View Full Version : What pressure for spraying
05-11-2002, 09:05 PM
I am new to the spraying business and not sure what types of pressure to use to spray a fertilizer/herbicide mix. The sprayer I purchased is built by turbo technologies has a 5.5hp Honda engine and a Hypro 30 diaphram pump (rated at up to 500psi and 9.5 gal per minute), the gun is a Viton. I want to spray at a rate of 2 gal per minute or per 1000 sq ft, to accomplish this I have to run the system at 100psi. It appears that the other people around here are spraying with about 20 to 30 psi, spray pattern looks coarser like something that would come out of a garden hose end type of sprayer.
05-11-2002, 10:01 PM
All you need to do is do a "bucket check". If you want to spray at 2GPM, simply get a bucket that has a one gallon marker inside. Get a stopwatch and begin spraying at 00 seconds. Stop spraying at 30 seconds. You should have exactly one gallon inside. If not, adjust the regulator up/down until you get the one gallon level. Make sure your strainer is clean each day as the volume will decrease as gunk builds up. Good luck. (Did you get that licence yet?)
05-11-2002, 11:14 PM
Yes I got the license, that was the first step I made. I have already performed the bucket check, and to get the volume per minute that I want the pressure has to be around 100psi, at that pressure the spray droplets seem to be extremely small and tend to have more problem with drift than I believe I would with a coarser spray pattern.
05-12-2002, 09:43 AM
Sounds like you have the wrong type of pump for lawn work. Your pump is probably more appropriate for tree spraying and root feeding. We have a diapraghm pump for our tree sprayer, but the lawn units all use centrifugal pumps.
You could experience serious drift problems at 100 psi, which could lead to significant liablity issues.
I think you should go back to your dealer and rediscuss your needs.
2 gpm seems a little on the light side for lawn apps. I like to use between 3-4. The higher volume is a more dilute mix and therefor is not as potent if it does drift to a non target. This dilution means that you need direct hit to do damage. Much safer
05-12-2002, 10:13 AM
What are you spraying? Many labels will tell you the perferred pressure settings for the type of sprayiing that you are performing. Start there but like was said above, it sounds like you have a tree sprayer with those pressures.
I spray Millennium Ultra, Drive 75 and Dissolve and I use no pressure higher than 40psi. This is out of a boom sprayer, I don't use a gun, small areas get the backpack. Good Luck
05-12-2002, 09:55 PM
The nozzle on the gun is probably the wrong one. Pressure should not matter if you have the right size holes. I am usually at about 60 lbs and I spray at 2GPM. I disagree about the higher volume spray. It is somewhat true that a little mist of it on a rhodo leaf will not curl it like a low volume mix will, but when trying to get control of small-leaf weeds such as veronica and chickweed, a hotter mix will get better results provided you can move the gun fast enough to hit the tissue.
05-12-2002, 10:29 PM
I have the same set up but i use a green garde gun. I use a 4 gal per minute nozzle. I think you need a larger nozzle. I had the same problem before so i went to a larger nozzle. Remember dont up the psi for more volume, use a larger nozzle.
05-12-2002, 11:54 PM
Go to lesco and get their Chem lawn gun with the yellow tip.
You have the worst type of gun to use for lawn apps, it is a mist type.
Then follow the calibration method posted by Matthew above but use 1 full minute to 2 gallons for the yellow tip.
I have a lesco 200 gal with a honda and D30, they are all the same to calabrate.
Now why do you want to spray at 2 gal per a mintue?
I would shoot more for 1.5 gal per 1000 "Blue tip" from Lesco.
200 gallons will treat 100,000 sq/ft and that is not a lot of area
The pump is a great multi purpose pump. Yes lawn apps are done at low volume and CAN be done with the D30 as thousands have done for years.
05-14-2002, 01:37 AM
What size hose are you using? How much hose do you have? What kind of spray pattern do you have out of the nozzle?2gal/1000ft is around 90 gal/ac, which is plenty of water. (And pretty close to what most people put out of a hose.) More water gives you a better chance at coverage.
Low pressue=larger droplets=less drift.
Take some time just to play with the equipment. Get an area, hard top, gravel someplace where you can see where you're hitting. Play with the regulator, play with the settings on the nozzle. practice until you can get real good coverage at the rates you want. Do this with clean water.
No matter how light or heavy your mix, what you spray off-target will show a lot more than what you intend to spray.
Your walking speed has as much to do with how much you're laying down as any other factor (Just as ground speed does in boom spraying) How much volume do you put out at 35-50 psi?
Adjust your walking speed from there. Practice, measure, and it will become habit.
If you are more comfortable thinking in terms of 1000sf blocks, measure out a few500sf blocks to practice in. (Give one time to dry while you work on another)If you want to measure by the acre, measure out an 18ft square. Spray it, getting the coverage you need to get. Time how many seconds it takes to spray it.
Then, spray into a bucket for the same amount of time. The number of ounces in the bucket is the number of gallons you spray per acre. (This used to be on some Dow labels.)
When spraying with a hose, the operator is calibrated as much as the equipment.
If YOU put out 100 g/ac, and you want to apply Confront at 1qt/ac (just to make the math easy) you will add 1 pt to your 50 gal tank. 1/2 pt to your 25 gal tank, 3 qts to your 300 gal tank.
The only important number is the amount of pesticide, or fertiliser, or whatever material it is you are putting down on a particular parcel of ground. You calibrate so you can do that accurately and consitently. If you can deliver coverage with 10 gal of water per acre, that's fine. If you do it with 100, that's fine, too.
05-14-2002, 07:20 PM
Thanks for the information.......i didn't want to toss the gun out and purchase a new one so I tracked down a different supplier and he is sending me a couple of different tips to try......the company that built my sprayer (I had told them that I wanted to be able to spray at a 2 gal per minute rate with about 50 to 60 lbs of pressure) sent it out with a tip that is rated for .75 gal per minute at 100psi.......I found this out from the new supplier that I am now dealing with.....the hose that I am running is 300ft long and 1/2 inch diameter
05-15-2002, 10:36 AM
Here's another consideration--Does your pressure gauge read 100psi when you are not spraying, or when you are? Lots of times it will show your pressure much higher when it's just siting there. some show the same all the time, but not often.
You're actual pressure is what it reads with the nozzle open.
Not much you can't do with that setup. Hope you have the electric take-up reel.
05-16-2002, 08:18 PM
Yes I did get the electric take up reel.......we got the new tips for the gun and it is putting out 2 gal per minute at about 40 psi......the engine is running at less than half throttle.......the gun is putting out a real nice pattern with large drops.......looks like it is finally going to work......thanks to everyone for the input
05-17-2002, 10:24 AM
Good to go! (I've had to roll up and roll out 300 ft by hand too many times.)
Remeber a couple things, when you do your practice squares--Every dry spot in your square is a bull thistle that someone paid you to kill--and you didn't. It's the one they'll step on in their bare feet on the way to the mailbox to send your check. Every wet spot outside the square is Aunt Tilly's prize rosebush, started from a cutting from Queen Victoria's Royal Rose Garden, planted by her own hand, placed in that spot by Aunt Tilly's beloved Grandfather, on his and Grandma Tilly's wedding day.
Feel better about spraying?
Don't forget the spreader-sticker.
05-25-2002, 11:17 AM
Originally posted by Casey
the engine is running at less than half throttle.......the gun is putting out a real nice pattern with large drops
Not supposed to run the engine at that setting.
Engine was desinged to run at full throttle or it will load up with carbon fast.
05-25-2002, 02:44 PM
That's only for 2 cycles.
A little 4 stoke idles at 1800. 3600 full speed.
Any speed on a 4 stoke is no problem. Carbon build up is inconsequencial.
(Can you imagine if your car had to be full throttle all the time?)
05-26-2002, 09:03 PM
Well then, it wont cool it self off under the load of the pump.
BTW a vehical engine varies in rpm constantly, and should have the accelerator mashed to the floor every once in a while.
Running a little 4 stroker at 1800 rpm's constanly for hours is harmful to it under a load.
The block and head wont be able to cool it self off, or disperce of the build up of carbon or excess vapor fuel if run for periods of time under reved.
I suggest reading the owners manual of that engine.
05-30-2002, 03:08 PM
Thanks for the input about the speed of the engine. I was worried about that also, so I took the machine out to the local Honda industrial dealer and they said that it would not cause any problems to run the engine at half throttle.....
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