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sandy creek
12-15-2010, 08:43 PM
just got a lesco skid sprayer and spent a little time this evening learning how to work it. Going to calibrate it tomorrow but put a 4 gpm nozzle on it and adjusted the pressure till I got it to go shoot 4 gpm, then put on a 2 gpm nozzle. Also got 4 gpm. All of this is pretty new to me, am I doing something wrong? Also to get the 4 gpm I had to run the pressure to about 180 psi. The manual said to adjust to 100 psi. Any and all advice/help is welcome.

RigglePLC
12-15-2010, 10:29 PM
We have a pump expert on here. He will chime in I am sure. Meanwhile--the nozzle does not control the amount you spray--rather it is called a 4 gpm nozzle because at that flow rate the pattern will be consistent and uniform. 3/8 or 1/2 inch hose? How long? Friction loss in a long hose is major. I am thinking 180 pounds is excess. Very hard on the hose and pump. Why do you need 4 gpm? 2 gpm is better for weed control and your tank can go twice as far between fillups.

But perhaps you plan to mix fertilizer and herbicide like I used to do. 180 pounds is uncontrollable and will probably cause a lot of fertilizer burns. If you can use fertilizer at 3 gals per minute, that should work about right. Reduce the fert concentration in hot weather, or the grass will be toast.

grass4gas
12-15-2010, 10:33 PM
I do a little bit of liquid lawn apps using a lesco 200 gal sprayer as well.

I adjust the pressure to calibrate the nozzle size I use. I write them down and keep em in the truck for reference...no guessing after that.

sandy creek
12-15-2010, 11:57 PM
I've got 200 ft. of 3/8" hose. Backed the pressure down to 100psi and put on the 2 gpm nozzle (yellow). Seems a lot more controllable. With the trigger down I've got about 45-50psi on my gauge.

sandy creek
12-15-2010, 11:59 PM
Also running the engine at about half throttle....if that makes any difference. Thanks for the replies so far

KES
12-16-2010, 12:13 AM
The pressure will drop when you press the trigger. Just make sure you set the engine at a rpm and leave it alone and do all the adjustments with the regulator. Doing this will make sure you are always set up at 2 gpm. I run my engine at half throttle all the time. Make sure to do a bucket check every week.

Hope this helps.

grassman177
12-16-2010, 01:38 AM
once you get the gpm right, then you have to get your walking speed down to get that 2 gal sprayed over 1000sqft.

if you find you dont like the speed at which you have to walk to get that, change the pressure up or down to match the speed you like etc.

a personal gps speedo cheapy would be good for this, i did not learn that way though.

also, if you mow too, stripes can be very helpful in knowing where you have sprayed and not, i love to follow stripes. i used to have a diff pace for spraying 2gal per K, one that was a bit faster for following 48in stripes, and one for 60in stripes.

i sprayed two stripes at a time walking down the middle of them.

Pumptecguy
12-16-2010, 11:20 AM
sandy creek:

The nozzle you have is based upon you already having determined you have 4 gpm. It cannot be used as a diagnostic tool to achieve 4 gpm.

A way to calibrate is to use a ball valve on hose end and close off until your desired gun pressure is reached. Then, measure what that flow is with the bucket, scale and stop watch method. Adjust the regulator back at the pump until you can match the desired flow and pressure at the end of the hose (gun). (you will need a pressure gauge for the end of the hose)

Do the same for the 2 gpm nozzle.

An alternative to this is to buy a Spraying Systems '40 and '20 nozzle and calibrate this way. The '40 nozzle will allow 4 gpm at 40 psi and the '20 will allow 2 gpm at 40 psi. These pressures are 22.5% higher at 60 psi.

The pump/regulator pressure will be higher to overcome the line loss from running all the flow through all that hose.

I hope this helps. There is helpful information related to this in our Sponsor section.

cgaengineer
12-16-2010, 11:47 AM
Also running the engine at about half throttle....if that makes any difference. Thanks for the replies so far

Unless you have a tach, running the engine at what you think is half throttle and doing it the same each time will be unlikely. Flip the throttle till it stops.
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RigglePLC
12-16-2010, 12:22 PM
3/8 hose is not really suitable for over 3 gal per min. When the speed of flow through the hose is too high, friction losses become huge.
If you walk at 3 mph(too fast),--and spray 7 feet wide--you will cover 1800 sqft per minute.

At 1 mph you will walk 88 feet per minute. At 7 feet wide that is 616 sqft per minute. Too slow. I suggest 2 mph, thereby covering 1232 sqft per minute, (at 7 feet wide). You then need 2.464 gal per minute flow rate. I would estimate you need about 120 lbs pressure, you have to find this by trial and error. But maybe Pumptec can calculate this for you. You are using the Hypro three diaphragm pump, right? Keep motor speed constant. If you install a cut-out switch to stop the motor--you can leave the throttle set at the same place all season, (I did this).

cgaengineer
12-16-2010, 12:36 PM
I run a Hypro D252. I have calibrated my sprayer with a bucket to pump 2gpm. Based on my 8' spray swath and my walking speed, I am putting out almost exactly 1 gal per 1000.

In front of my house in my street I have 2 8' wide paths 62.5 feet long painted in the street next to each other that I use to check myself whenever I change anything and for no particular reason from time to time. This keeps my application rates in check and I can see if I am still applying/walking at the same speeds as before. I cover this 1000 sq ft area in 30 seconds. Maybe too fast for some, but its a comfortable pace for me and I am able to duplicate it over and over so I am consistant in my application.
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CHARLES CUE
12-16-2010, 12:40 PM
I guess i do this a little different.

To me the most important part is to know what you spray per th sq ft. Not how many GPM.

I mark out a th sq ft 20 by 50 than spray it with water and time how long it takes to spray it. Than put put your lawn gun in a bucket and spray for that amount of time and measure how much water came out. Thats how much you spray per th sq ft.

Just remember either the first or last pass you make will be 5 ft out side your box you measured for your th sq ft that is for over lap.

Charles Cue

cgaengineer
12-16-2010, 12:48 PM
I guess i do this a little different.

To me the most important part is to know what you spray per th sq ft. Not how many GPM.

I mark out a th sq ft 20 by 50 than spray it with water and time how long it takes to spray it. Than put put your lawn gun in a bucket and spray for that amount of time and measure how much water came out. Thats how much you spray per th sq ft.

Just remember either the first or last pass you make will be 5 ft out side your box you measured for your th sq ft that is for over lap.

Charles Cue

More than one way to skin a cat! Doesn't matter how you do it actually...

I just calibrate with a bucket first to the GPM specified for my nozzle (2 gpm for 2 gpm nozzle and 3 gpm for a 3gpm nozzle)
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CHARLES CUE
12-16-2010, 01:06 PM
More than one way to skin a cat! Doesn't matter how you do it actually...

I just calibrate with a bucket first to the GPM specified for my nozzle (2 gpm for 2 gpm nozzle and 3 gpm for a 3gpm nozzle)
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Your right there. Doesnt matter what ever works for you is al right with me.

Charles Cue

IRS
12-16-2010, 05:35 PM
How do you hold spray gun? out at a 90 degree angle or tilted toward ground? wrist action or arm motion, do you ever let off trigger? has any one ever
seen video showing proper way to use chem-lawn gun?

cgaengineer
12-16-2010, 05:38 PM
I use mine at a 90° angle. I use the Green Lesco gun which can bethrottled down for smaller areas in which I will use the gun outside of the 90° angle and pointed more towards ground. The angle really doesn't matter as long as you use it the same way you calibrate it at.
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