In This Issue:

• Up Front: Perplexing "Hot" Issue

• Book Bits: Extending Pump Bearing Life

• Today's Tip: Personalization Works

• Q & A: Clean and Re-use Filter Elements?
  

Up Front

Perplexing "Hot" Issue

We have a 1300 gallon centralized lube oil system that supplies ISO 460 lube oil to a chain of 10 gear reducers. To eliminate any water or moisture in the lube oil, we preheat the oil to about 150°F then vacuum moisture with a vacuum system.

When oil analysis results showed low viscosity, phosphorus and zinc levels, we decided to change the oil. A day after the oil change, another sample was taken and analyzed. The results were better, but not as good as they should be.

About a week later a third sample was taken and again, low viscosity, phosphorous and zinc levels.

As it turned out, the heater used to pre-heat the oil had 12 elements that contacted the oil directly to heat the oil. These elements would accumulate residue and were replaced about every six months. This residue of solids on the heating elements was found to be phosphorus and zinc.

Since then, we have replaced the oil heaters with a glycol heat exchanger. The heating elements are inserted into the tank and heat the glycol. The oil passes through tubes in the glycol and is heated to 150°F. The oil makes no contact with the heating elements whatsoever and our oil properties have been holding steady ever since. (Submitted by Delbert Swier, Preventive Maintenance Supervisor, Encore Wire. Thanks Delbert!)

Each Up Front story published will earn the sender $50. Submit a case study, experience or lesson learned. Or e-mail info@noria.com. Let us hear from you.

Book Bits

Extending Pump Bearing Life

From "Machinery Failure Analysis and Troubleshooting":

A rather large number of factors influences lubricating oil degradation and, consequently, pump bearing life. If your centrifugal pumps are equipped with rolling element bearings, there is little doubt that medium viscosity turbine oils (ISO Grade 68) will perform better than the lighter oils originally specified by many pump manufacturers. But by far, the most frequent cause of lube-oil-related failure incidents is water and dirt contamination. With only 20 ppm water in pure mineral oil, bearing surface and rolling element fatigue life is reduced by an incredible 48 percent. Although the fatigue life reduction is less pronounced with inhibited lubricants, there are always compelling reasons to exclude dirt and water from pump bearing housings. Lip seals are a poor choice for centrifugal pump installations demanding high reliability. Face seals represent superior, hermetic sealing and should be given serious consideration.

More information about "Machinery Failure Analysis and Troubleshooting".

Today's Tip

• In the past, we used whatever container we could find and cleaned it as best as we could before filling with oil and taking it to the equipment. Now we are trying to eliminate all cross contamination and debris contamination by having one person responsible for cleaning, refill and labeling of the reusable containers. (usually five gallon pails with pour spouts) But because we run lean and mean it gives little time to return refillable oil containers to the refill station. We tried putting a sticker on the lids that said "Please return this container to the shop". It did not work. Then we labeled lids with "Please return this container to JB " (JB is the lube tech). This worked with nearly 100 percent of the containers making it back.

  Adding a little bit of personalization and ownership to the procedure made it happen. It is human nature to help the individual more than helping the group. (Submitted by Jerry E. Baker, Lube Tech, A. E. Staley. Thanks Jerry!)

Each tip published will earn the sender $25. Submit your tip.

Q & A

Clean and Re-use Filter Elements?

"We have been advised not to re-use filter elements as we currently do, but instead to replace them every 12 months if they have not blocked before then. Is this a ploy by the filter supplier to sell more filters?"

Most re-useable wire mesh strainers are generally ineffective for fine filtration purposes and may become damaged when re-cleaned. Often, larger holes appear in the mesh through mishandling or the mesh is not properly cleaned.

Cleaning of common disposable elements is a false economy as the media weakens with age, thus allowing the reappearance of significant amounts of debris back into the system in the event of a minor pressure surge. In fact, because of vibration and fatigue, in-service elements become susceptible to failure with age, hence the 12-month recommended change. To be sure of the protection provided by your filters, ensure a regular program of particle counting.

In sum, cleaning of filter elements is generally not worth the risk for the minor savings of their reuse. A possible exception includes filter elements specifically designed for reuse by a well-tested cleaning procedure.

Martin Williamson, Senior Technical Consultant, Noria Corporation

Copyright © 2002, Noria Corporation. All rights reserved. If you would like to reproduce a Lube-Tip on your Web site, you must use the entire issue (without sponsorship messages and the training calendar). All links must work. For an example of how you can include Lube-Tips content on your Web site, go to: http://www.lube-tips.com/example.asp. The presence of advertising in Lube-Tips does not constitute an endorsement of the products or services in such ads. Further, because results will vary widely based on a number of factors, Noria Corporation cannot warrant the results, the accuracy or the completeness of any material published herein.

Lube-Tips is published by Noria Corporation. Oil Analysis and Lubrication Experts