In This Issue:

• Up Front: Charged-Up Filtration

• Book Bits: Bearing Care 101

• Today's Tip: How to Improve Oil Sampling

• Q & A: Is Too Much Filtration a Bad Thing?
  

Up Front

Charged-Up Filtration

Davis-Besse Nuclear Power station installed a new bulk lube oil storage rack and grounded it to the station ground grid. We filtered the oil while transferring to the new storage drums. During this process we noticed blue arcs jumping across all the fittings in the piping. When we contacted the rack manufacturer, the first question asked was "Are you filtering the oil"? He informed us that the filter should also be grounded.

The oil passing through the filter media produces a static charge capable of jumping several inches. Installing a ground lead from the filter to the rack solved the problem.

Another plant within our system turned off the lights while transferring oil to its storage drums (installed for several years) and discovered that they had the same condition but hadn't noticed it! (Submitted by James Staudacher, Sr. Performance Engineering, First Energy Advisor. Thanks James!)

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Book Bits

Bearing Care 101

From "Rolling Bearings Handbook and Troubleshooting Guide":

After bearings operate for a period of time, they may develop deposits of lubricant varnish and contamination from the environment. Unused bearings may also become contaminated due to broken packages or dirty storage areas. In some instances, flushing the bearing with clean lubricant while it is in operation provides some cleaning.

When the bearings are very contaminated with dirt and sludge, soak them in kerosene, mineral spirits, or special commercial solvents. Some solvents can be detrimental to nonmetallic cages, seals or other components. After cleaning with solvents, bearings are extremely vulnerable to corrosion or mechanical damage and should be protected or lubricated immediately. Handling with bare hands can corrode the bearing surfaces because of the acidic moisture on the hands. A clean, dry, unlubricated bearing can be easily damaged by the movement between rolling bearings and raceways. Such bearings should never be spun or subjected to shock or vibration before a coating of lubricant or preservative has been applied.

More information about "Rolling Bearings Handbook and Troubleshooting Guide".

Today's Tip

• An effective flushing procedure is critical to generating a sample that is representative of the oil in your system. Statistical analyses show that flushing 5 to 7 times the total volume of the sample port line, valves, etc. is necessary to collect a good, representative sample of the total oil volume, and not just collect the stagnant oil that had pooled in the dead leg created by the sampling port. Noria recommends 10 times to be conservative in ensuring a good sample.

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Q & A

Is Too Much Filtration a Bad Thing?

"A customer of ours is using an external engine oil filtration device designed to remove contaminants down to 1 to 3-micron range while not affecting the additive package. The customer now believes he can extend the recommended oil change interval from 250 hours to 1,000 hours. My question is this: if you remove all the normal wear particles, how can you determine or trend the wear in the engine?"

By sampling after the pump and before the filter, we can still see an increased rate of wear generation with oil analysis.

By reducing the background level of wear particles (noise), it is comparatively easier to detect the abnormal generation of wear particles assuming, of course, that the sample is drawn after the pump but before the filter.

You will also need to set alarms carefully, using statistics to derive level limits and rate-of-change limits. The benefit of engine life extension associated with polishing the oil is considerable and will easily warrant some investment to ensure that oil analysis can still the generation of abnormal wear.

I would advise your client to make sure that any decision to extend the oil drain interval is backed up by oil analysis (oil properties, contamination and wear debris monitoring). It is unwise to arbitrarily extend oil drains unless the decision is supported by data. Excessive particle contamination level is just one reason why we may change the oil.

Drew Troyer, Noria Corporation

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