Scratching my head on a new Sprayer/Roller pump

[NC Plotter]

I bought a 55 gallon Fimco 3-pt. boom sprayer to use with my 33 HP Kubota. The sprayer retailer recommended a specific pump and coupler - the Delavan 6900c. So, I ordered all 3 and proceeded to assemble the setup. There was a few kinks to work out, including missing parts from Fimco, lack of a torque arm, and a return line that was engineered too small for the sprayer to function correctly, but I got all of that straightened out.

The problem is the pump is vibrating, rattling, and causing a lot of variability in the pressure on the sprayer. For example, the sprayer lists ~30 PSI as the best pressure for optimum spraying, but when I set it about that pressure, the gauge needle is vibrating from 20-40+PSI. There's no way to begin to dial in or calibrate the sprayer when the pressure is bouncing all over. The rear PTO RPM is 540 max, but this is running it just over 300. If I bump it up to over 500, it just vibrates even worse. I have checked everything imaginable with the sprayer, and even troubleshooted on the phone with a Delavan rep, with no success. So, they sent me a new pump. The new pump does the same thing!

It is pumping fine, in the sense that I have plenty of pressure, but the pressure is varying wildly. I have checked the tank, the strainer, all hoses, bypass valve, etc. I'm getting good return to the tank, the coupler and PTO shaft seem to be on tight and are turning smoothly. But it sounds like a handful of bolts turning around in a washing machine inside that pump.

Has anyone had this problem before? Is there anything else I can try?

 

[HAPPYNC]

I'm not very knowledgeable about sprayers and need to build one myself but do you think a liquid filled gauge might solve your problem. A gauge vibrating like that is just going to wear out prematurely on top of not being able to dial it in. Another thing would possibly be to get a gauge with a lower range....say 0-60 psi versus 0-100 psi. That way your 30-40 range will be spread further apart than a dial with a higher range.

Just a thought.

 

[aczlan]

Does the output from the boom/wand vary, or is it about the same all the time (ie: pressure/flow varies with RPMs)?

Aaron Z

 

[Smallplot]

Do you have the pump chained so it is not constantly moving with the torque of the pto shaft? It should not sound like you described.

A 6 roller pump is pretty big for a 55 gal sprayer, this pump can move over 19 gal per minute and reach 300PSI. Maybe a 4 roller pump would be a better fit, you have not mentioned if you are using a boom or boomless and what type of tips, which would be the consideration factor for size of pump. What type of pressure regulator are you using?

This is just a guess on my part but the jumping around tells me there may be a problem with not having a bypass line with a large enough diameter to handle the necessary volume of bypassed solution. Also make sure none of your hoses are kinking during normal operation and any in-line filter is clean and not causing an obstruction. Did both pumps have the same sound during operation?

 

[stuckmotor]

The intake line isn't repeatedly collapsing then springing back out, is it?

 

[wcampbell47]

Sounds similar to a problem I have if the intake line is obstructed either by a dirty filter or a kinked hose. My sprayer has a valve on the bottom by the filter that allows me to shut off flow from the tank. I think you would have the issue described if that valve were not fully open or obstructed. Does fluid free flow from the tank on the side that goes to the pump "in".

 

[wngsprd]

Post a picture of your pump connected to your tractor PTO so we can help determine if the torque arm is set up correctly.

I have what sounds like the same basic sprayer (11ft boom), and a Hypro 6 roller pump and have had no problems for the 9 or 10 years I've used it, other than a small leak at the gauge.

 

[orangeandgreen]

Double check for a kinked/ obstructed inlet hose to the pump. I could hear cavitation at times with mine and found that the black inlet hose would kink when the 3 point was lifted beyond a certain point. I replaced my inlet hose with a more rigid hose like this.
1 Epdm Poly Helix Suction Hose
No more problems for me. This hose is sold by the foot an most "farm stores" I have been in.

 

[Rocky Hoffler]

AG SPRAY IN DOTHAN AL. HAS AROLLER PUMP WITH A SPLINE ADAPTER FOR LESS THAN 150 BUCKS ITS WHAT I USE ON MY SPRAYER I THINK ITS CALLED A HYPRO PUMP.

 

[NC Plotter]

I think you guys are on the right track with insufficient flow on the intake line. I spoke with folks from both the pump and sprayer manufacturers, and have decided it must be insufficient flow for some reason. What's puzzling is that this is a combo they have been selling for years, with no problems.

I have double and triple checked everything. I had a little bit of extra slack causing an "S" turn in the intake hose, so I cut it off to try to straighten that hose out a bit. After looking at the system, it seemed like the tightest constriction from the tank to the pump is when it goes through the ball valve in the cutoff. It is a 3/4" line, but the ID of the ball valve is probably 3/8". Fimco sent me a new valve with a larger ID on the ball, and I am going to replace with that one and see if it works better.