# Can Someone Help Me With The Northstar Calibration Table



## bmlocal175 (Aug 25, 2020)

I have the 31 gallon sprayer and had a question about the chart
This is an example chart which is pretty much the same as mine but I couldn't find a picture. Using the 1000 sq ft chart you double the gallons because there are 2 nozzles but do you also double the 1000 sq ft also to 2000?

Say you have a product that calls for 4oz in 4 gallons for 1000 sq ft. I want to do 5000 sq ft.

Using the chart above would I mix 20 oz of product with 20 gallons of water and at 35 psi at 1 mph I would be close to my 4 gallons per 1000 sq ft and at the end my tank would be about empty?


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## FlowRider (Apr 7, 2019)

Here is what I would recommend you do. I used this method myself because it was the best way for me to figure out how to spray my yards.

Fill your sprayer up to 20 gallons with just plain water. Use water only.

Then set your sprayer to a set PSI number, and set your towing machine throttle to a set speed (say 5 miles per hour). I use 40 PSI and 4 mph.

Now use your machine and sprayer at full application pressure (40 psi for my sprayer) to first cut in the entire perimeter of your front or back yard, with two passes to cut the yard in. Again, just water.

Then go fill in the middle of your cut in perimeter however you want to, spraying the whole yard. Basically you are just watering with your sprayer. When you are done, look at the tank and see how many gallons you used up. Write that amount down.

Now, go do the same thing in your other yard. Cut it in and fill in the middle. Check again for how many gallons you have used for that, then total it all together. That is how many gallons of water your yard will take at a set rate of pump pressure and machine throttle (speed).

Water is essentially just the "carrier" or liquid you use to deliver whatever chemical your are going to spray.

Then determine how many square feet of area your yards are, combined. This is your total lawn square footage.

Now, most chemicals will provide how much chemical you need to apply when spraying 1000 square feet. This will be by weight (thinks solid material, such as granules, and weight in ounces or grams); or by volume in cups, pints, quarts, usually by ounces (for liquids) - be sure you know if your chemical is solid or liquid, and how many ounces or grams, etc. you need per 1,000 square feet. This is how much of a "dose" you will use to mix with your water (carrier).

To make it simple:

You have a 10,000 square foot yard, total.

Your test shows you used ten gallons of water to cover both yards.

You have liquid fertilizer, and the label says one ounce of liquid per gallon of water.

This means you should only add 10 ounces of liquid fertilizer to ten gallons of water in your tank.

Once you know how many gallons you will spray at a set throttle opening and using a set PSI setting on your pump, and you know your lawn square footage, all you need to adjust for is the "dose" rate.

The secret is to never "overdose" your lawn - don't put in, nor spray down, too much chemical.

But the real secret is to know your equipment - teach yourself how much liquid it will spray down to cover what you want to spray.

Then add only enough of the chemical "dose" to treat your exact square footage, and go spray.

Where people mess up is to put too much chemical into your tank mix.

Hope this helps.


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## FlowRider (Apr 7, 2019)

Paging @bmlocal175

Please see above for my best advice on your question.

Happy Spraying!


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## bmlocal175 (Aug 25, 2020)

Thanks will try it... I guess my confusion is the chart that came with the sprayer is per nozzle. So I wasn't sure if each nozzle sprays 1000 sq ft using the given psi and speed.

Will do some tests.


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## x Wild Bill x (Aug 17, 2018)

@bmlocal175

Yes, the chart you show which is almost the same as shown in their manual for the 31 gallon sprayer is the flow rate per nozzle at the set speed. However, looking at the manual and seeing how these are built, there is a an overlap of the spray pattern in the middle of the sprayer. This is why they say you need to overlap 1/3 of your previous pass - this gives you the second spray on the edge of the previous pass. You also want to do a second perimeter pass with just the outer nozzle on so you get full coverage on the perimeter.

Your math is correct if you wish to put down 4 gallons per M ft^2. I personally go with the 40psi - 4 MPH and 1 gallon / M ft^2 as I have a large lawn and slowing my tractor to 1 MPH would be tough, as it works out 4th gear for me is right on 4 MPH. If you can consistently drive 1 MPH then you should be good. As mentioned above, test and practice with just water.


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## bmlocal175 (Aug 25, 2020)

So I used the 100ft at 1 mph for 68 seconds. The width of the spray is right about 10 ft. so at 100ft of travel that would give me the 1000 sq ft.

I caught the water from both nozzles for 68 seconds at 25 PSI, lowest I could get for some reason. The pressure knob is a little wonky at times. Doesn't adjust down well.

I then measured both buckets and got 1.25 gallons between the two. Which is way less than the chart, should of been closer to 4 gallons which seems like a lot in 68 seconds.

Im going to run it at 40 psi and see what i get


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## bmlocal175 (Aug 25, 2020)

So just ran it at 40psi and got 1.75 gallons total between the 2 buckets for 68 seconds which is 1 mph for 100ft at a 10ft wide spray giving me 1000 sq ft.. Way off from the chart. Am i missing something?

Here is the chart for the 31 gallon sprayer and the label from my weed killer. How in the world can I spray 4 gallons per 1000 sq ft. when at 1 mph and 40 psi I can only get 1.75 gallons? I'm confused. Someone tell me I'm making some math errors somewhere because I'm baffled.


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## bmlocal175 (Aug 25, 2020)

So I just put 8.75 gallons in and did a 5000 sq ft area and pretty much ran out when I finished the area. Did about 1 mph on my lawn tractor.

So is 1.75 gallons per 1000 sq ft my reference point now whenever I need to calculate whatever app I'm putting down?

I figured a 2.2 GPM pump would at least do 2.2 GPM or is that at the pump without hoses, nozzles, etc?


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## FlowRider (Apr 7, 2019)

@bmlocal175

Watching these two videos may help reduce your confusion - don't worry, it confuses almost everyone.


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## bmlocal175 (Aug 25, 2020)

Man oh man. Snow is going to be on the ground before I figure this out. Anyone have a PhD in here?

My yard=28000 sq ft
31 gallon sprayer
40" nozzle spacing
112 oz at 68 seconds which is 1 mph, 40 PSI and 100ft
That equals 112 gallons per acre.

Now what? I'm assuming I need to speed up to get under 31 gallons. 2 mph will get me 56 oz=56 gallons per acre. Still to much. 3 mph will get me 28 gallons per acre. I only have 28000 sq ft. which equals .6427 of an acre. So multiply 28 gallons by .6427 and I get 18 gallons.

18 gallons for my whole yard at 40 psi and 3 mph, is this correct?

And as long as my dose is right with the app I'm using, the per gallon to the app doesn't matter? The weed killer I have (label above) says 4oz per 1000 sq ft. So 28*4 is 112 oz. So put 112 oz in 18 gallons of water, at 3 mph, and 40 psi, i should be good. Right? lol Even though the weed killer says 4 oz per 4 gallons for 1000 sq ft which is really undo able.


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## FlowRider (Apr 7, 2019)

One ounce per gallon treats 250 square feet. That is the application rate you need to adhere to.

You have a 31 gallon tank when it is full. But you have to include the ounces of chemical in the tank.

If you put 30 gallons in the tank, you add 30 ounces to the tank. That one tank will treat 7,500 sq. ft.

To treat your whole yard, you will need about 3.75 tankfuls to finish....

Assuming what you said in your last post is accurate.... 112 ounces in 112 gallons = your sprayed yard.

1 ounce in one gallon treats 250 sq. ft.

4 oz. in 4 gallons treats 1000 sq. ft. per the label....

4 oz. in 4 gallons treats 1000 sq. ft., so to treat 28K sq. ft. means you'll need 112 oz. in 112 gallons water.

Having fun yet?


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## x Wild Bill x (Aug 17, 2018)

When you did your test run of 100ft x 10ft spray, did you make one center pass with both nozzles flowing, get to the end, shut off one nozzle and spray each side of the 10ft to get the double coverage required for the right coverage? If you look at the picture in the manual, and as they sate you need a 1/3 overlap between passes to get the correct coverage. Just driving 100ft with both nozzles on, but no going back over the edges is technically not full coverage of the 1000 sqft. You would have full coverage in the middle where the spray pattern overlaps and only 1/2 coverage on the sides where only once spray pattern sprays.

When you set your pressure are you setting it with the nozzles on and flowing? You need to make sure your pressure is set when the water / product is flowing out of the nozzles.

Most pumps GPM rating is with no restrictions or hoses connected to the outlet, as the pump manufacturer has no clue what the customer or end user will be putting on their pump which will affect flow / pressure.

I think you are trying to flow more liquid than the pump is capable of providing. The pump is rated for 2.2 gpm, so there is no way you will get 4 gallons of water in 68 seconds... I'm thinking Northstar's table is based on the flow rate of the nozzles that are provided with the sprayer and do not take into account the flow the pump can provide.

Just my thoughts. I hope you figure it out. I have very good, consistent, repeatable results with my 31 gallon sprayer putting down 1 gallon per 1M ft^2 running at 40psi dynamic pressure and a 4mph ground speed, spraying the perimeter a second time with just one nozzle on to get full coverage.


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## bmlocal175 (Aug 25, 2020)

x Wild Bill x said:


> When you did your test run of 100ft x 10ft spray, did you make one center pass with both nozzles flowing, get to the end, shut off one nozzle and spray each side of the 10ft to get the double coverage required for the right coverage? If you look at the picture in the manual, and as they sate you need a 1/3 overlap between passes to get the correct coverage. Just driving 100ft with both nozzles on, but no going back over the edges is technically not full coverage of the 1000 sqft. You would have full coverage in the middle where the spray pattern overlaps and only 1/2 coverage on the sides where only once spray pattern sprays.
> 
> When you set your pressure are you setting it with the nozzles on and flowing? You need to make sure your pressure is set when the water / product is flowing out of the nozzles.
> 
> ...


So the overlap you are counting that water into the formula?

I ran the pump yesterday at 30 PSI and timed how long to get 1/2 gallon from each nozzle. It was about 45 seconds. I then set my lawn tractor on cruise and made sure I was around 45 seconds for the 100ft. So I should of been putting down 1 gallon of water per 100ft. I overlapped all passes except the outer ones which I will in the future.

Does this sound correct? My front lawn is 10000 sq ft, so I put 10 gallons of water in and ran out pretty much right where I needed to. I guess if I needed to do the outsides again I wouldn't of had enough.


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## x Wild Bill x (Aug 17, 2018)

Yes, you account for that perimeter pass into your total solution.

If you imagine looking at the back of your sprayer, the two nozzles overlap in the middle and each are flowing 1/2 gallon in 45 seconds. This gives you a total of 1 gallon in 45 seconds where both nozzles are spraying. However, on the outer edges where only one nozzle is spraying it only receives 1/2 gallon in 45 seconds and that's why you should do a second perimeter pass with only one nozzle spraying on the outer most edge. Now, if you don't care about overspray and drove close to the edge of your lawn with your initial perimeter pass then you don't need to do a second perimeter pass with only once nozzle spraying as you already applied the appropriate rate to the perimeter.

It is definitely a trick to walk the line between complete coverage, correct speed and overlapping pattern. The more you spray the better your technique will become and the more comfortable you will be with your equipment. I always err on the side of caution depending on what I am spraying as I would rather be a little light on coverage than accidentally double dose and cause turf damage or overspray damage.


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