Tellus 68 - gearbox foaming

[Shannow]

People,
I've got an application with two identical gearboxes. Large vertical shaft plantetary gear sets, running around 400RPM and 2,000 hp driving through them.

Both are operating under the same conditions at the same time.

One operates normally, and the other's oil foams and looks like expanding foam.

Checked for moisture (cooler leaks), and there is no water present.

Changed the oil (twice), and it still foams.

Any ideas ?

 

[ac_tc]

overfill?

 

[Jim Allen]

Have you compared oil temps? Or at least housing temps with an infra-red gun? Maybe one has a problem that's causing it to run hotter than the other?

 

[bruce381]

different lot number/version of oil or they ARE NOT running undersame conditons in that somwething is diferent. Are they spash only or do they have have a circulaying pump with a filter

 

[Pablo]

I was thinking the lube may be the same "part #" but indeed different lot, one inadvertently without defoamer.

 

[Shannow]

LOL, the maintenance guys "water" test involved letting it sit in a jar.

I'll check back Monday, but IMO a cooler leak.

 

[widman]

Tellus is a hydraulic oil, so first question is why is it in a gear box?

I've seen foaming from worn bearings, water, air (return hitting the reservoir wrong) etc.

The simplest test for water is cut the bottom inch of a beer can and hold it over a candle or lighter. Put a drop of oil on it and watch it. If it sizzles or bubbles rise, it has water. You can substitute a Coke can, but not as refreshing.

 

[bruce381]

Shannow You said "Checked for moisture (cooler leaks), and there is no water present."

that is what i would look for for foaming right off but since it was tested, then latter we see the test was letting the oil set
in a jar. LOL

 

[bruce381]

"'The simplest test for water is cut the bottom inch of a beer can and hold it over a candle or lighter. Put a drop of oil on it and watch it. If it sizzles or bubbles rise, it has water. You can substitute a Coke can, but not as refreshing.""

This test will show a high amount of I think >0.1% or so but less will still cause foaming

 

[Shannow]

Bruce, was a bit annoyed at the "test".

The cooler was vacuum tested, and a small leak found and fixed.

Still foaming...still water IMO.

 

[bruce381]

LOL I though you big time power plant guys used all kinds of super high dollar lab techniques the set the bottle on the shelf is a good one.

One thing I did once was help a customer out that had got some NEW motor oil "wet" >0.5% so he brought it back we put it into a small blend tank and heated it to 200F or so and blew dry air thought it to help strip the water.

Even without boiling the air sparge brough the oil to a nice "fizzy" kinda rolling boil till it dryed to bruce

 

[Shannow]

bruce, we have different sections...only got onto this one as a request from beleagured maintenance team.

My turbine and feed pump oils are sampled every two weeks (Turbine has 20um main filters, 12um bypass filter with vacuum treatment, and a parallel centrifuge)...these pumps sampled around every 3 months.

I've used the dry out treatment years ago, when an MDF plant that I was commissioning went berserk...hydraulics hopping around everywhere...

Was nearly 5 percent water, and the sodium content marched sea water nearly perfectly. One of the installers suddenly "remembered" a container that dropped about 2 feet of water when opened for the first time.

Hooked up a machine (owned by Wynns), and took a continuous bypass for nearly a week, into a vacuum tank, and over fuller's earth to get the system dry...