OT Question About Leaking Fan Shaft Seals:

I have a pair of 80KCFM fans. Both have identical dodge bearings, and both have oil lube cooling. Both also have heat slingers on the shaft (close to the wsb, fan bearing closest to the fan).
Can static pressure be used to disprove the shaft seal leak theory?

One fan is leaking oil. Someone believes that the shaft seal might be failing. They also think that the heat slinger might also be causing the problem as well.

Since I have two fans, and one of them isn't leaking oil at all I used it as a reference. The heat slinger is closer to the wsb on the non-leaking fan. On both units the fins of the slinger are facing the bearings.
I took a manometer and measured the static pressure at the wsb (slinger side), at the same location on both fans (11:00 position as I was facing the fan housing. It's the location where the oil enters the pillow block).
What I found was that the 'leaking' fan had a static pressure range of -0.58 to -0.73"WC, while the 'non leaking' fan had a static pressure range of -0.88 to -1.08"WC.

It seems to me that if the shaft seal had failed the static pressure at the bearing would be much more negative. As it is it wasn't even as negative as the non leaking fan.

Is this flawed reasoning, or does it have merit? I don't know, I'm not a 'fan guy'. lol..

Russ,

Do you or can you take a picture?, what is the discharge temp of the fans?, reason for asking is your journal temp the same?

I don't think you have a large enough WC differential to make a difference between the two, depending the location you were holding the probe you could make that change yourself

I don't see how the heat slinger could make the seal leak??

The seal could change the OD of the shaft and then cause a leak and will happen over a given period of time, how long have they been running?

Hi G.I.T.,
When I took the readings the discharge temps were 205F and 210F. These aren't static values as the fans are located on the outlet sides of two RTOs. The outlet temps vary around 20F during the course of a complete valve cycle.

I agree with you about the heat slinger not being a probable cause, and so does the NY Blower tech I spoke with a few weeks ago (it's a NY Blower AF-Forty fan). He said that if anything the shaft seal could be failing, and the negative static from the fan could pull the oil through the seals.
However the statics I got on Friday don't indicate (imo) that a strong negative static pressure on the bearings is the cause of the leak.
The bearings on the leaking fan were installed easter weekend.
When I adjusted the slinger today, at the fan techs request, I noticed that it was slighty ****ed... maybe something, maybe nothing..
The heat slinger on the leaking fan was further from the wsb than the non-leaking fan. I adjusted its position slightly.

There doesn't seem to be any shaft wear.

I cleaned the area around the bearings and hope to inspect them tomorrow.

By the way I do have some pics of the slinger on the shaft, and the fans in general. If there's something specific you'd like to see just let me know.. Thanks!!