Ceres Hardi

Random idea, does it work any better, or for longer, if you leave the lids off the tanks?

Brett.

This is turning out like one of them murder mystery's, we are all on the edge of our seats trying to guess the outcome.

mammoth, nope it isn't slipping on the shaft

Gumpy, key ways all there and gripping

Brett no difference with lids on or off

Louie, it sure is

Im wondering if the pump mechanicals are worn
I wonder if what I assumed was a different stroke is a badly worn pump mechanicals ??

I'll split the casings and have a look

I doubt it is this but I dunno, it is strange how I can get it to run occasionally and run for a long time fine then it just slowly stops

Paul

Paul, I know this is a long shot, but I have had centrifugal pumps build up pressure ok, but when they get too much resistance, they start to create cavitation and lose pressure.

As I said, a long shot as I don't know if this same thing could happen with a diaphragm pump, not having had much to do with them.
Steve.

Hi Mrs
Another random idea. You're splitting the pump anyway
It's been sitting for a while? Maybe bits of hornet nest/rat/bird floating about inside & blocking ports intermittently?
You have all new suction hose I recall.
Sometimes chemicals can de-laminate hose. Been caught with that before
Good luck

Wee Steve
diaphragm pumps are positive displacement, what goes in must come out
a centrifical pump works the opposite 
if a diaphragm pump is capped or blocked it either stalls or breaks, the more head diaphragm pump has the more power is needed to maintain revolutions

A centrifical pump, the higher the head the less power needed to maintain revolutions

Tired iron, the ports I believe are clean

So because it's only 40° I thought why not go out of the A.C. and have a look at the pump

I split my old pump apart, the original hardly used one I replaced with a bigger pump years ago and was some what surprised at it's inside
I am not us using this pump, it's a spare to compare what's what
 
 

The pump I'm using is in much better nic

 

 

Finding not a thing wrong I pulled it apart and then took some photos and put it back together



youtube.com/shorts/S4i-8L34fwk?si=yh37TpuYc2urvEUe

youtube.com/shorts/wXRcSf6OhmM?si=zaIJqxLKzbXQbZbu

the new diaphragms installed

The valves installed 
 
 

There's no sign of any movement on the shaft of the pulley moving

 

The head back on the pump, the regulator in agitate position 
It pumps fine here in this position 
 

The regulator in pump position 
when in this position the red knob sets the pressure on the boom and the rest of the mix is bypassed thru agitation 

 

this actually works but slowly the flow and pressure drop off





The pressure and flow drops off slowly when not on agitate



 

So I have a plan of attack

Ring hardi and see what they say, actually I have a pdf to down load and it talks about leaks in the suction side causing these issues

 

So if I pull the suction side of things out and somehow cap and seal it up to add air pressure to and maybe chuck it all in a stock trough and look for a leak ????

Even a squirty bottle (technical term I'm sure) with soapy water and add some of the Princesses dish washing liquid I might find the leak if it has one 

These really are a crap design, so many joins and places to leak on the suction side

Two joins inside the tank, two more on the tank on the outside, then 6 actually on tyhe pump head 

Then and in hoses and a PVC pipe and things just get harder and harder

Paul

Paul, did you end up measuring the actual operating speed of the pump?

The diaphragm pump on my tray mount sprayer says 550 RPM max.

I am wondering if the pump is maybe spinning a bit too quickly, whether the valves are keeping up, and you are maybe loosing suction and then pressure, because of that??? 
Or because of the very short stroke of the diaphragms, whether excess speed would cause the chem mix to froth up inside the pump as it passes through, and therefore not pump as well???

Probably all unlikely, but i am afraid i am quickly running out of suggestions!

Brett.

 

No Brett not yet, according to the pump it can run at 800 rpm

I have no measuring device that I know of in my tools 

With a 2 inch pulley on the motor and a 4 inch on the pump the motor would have to be spinning at 1600 rpm before I am to quick

Having said that, I can't really tell how quick it's spinning, the motor is at idle 

And I am wondering about whether the valves get sort of bound up

As in if it can't get rid of the liquid then it can't let more in, I don't see how this can happen but I dunno, it could 

I guess I need to make sure there is no leak letting air in, I wonder if the fluid slows then maybe as it's running past it sort works like a venturie type of deal and somehow sucks air in, but I really don't know

Paul