Foamy frothy coolant..........what's going on with the pump?

Coolant kept foamin' over......... Skimmed it(extra). Pumped it out into a 55 gllon drum and let it sit over the weekend and skimmed it aggin'.............Added a bit of the anti-foam schtuff..........Still made suds.............So I swapped it out...................But the coolant wasn't all that old? Pumped out the old stuff, cleaned the tank, topped 'er off with the new stuff. Turn my back on it and it's foamin' aggin'..................but.......the pump sounds "odd"? Like she's suckin air? What's goin on? No frills pump other other than it's an upgrade from the standard PSI pump. This one is 145PSI or so. Pull er apart? Never pulled one of these apart? Anything to look for that might be the culprit?




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Just to knock out the basics- did you have adequate sump level at all times? I've been known to run a sump real low by accidentally letting chips clog the returns and causing coolant to stack in the enclosure.

Nothing real high tech going on inside a coolant pump so I wouldn't hesitate to pop it open.

If it's a highish pressure (which it is) and the inlet is restricted it could cause cavitation

Cole2534 said:

Just to knock out the basics- did you have adequate sump level at all times? I've been known to run a sump real low by accidentally letting chips clog the returns and causing coolant to stack in the enclosure.

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It's all clean and topped off......................

Pulled the pump apart...........a few small stringy chips hangin onto the impellers.................got er' cleaned up, but looks like some kind of sealant between the cast iron plates? Or it might just be crusty schmoo? Is there some thing between the plates for sealing? Or do they just stack and seal on their own?

There may be a ceramic shaft seal behind the impeller that is allowing an air leak.

230C? (noticed the blue tint) I'm having the same foaming issues! Are you using RO water? (I am)

wheelieking71 said:

230C? (noticed the blue tint) I'm having the same foaming issues! Are you using RO water? (I am)

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S685...........it's blue cuz it's in a blue tray.

I think she's sucking air from the top seal...................I have the standard pump that I can throw back on.

It's a A-Ryung pump made in Korea.........o'course it is discontinued and replaced by a different model. I'll have to see if I can track down a new seal ..............Ellioson needs $2k for a new one.............

Don't overpay for a higher-pressure coolant pump.

These Taiwanese Walrus pumps are kickass. You might have to make a doughnut spacer ring if a pump has more stages (and thus longer from mounting flange to bottom), but surely you could find somebody who has a machine shop...?

(Oh, one thing to think about: if the intake of your pump is on the bottom (and most are), you can't have the bottom of the pump setting too close to the bottom of the tank. The pump can cavitate the thin space before rushing coolant has time to fill the space!

On edit: pay more attention to amp draw at 60hz 220-240 than stated "pressure". This Walrus pump is 7.6 amps draw at 240/60. I've got a couple, and they blow some serious coolant...no idea of actual pressure, but it's plenty for anything but maybe deep, deep small-hole drilling.

They only state this pump as 80 psi, but that's at maximum flow. We never get maximum flow on most cnc machines because the coolant passages and ports are so small! So at our flow rates, I'm betting this pump is 3 or 4 times 80 psi....

What is the amp draw on your pump? That's primarily what you want to compare among multi-stage centrifugal pumps, as they are all constructed basically the same.

TPHK4T6-6 Walrus Coolant Pump 2HP 80PSI 35GPM | eBay

ToolCat

It's unlikely sucking air through the top seal as that part of the pump is under positive pressure. The shaft seal stops the fluid getting up in to the motor.
Agree with previous answers about cavitation so make sure you have a big enough gap under the pump.
You said you are using RO water. We use DI water but never for an initial fill. ONLY for top off. There needs to be some level of dissolved solids in the sump otherwise foaming is going to happen. Using RO for top off prevents the dissolved solids from steadily accumulating as the water evaporates off.

Did you recently open a new batch/drum of coolant?

I had a lot of foaming issues when I set up my new lynx that has a 145psi pump like that as well. Couldn't even run for 1 minute it was foaming harder than a CNN reporter at a Trump rally.
Tried defoamer, no real change. Modified my coolant nozzles to get less air into it, no big difference. Tried another type of coolant from same manufacturer, tiny bit better but still too much foam and other things I didn't like about that coolant.
Finally changed coolant brand, running Fusch 7830C since, problem solved enough to be able to run and haven't had it overflow once yet. There's a couple things that could be better about it, but so far its still the best coolant I've ever used. Maybe someday I'll try to find something else again but changing coolants is always a risk and mess if it isn't better than the last one.


Also double check that nothing's clogging the coolant drain holes as it returns to the tank, and that the tank isn't half full of chips if you do any stuff that makes tine fines that could get through the holes/filter and settle in the tank.

cnctoolcat said:

We never get maximum flow on most cnc machines because the coolant passages and ports are so small! So at our flow rates, I'm betting this pump is 3 or 4 times 80 psi....

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As the nameplate reads, 82meters of head (117psi) at 60Hz is maximum pressure at zero flow. You're looking at the -6 curve.

Vertical Multistage Centrifugal Pump - TPHK4T | Walrus Pump

Threw the standard pump on 'er and no foam...............no even a trace.

The big pump had an odd sound too.............no quite a whistle, but definitely suckin' wind.............prolly from the top seal where the motor shaft enters the pump. Like I said, this pump model has been discontinued, but I'm gonna take her apart and track down a seal..............in the mean time I'll run the standard pump and maybe pick up one that The Cat Man suggested...................