. Will also help with agitation.

I'd be inclined to go with a nozzle with larger droplet size but you said you are trying to keep spray volume down.


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## Green (Dec 24, 2017)

Delmarva Keith said:


> Green said:
> 
> 
> > I would like to reduce the pressure on the 20v backpack sprayer. The relatively high default pressure is higher than I prefer. What can I do to reduce it? Different nozzle? Some kind of pressure regulator?
> ...


Assuming that would require drilling into the tank, it's not something I think I would actually risk, but thanks for the idea.


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## Green (Dec 24, 2017)

Ware said:


> g-man said:
> 
> 
> > Hijacking this thread: what is the difference between the ai and aixr? Ive looked at the charts and descriptions. All I see different is the section view of the part and more course drop size in xr. What am I missing?
> ...


Are all of what you guys are recommending for nozzles air induction types? I've noticed some herbicides say on the label not to use air induction nozzles with them.


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## Ware (Jan 28, 2017)

Green said:


> Are all of what you guys are recommending for nozzles air induction types? I've noticed some herbicides say on the label not to use air induction nozzles with them.


Air Induction (AI), Air Induction XR (AIXR) and Turbo TeeJet Induction (TTI) are all air induction nozzles.

To increase droplet size without going to an air induction nozzle, I would look at a Turbo TeeJet (TT) nozzle like the TT11004 or TT11002. They offer a larger droplet size than an XR11004, but smaller than an AIXR11004 (air induction).


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## Greenrebellion (Jun 13, 2018)

@Green What herbicides have you seen that mention not to use air induction? I've never seen that before.


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## Mr Efficiency (Jul 4, 2018)

Hi all..

I've got a few of these battery powered Chapin backpack sprayers now and this is the first year using them. I had the same issue with Pressure, too much pressure and no way to regulate it.
I've come up with a kit to install on the line before it goes into the handle of the sprayers that regulates the pressure and it works great. Should work on any backpack sprayer that's Electric that has a 3/8 inch hose. It would even work on the pump backpack sprayers but I've noticed you can regulate the pressure by not pumping it so much so it's not really needed on them.

You can turn the pressure down to completely off, a few dribbles, light spray or Max Pressure, any pressure you want.

You just cut the hose about 3 in before it goes into the handle put on a hose clamp, pop on the hose , tighten the clamps and you're good to go.

I've got a few I'm going to put on eBay, $30 include shipping.


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