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I have a strange question about a Trico Bulb.
Has anyone seen oil back feed into a Trico type oil feed system?
I have a small Union overhung pump where the oil in the bulb turned black. Samples were taken off the drain and bulb. I was able to pull fine metal out of the mixture using a magnet and a glass beaker. We have a real problem with the UV turning the oil, but that doesn't explain the metal in the bulb. I personally have never seen a Trico back feed from the sump to the oilier. We have had problem with windage pulling excessive oil out of the Trico, but never forcing it into the buld. I heard this happen once on a turbine that had a plug put in the vent line. This union pump has no vent in the case. However, the pump seals are just basic dust deflectors so one would think it would vent at this location. The oil system is a simple sump bath design. One big problem is the oil in the bowl appears to have more metal in it than the oil in the sump. This could be explained by settling, but the whole situation sounds a little fishy. I hesitate in making assumption basically because I've never seen this particular problem.
We flushed the oil and I placed marks on the bulb to monitor oil levels. After several days of running the oil level appears to be steady and the oil looks fine.
Oh, there are no signs of bearing defects in the vibration data.

Thanks for any information you might have.

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Hello Waylon,

That does seem like an odd situation...

Try calling the Trico customer support line at: 800-558-7008. They may be able to shed some light on the metal got into the bulb, or put you in touch with their engineers who may be able to help.

If you kept a sample of your oil, most oil analysis labs should be able to perform an analytical ferrograph. This test extracts and lays out the ferris particles enabling you to figure out how they were generated.

You can edit your own posts from an icon on the post itself. But I don't know how to change the topic.


-Kris Sonne
Ron is correct.

Realize that the trico oilers work much like a water cooler that utlizes an upside down water bottle. When water is removed from the inside cup, the level drops to the point where air can enter the bottle to displace a little water. This occurs until the level comes up to the lip of the bottle again, and air can no longer enter.

This principle is at work in the Trico oiler. However, it only works in an orderly fashion if the reservoir is continuously vented to atmosphere, and the level in the reservoir is able to equalize with the level in the cup that the bulb sits in. If there is a sudden depressurization in the reservoir (sometimes on startup), then the level will go up in the reservoir and down in the cup. Excess oil will drip from the bulb, until it reaches the lip again. If the pressures are later equalized, the oil will flow as needed to equalize the heights in the reservoir and the cup; in this case, meaning that some will flow backwards into the cup where it can mix with the bulb.

It is important that a vent is always maintained for any reservoir using a Trico, and that the cup under the bulb is vented as well. You can not rely on a shaft seal, because the movement of the shaft may result in a differential pressure between the reservoir oil and the cup oil, causing differential level. If venting is not an option for the pump, consider the new models Trico has that use sealed piping to connect the reservoir headspace with the oil cup headspace. This ensures that the pressures over the oil are equalized at all times, and that the levels are maintained at the same level.

Rich Wurzbach

Maintenance Reliability Group
We have seen it often as well. My belief is that the discoloartion you see are very small particles suspended in the oil which are so small as to be capable of "diffusing" in much the same way as you would expect dye to diffuse throughout a stagnant pot of water when you put the dye into one corner of the pot.

There is a constant fluid-filled channel between the bubbler and the oil so there I see no reason to believe there would not be continuous diffusion during running and idle conditions.

In a way it is a good thing. One more thing to look at to help watch your machines. We often request oil sample as followup to noting discolored oil In one case we see a lot of brass from either brass oil ring or cage wear which apparently creates a dark greyish color in the oil. Cage was definitely worn upon later inspection.
There are various reasons for "black oil" which are mainly wear of oil rings and oil contamination due to environment / oil degradation. Root cause is other than back feed.

I find same phenomenon in some turbines, pumps & motors.

To reduce back feed, you may change location of the oiler to other side of the pump. In few cases, it helped me in reducing oil leakages. - But any way, in your case it will not solve your problem of oil getting black. :: only you will not see dirty oil through glass.

I have some questions Within how much time oil is turning black ? Which viscosity grade do you use ? Do you replace oil on periodic basic (PM) ?
I came back to add a comment which is the same as Raj said: There are many many reasons for black oil and numerous articles written on that subject. I didn't mean to imply there was one source and on pattern.

The one I described above was horizontal overhung pump. We repeated the scenario several times where after rebuild we saw darkening (greyish/blacking) oil appear gradually over time and oil sample showing brass. The problem finally went away and we fixed so many things with OEM assistance (thermal growth compensation, pipe strain relief, change in oil rings style, change in oil ring groove, change in oil level) that we don't know which one really fixed the problem. Although for sure we know our bearing cages and oil rings were both wearing.

In the above case color was greyish blacking and we found brass. We also have a series of 6 vertical pump motors where several of them are turning darker brown (not at all grey or black) in the oiler for the upper bearing reservoir (sperical roller bearing). Oil samples on those did not show any change in oil characteristics or contaminants. I am still scratching my head to figure out the cause of this one.
Thanks for the input.

Diffusion? Maybe it's something like that, but I haven't been able to find any liturature on th subject. However, the particles were very small.
Here are a few more points to add.
The Trico is the open to atmosphere type.
There appears to be no overflow issues around the cup.
The oil level appears to be stagnant.
The pump is not subject to frequent starts and stops. In fact it runs continuously until something else causes a system shutdown, which isn't very often. The pump maybe out of service once a year and that would be more frequently than scheduled.
There should be no brass cages or slingers in this pump. Small bearing with stamped cages and aluminum held slinger should be what is inside the pump.
Trico has some great technical sheets and bulletins at their website. Two that apply to this discussion include Affects of air movement on Opto-Maticยฎ oilers


Opto-Matic Oiler instructions

Their website is [ ] [/URL]

In my many lubrication audits of power plants and manufacturing facilities, I have consistently found a lack of understanding in maintenance and operations on the proper setting and use of these devices. When used properly, they can be a great tool. When used improperly, they are a common source of decreased bearing life and equipment failure.

In the 1990's I did some work using a fiber-optic probe to view the operation of a cooling water pump lubricated with a trico oiler. We determined that most of the pumps were being underlubricated. Most critical, was that the difference between optimal lubrication (middle of ball at bottom travel) to zero lubrication (below the lip of the outer race) was as little as 3/16" in height adjustment in the oiler ball wingnut setting. After showing the video to the mechanics, they began to exercise much more care in setting these levels.

Take the time to incorporate these instructions and design considerations into your plant's procedures and training, and it can make a big difference in reliability.

Rich Wurzbach
Maintenance Reliability Group, LLC
If you feel that there is no potential for differential levels to account for cross-flow, convection currents is another possibility. The oil in the reservoir will heat up more than the oil in the oiler ball cup. The warmer oil will tend to expand and displace into the ball cup, and if there is sufficient volume in the connection pipe, create some circulation.

I would recommend analyzing the material in the oil. Knowing whether it is wear, contamination, or oxidation byproducts will be very helpful in figuring out the source of this darkening.
Back on the subject of whether simple diffusion is all that is required or something more...

I am remembering now there are several types of Trico oiler. The one I am most familiar with has a simple slant-cut tube on bottom of the bulb which goes approx to the midpoint of a horizontal pipe from the reservoir. The simple principle is when oil in the pipe drops below the top of the slant it allows air to bubble into oiler and some more oil displaced into reservoir. When level rises there bottom of the tube is immersed in oil and no path for air to bubble in and oil level is kept in the oiler due to slight vaccum at top of the oiler. Amount of the vaccum corresponds to height of the oil in the bubbler above reservoir.

That is the setup I was imagining. Again in this setup there is a continuous path between the reservoir and the bubbler.

I am remembering there are some other configurations where this might not be true. One has a "spider" at bottom of the oiler... I never quite unerstood that one.

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