Recommendation for breather to prevent vapor condensation 2

[electricpete]

We have 4000hp vertical motors with Kingsbury thrust bearing in upper oil reservoir (50 gallons oil at approx 120F).

The upper reservoir is vented through a breather which is not much more than a mushroom cap. We have oil constantly leaking from that breather. I believe there is some turbulence created within the reservoir due to oil pumping action through ports in the thrust block which supplying oil to upthrust bearing located above the oil level.

We have moved the breather up on a 6" standpipe above top of the motor to eliminate direct splashing but the leakage continues. I believe that the warm oil vapor condenses on the inside of the cooler breather cap where it condenses and unfortunately does not drain back to the sump (bad breather design imho).

Bottom line: Does anyone have successful experience with any commercially-available breather for addressing similar problem ?


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[unclesyd]

I think what your are getting are aerosols and they are coalescing at the cap. We had a similar, major, problem on a large rotary screw compressor. We ended up with a longer stand pipe(3') with a coalescor,with drain line to sump,and one of TRICO’s caps.

I have had very good results from these people over the years with different problems.

http://www.tricomfg.com/faq-search.asp

 

[electricpete]

Thanks unclesyd. Do you know which product of theirs is applicable?

I searched for "coalescing coalescer" (Find ANY word) at the link above and it returns two entries... both are filters which require an upstream coalescing filter to work.

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[unclesyd]

I'll check tomorrow and see what is used on the compressor.
I just called the control room and couldn't find anyone that had any idea of what I was talking about.

 

[unclesyd]

The Coalescor housing was made by York, but now has a homemade coalescor pack made from Metex, metal mesh, and fiberglass.
The housing is 6" dia 8.5" long with a sloping bottom with the return drain coming off the lowest point. The inlet line is 1 1/2"pipe and the return line is 1/4 pipe".
The original vent was a TRICO desiccant type but has been changed to an unknown type of simple construction. The reason for changing the vent type was there has been an increase in air flow due to changes in the seal air system.
More seal air is allowed to vent thru the timing gear housing.

They also have good luck on larger motors that don't have mist lubrication using the expansion chamber concept. You migh want to check this approach out.

 

[electricpete]

Interesting concept the expansion chamber.

This particular motor uses a sightglass that breathes at the top, so any kind of pressure excursion in the upper reservoir would jeapardize the accuracy of the level sightglass.

We could perhaps re-arrange the sightglass to connect the top back to the reservoir to overcome this problem.

However, I still have a vague uneasy concern about other effect that might be created by creating a pressure or vaccum in the upper reservoir. One thing we have encountered due to clogged motor main air inlet filters causes a flow restriction for the fan action of the rotor... creates a higher vacuum in the area of the shaft which draws higher velocity air through the reservoir over standpipe into motor windings. In this particular scenario a cap or expansion chamber would help, but I am just uneasy about changing things the OEM has put in place. In this particular case the oem is out of business which increases my level of unease. Don't want the cure to be worse than the symptom.




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[EdDanzer]

You might look at hydraulic tank filler breathers.

 

[electricpete]

Just to clarify:

What is a hydraulic filler?
Or was hydraulic filter intended?

Either way, is this an application which causes problems in the oil breathing tube in absence of a good breather?

One thing I notice is we have quite a lot of oil reservoirs in our rotating equipment. A lot of it at similar temperatures. None of the other ones I am familiar with (mostly motors) makes a mess like this one. I think maybe it has to do with turbulence within the bearing reservoir which helps get oil vapor mixed into the air.

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[unclesyd]

I would talk to a lubrication salesman that I have had good results with and get some recommendations as to the benefit of changing viscosity and type of oil.

There is another route if I can find some information and that is a small in line filter. We had synthetic oil get into a critical N2 supply system and for several years there was a small straight inline filter at each usage point.

Another point that's way out is the motor running in the designed direction. We had a problem with this big time, in fact it was the oil coming out of the vertical motor that saved a 13 stage pump.

 

[EdDanzer]

A filler, breather is were you fill the hydraulic tank with oil. Most have venting built into the fill cap because of temperature change. Some have addressed condensation build up. If turbulence is a problem, try lowering the oil level some.