Need help with a sprayer

[coosa]

I wonder if any of you good folks could help me with a problem I am having with a sprayer? It was made by Wallberg Sprayer of NC and has never worked right. I bought it new 3 years ago and am about ready to give up on it.

This a sprayer that utilizes a 55 gallon drum for the tank. A line attaches to a fitting that comes out of the bottom of the tank and leads to the pump that attaches to the pto. A metal frame holds the tank and includes the 3 point hitch. The line from the pump to the 10' boom has a pressure gauge, a cutoff valve, and a smaller line that carries excess fluid back to the tank. Increasing the pressure will decrease the amount of fluid that returns to the tank. I hope I have described it well enough so that you can understand the type of sprayer that it is.

The problem is that it will not maintain the pressure at a consistent level. I can set it up at 50 lbs of pressure and it will work great for about half a tank; then the pressure may gradually drop to 25 lbs. Sometimes it will drop to almost nothing. The lower the tank gets, the more the pressure drops. It is impossible to get a uniform spray with this thing. I use it only 2 or 3 times a year, but it gives me the same problem every time.

I suspect that it might be that I don't have an airtight seal between the tank and the pump, but I have tightened everything as much as I possibly can. It seems like that every time I use it, I think I finally have it fixed, and then it starts losing pressure again.

I am using it to spray herbicides, both pre-emerge and post-emerge. I have sprayed Prowl, Treflan, 2,4-DB, Poast, and Broadstrike. I have the same problem no matter what herbicide I am using.

I am thinking of junking this thing and buying an ATV sprayer, but I thought somebody here might could give me an idea to try. Many thanks for any ideas.

Steve

 

[beenthere]

Welcome to the forum.

What size lines do you have between the tank and the pump?

What kind of 'pressure' adjustment do you have at the valve that returns excess fluid back to the tank?

Seems either the line is too small between the tank and the pump, or the adjuster valve is faulty.

Hopefully it is not the roller pump that is failing.

 

[Indydirtfarmer]

Is there a strainer at the tank's outlet? (before the pump) How about after the pump, before the regulator? More often than not, sprayer pressure problems are related to strainers stopping up.

Also, the return line (from the regulator, to the tank) is functioning as an agitator. Sometimes that return line needs to be "throttled down" (restricted somewhat) to maintain pressure.

Finally, check function of that regulator....

Good luck!
Bill

 

[coosa]

Thanks for the quick replies. Beenthere, I think it is a 1" line, but the sprayer is at the farm and 80 miles away so I can't measure to be sure. The only pressure adjustment is a very cheap pressure regulator. You simply turn it in to increase the pressure. It may well be the regulator, but it seems strange that it will work perfectly with a full tank and then drop off as the tank empties. And yes, I hope it is not the pump, but I have thought of the possibility that the pump was bad right out of the box.

Indydirtfarmer, there is a strainer on the line where it comes out of the tank, but I don't think there is one on the other side of the pump. Maybe that is the problem.

You said:

"Also, the return line (from the regulator, to the tank) is functioning as an agitator. Sometimes that return line needs to be "throttled down" (restricted somewhat) to maintain pressure.

Finally, check function of that regulator.... "

The return line is restricted by the regulator - that is the way it controls the pressure. If the regulator is wide open, most of the flow will simply return to the tank. I can close the cutoff and all of the flow will return to the tank.

I'm not sure how to go about checking the function of the regulator. I thought about just replacing it. Even when it seems to be working, the needle is constantly in motion. If I set it for 50 lbs, it is bouncing from 40-60 and 50 is just an average. Should it be steadily on 50?

Thanks again for the help.

Steve

 

[beenthere]

What happens when the pressure drops, and you tighten down the regulator valve? Does the pressure come back up to 50 lbs?

I'm thinking (based on your comment that the pressure bounces from 40-60), that the regulator may be undersized for the pressure/volume combination your pump is putting out. Maybe a check of new regulators and related specs can help determine if that is a possibility.

Also, is the pump below the bottom of the tank such that there is always gravity flow to the pump, and it isn't drawing fluid up to the pump? Also, that the line is a full 1" inside diameter, and not the garden hose type fittings that would reduce the volume at the connections.

Just thinking outloud here. Hope you track it down.

 

[Indydirtfarmer]

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"Also, the return line (from the regulator, to the tank) is functioning as an agitator. Sometimes that return line needs to be "throttled down" (restricted somewhat) to maintain pressure.

Finally, check function of that regulator.... "

The return line is restricted by the regulator - that is the way it controls the pressure. If the regulator is wide open, most of the flow will simply return to the tank. I can close the cutoff and all of the flow will return to the tank.


Steve
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I'm referring to where the line returns to the holding tank FROM the regulator. As you decrease pressure with the regulator, excess pressure is "vented" to the tank. THAT LINE is the return line. Where it empties back in to the tank is where I'm saying it MIGHT need to be restricted/"throttled down" somewhat. Where it empties into the tank also keeps the tank mix agitated. Most sprayers have an "orfice" on the end of that return line. It has various cone-shaped "restrictors" that are used to throttle down the flow returning to the tank.

 

[coosa]

>>>>What happens when the pressure drops, and you tighten down the regulator valve? Does the pressure come back up to 50 lbs?<<<<<

It will come back up for a while, but it usually continues to drop and I have to stop and tighten it down again. Sometimes it won't be enough even with it tightened all the way.

>>>>Also, is the pump below the bottom of the tank such that there is always gravity flow to the pump, and it isn't drawing fluid up to the pump?<<<<<<

I keep the tank high enough that it is always above the pump. I have called the company that made it and they claim to have never had this problem with one of their sprayers. You guys have already given me more ideas than they did. Thanks again.

 

[coosa]

Indy - I understand what you are saying now. There is nothing on the end of the return line. The return line is a 1/4" line and they simply drilled a hole in the top of the tank and pushed the line in far enough to make it stay there. It doesn't provide a lot of agitation. Sounds like I've got a poorly designed sprayer, doesn't it?

Thanks for your help.

 

[Indydirtfarmer]

A few flaws, but nothing that can't be fixed.... Usually, that return line enters the bottom of the tank, through a bulkhead fitting. By releasing the "overflow" of pressure into standing tankmox, it keeps that mix agitated. I'm guessing by releasing it at the top of the tank, there'd be a problem with foaming too.

I'm still leaning towards a restricted strainer. (OR... wrong size (microns) mesh in strainer...Tee-Jet recommends specific strainers for specific spray tips.)

 

[jeffinsgf]

I have a very similar set-up and haven't had the problem of dropping pressure. I thought I would throw out a few brainstorming ideas.

Since no one else has mentioned it, It is very important that you maintain a PTO RPM of 540. You will have to adjust your gearing to give you the proper ground speed for the engine RPM necessary to keep the PTO turning at 540. I suspect this since your pressure drops as the tank empties out and gravity isn't helping the pump as much as when the tank is full.

As mentioned earlier, if you haven't, check the strainer for sediment and debris.

My needle bounces like crazy, too. So do the electrics, so don't run out and buy one of them to solve that problem. If you can keep it consistent to plus or minus 10 pounds, you'll get a consistent spray.

Check your roller pump, too. Is it 4, 6, or 8 roller? If it is a 4, you may be asking more from it than it can deliver. An 8 is probably overkill for herbicide application. A 6 is the middle ground and what I am using.