[kunalv]

I've connected an eductor to the coolant pump in my machine. This eductor sucks the leaked cutting fluid from a tray underneath the machine I.e coolant passes through the venturi(let's call it motive) and returns to the tank and in this process a vacuum is developed which is used to suck up the oil from the tray which travels with the motive and enters my tank.

Now the problem I'm facing here is once all the leakage oil has been sucked up the device keeps sucking air which is then transferred into the coolant sump thereby causing a lot of foam.

How can I prevent air from entering the tank? I cannot use any timers or solenoids to turn off the system. Need a simple mechanical suggestion please. Can't add any Calcium or any other defoamer either.

We have tried to keep the return pipe submerged under the coolant level and kept it over the coolant level to see if either helped, but both situations created foam. Concentration & water softness is high, and the client is adamant on maintaining the existing parameters due to the surface finish requirements.

Please see a schematic of how the system is working right now : https://i.imgur.com/nZbOKG1l.jpg

Any help will be appreciated. Thanks.

[awerby]

Normally, sump pumps are equipped with a float switch - could that work here?