With a digital camera, photograph oil samples (requires the use of a transparent sample bottle) and store the images in a trending software for comparison. Record a new oil sample and use it as a baseline. Set the bottle against a white background such as a sheet of paper to maintain a consistent color comparison.

Use the camera in other ways, such as to record images of the machine and sampling point as a means of identifying it in the software, or to record abnormalities such as excessive leakages for easy location by mechanics. Photos are immediate and speak volumes, so use them to good effect in reports and trending software.

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From the book "Lubricating Grease Guide":

Contaminants can deteriorate greases. Unless containers are tightly sealed, prolonged storage increases the possibility that contaminants will enter stored product. The most prevalent contaminant is moisture, which can enter apparently sealed containers of grease, rusting the containers and changing the product. Some greases, such as soda soap greases, tend to soften when contaminated with water. On the other hand, traces of moisture have been known to cause clay greases and calcium complex greases to become firmer.

Appearance changes in storage are not a common problem but can become evident if oxidation causes the surface to darken, if air slowly leaves the product improving clarity, or if water causes the grease to become hazy.

More information about "Lubricating Grease Guide"

"We recently switched electric motor rebuild shops. Since switching, a number of bearings have failed, typically just a few months after putting the motor back into service. For the most part, these failures have been attributable to inadequate lubrication. On closer inspection, the grease appeared to have thinned-out to almost a liquid consistency. We suspected that the rebuild shop was using a grease inferior to our electric motor grease, but they assure us they're using a premium-quality synthetic grease. What is your opinion?"

Without more details, it's hard to attribute an exact root cause. However with greases, one of the most commonly encountered problems is incompatibility between different types of grease made from different thickeners.

For electric motors, the most commonly used greases are made either from a lithium complex soap thickener or polyurea material. While both polyurea and Li complex-based greases can be used in this application, the two are usually considered to be incompatible with each other and should not be mixed unless proper compatibility testing has been performed.

To avoid these types of problems, it is advisable to request that the rebuild shop use the same grease that you plan to use to regrease the bearings, or at the least, indicate the exact type and brand of grease being used, so that you can determine if there are any serious compatibility issues between the two greases.

It is often advisable to provide a tube of grease to the rebuild shop whenever a motor is sent to rebuild to avoid these issues.

Mark Barnes, Noria Corporation

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