Breather for upper-bearing oil bath

[electricpete]

(Not stricltly a pump question... but maybe you pump guys can help!)

We have 4000HP 1200RPM vertical motors with oil bath housing the thrust bearing and upper radial bearing (segmented pad). The oil bath is cooled by cooling coils supplied by plant cooling water system. Oil temperature is around 100F.d (slightly warm to touch on external surface).

There is a breather on top of the oil bath compartment whose apparent purpose is to prevent ingress of dirt. (No filter element... just a little bit of labyrinth flow path for air). However, a film of oil appears to be coming from the breather and coating the top of the motor and flowing down the sides (sometimes getting into air intake). As a first attempt to solve the problem we put a pipe nipple between motor oil bath and breather which moved the breather up approx 1' above top of the motor (should prevent any oil splashing). This was unsuccessful.

I'm thinking maybe warm oil vapors enter the breather and then condense on the filter as they hit the cooler atmosphere. Does anyone have any thoughts on this? Any suggestions for type of breather that may eliminate the problem?
Thanks

 

try packing the first vertical portion of your labrynth with metal wool. You probably will not get all of the oil out of the warm outflow, but it will cut down on a lot of it.

 

Hi,

Have you checked the following:

1. All vent passages cleaned of debris?
2. Temp. and thus oil volume has not increased over
previous?
3. No other bearing passages blocked that could cause
pressure increase in bearing?

McMaster Carr makes a beather vent with sintered metal filter. Comes in sizes 1/8" through 2".