Cavitation

C

Chris Tharpe

New member
I have inherited a few pieces of equipment and they all have the same issues in common. They are all cavitating. Each setup has a ts1511 and t991 on it and both pumps are plumbed to seperate tanks so we cannot link it to a bulkhead issue.

Ts1511- plumbed to water tank, unloader bypassed back to tank. This pump I have re-packed it, swapped check-valves out of another known running pump with no issues. I inspected the ceramics and they are all good. I have re-plumbed the inlet with new fittings to ensure there is no issues there, I have changed the inlet hose, checked the opposite inlet for leaks and all is good there.


Am I missing something here? No milky oil before the packing change but wanted to make sure I didn't have any issues in the future.
 
Got a thermal relief valve on the pump?
 
If there's no thermal relief to suck air, as Russ suggested..
go back to the pump..
When you had the head off.. did you check for in & out play on the rods ?

Did you check for erosion under the checkValves ?
Maybe somebody got the bright idea of descaling both systems with muriatic acid and eroded the heads

Maybe somebody got the bright idea of replacing the O-rings under the check valve, an used the wrong size on all.
..and always use Viton under the valves.. stiffer is better.

What is the pulley ratio ? .. spinning too fast is problematic.
 
I will check into these other ideas when I see it this week. I am unsure on the ratio's of the pulleys and there are no relief valves on them, I changed out the valves however I don't recollect seeing any o-rings under the valves at all now that we mention it on the 1511. I will check on this and go from there. I am thinking of canning the pumps and changing them over to 5.5 XWA's that I have sitting around
 
Chris Tharpe said:
I will check into these other ideas when I see it this week. I am unsure on the ratio's of the pulleys and there are no relief valves on them, I changed out the valves however I don't recollect seeing any o-rings under the valves at all now that we mention it on the 1511. I will check on this and go from there. I am thinking of canning the pumps and changing them over to 5.5 XWA's that I have sitting around
Click to expand...

If the unloader is bypassing to a tank, , is the discharge blasting right at the bulkhead drain fitting?
 
This is something I am testing on this rig and a couple of others. I have it on a loop bypass that goes into the tank and comes back out of the tank to keep the water in the bypass hose cooler when someone lets off the trigger. Its a single piece of hose that I just fed into a hole in the tank and allow it to coil up in the bottom of the tank, and it comes back out another hole in the tank with no connection being made other than the unloader and back into the inlet side of the pump. We run soap through the pump so this allows us to use trigger guns and still not flood our water tanks with soap.
 
So you are running a long bypass hose, this is your problem. Cut the hose down to its smallest comfortable size and see if the problem continues.

Why not switch from low pressure soap to high pressure soap? Do that switch and you can bypass to the tank and your problem solved.
 
the long bypass hose can ONLY be a problem IF there's trapped air in it..
This is one of the reasons we use clear nylon-braid hose for low-pressure and suction lines..
TROUBLESHOOTING in a HURRY. You have to search for what you can't see.

And.. a good reason to bypass to tank.. troubleshooting the unloader takes a few seconds..
..its either bypassing or not.

Solve the soap problem with a soap solenoid.
 
Benjamin said:
So you are running a long bypass hose, this is your problem. Cut the hose down to its smallest comfortable size and see if the problem continues.

Why not switch from low pressure soap to high pressure soap? Do that switch and you can bypass to the tank and your problem solved.
Click to expand...


we are running soap under pressure hence the long bypass hose that doesn't actually bypass into a tank rather back into the pump.
 
Sirocco Jerry said:
the long bypass hose can ONLY be a problem IF there's trapped air in it..
This is one of the reasons we use clear nylon-braid hose for low-pressure and suction lines..
TROUBLESHOOTING in a HURRY. You have to search for what you can't see.

And.. a good reason to bypass to tank.. troubleshooting the unloader takes a few seconds..
..its either bypassing or not.

Solve the soap problem with a soap solenoid.
Click to expand...

I changed out the unloader itself as well during this whole ordeal to see if that was an issue as well and nothing changed. I see small bubbles in the bypass hose and have done what I thought was a good job of getting all the air out of the line before putting it back on the hose barb. To verify this I even took the bypass hose back off of the hose barb going back into the pump, covered that hose barb and still had a cavitation issue.

As far as solenoids and remote systems etc... Sure they are good for owner op's but when your trying to run rigs 400 miles apart and have little valves on units that do go bad it just means you will be driving a lot to fix equipment. I am one who believes simpler is better. Traditionally we don't even run unloaders on these units because that's just something else to fail in the field and cause problems. Each unit has a spare machine on it just in case something goes wrong and one is not working there is a backup to get the work completed.
 
Chris Tharpe said:
As far as solenoids and remote systems etc...
Sure they are good for owner op's but when your trying to run rigs 400 miles apart and have little valves on units that do go bad it just means you will be driving a lot to fix equipment. I am one who believes simpler is better.
Traditionally we don't even run unloaders on these units because that's just something else to fail in the field and cause problems. Each unit has a spare machine on it just in case something goes wrong and one is not working there is a backup to get the work completed.
Click to expand...

Relays and solenoids installed correctly are very reliable.. It is true that most people won't install them correctly.
..and using components that are readily available, keeps 'em serviceable.

On your unloader comment..
I hope that you have a Regulating-Relief valve.. to control pressure more accurately than a wimpy "pop-off" relief,
.. in an emergency, like a suddenly plugged nozzle.
LOTs of new guys are in here with NO safety-relief on their HomeClub quality pressure washers.
We have to be thorough in teaching these guys.
..Their wimpy single-wire hoses are easily blown.

Back to troubleshooting your mystery machine issue..
If you haven't done it yet..
Pressurize the inlet-side of the pump to check for leaks.
..Small problems become big ones in high-performance equipment.
 
Gonna ask a dumb question here. How big is the pipework supplying the pump from the tank??
If the supply pipework is to small the pump will starve and create cavitation. I have a 3000psi unit that draws 22 litres per minute and from the supply tank there is an 1 1/4" supply. Naturally the supply steps down to match the pump inlet but it is done right at the pump to minimise the throttling effect of the step down fittings. With a flooded suction and no pressure on the supply side of the pump the more water you can offer the pump the better.
 
WASH-IT H.B. said:
Gonna ask a dumb question here. How big is the pipework supplying the pump from the tank??
If the supply pipework is to small the pump will starve and create cavitation. I have a 3000psi unit that draws 22 litres per minute and from the supply tank there is an 1 1/4" supply. Naturally the supply steps down to match the pump inlet but it is done right at the pump to minimise the throttling effect of the step down fittings. With a flooded suction and no pressure on the supply side of the pump the more water you can offer the pump the better.
Click to expand...

Good advice to most people and situations. The only thing that changes is when someone is trying to draw soap into a pump as well as water. If you have a "flooded" inlet then the pump doesn't create enough suction and pull from the other inlet to draw soap into the pump. We actually have to go the other way on 5gpm pumps use 1/2 ID hose then push a piece of 3/8 hose inside that 1/2 hose at the very end nearest the pump to create the necessary suction to make the pump draw soap through the other inlet.
 
pump manufacturers love when you starve a pump with flow restrictors.. they sell parts.
I have found many ways to feed chemicals without eating seals.

BTW.. the XWA's are rated at 1750rpm .. they will act different than your 1450rpm pumps.. at drawing soaps.
 
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