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In This Issue:

• Readers Challenge: Selecting Machines for Oil Analysis

• Book Bits: Contamination and Bearings

• Today's Tip: Gearbox Magnets Are Effective

• Q & A: Know When to Drain and Flush

Readers Challenge

Selecting Machines for Oil Analysis

You have just been hired as the reliability engineer for a manufacturing plant. The plant has more than 4,000 pieces of rotating equipment. How would you go about selecting which components require routine oil analysis, and how would you select the correct series of oil analysis tests for these systems?

Submit your answer at http://www.noria.com/challenge.asp before Tuesday, July 22, 2003. Lube-Tips editors will choose the best answer and the $100 recipient will be announced next week.

Book Bits

Contamination and Bearings

From "The Practical Handbook of Machinery Lubrication"

Bearings operating in a contaminated lubricant exhibit a higher initial rate of wear than those not running in a contaminated lubricant. But, with no further contaminant ingress, this wear rate quickly diminishes as the contamination particles are reduced in size as they pass through the bearing contact area during normal operation.

More information about the book "The Practical Handbook of Machinery Lubrication"

Today's Tip

Gearbox Magnets Are Effective

• In enclosed gear drives with either splash or circulation systems, a magnetic plug or magnetic filter will help collect harmful wear debris. For splash systems, use a magnetic plug or a magnet in the bottom of the case. For circulation systems, a magnetic filter can be used. Removing wear debris can help extend oil and machine life. Wear debris can also be examined upon removal for trouble-shooting purposes.

Each tip published will earn the sender $50. Submit your tip.

Q & A

Know When to Drain and Flush

"Is it really necessary to drain and flush my machine sumps when making a change to an alternative lubricant vendor?"

The simple answer is yes. However, if you are dealing with large volumes and a significant investment, you may avoid the risk of NOT dumping the sump contents. This is what you would need to do:

1. Assess the fluid condition of the fluid in place. RPVOT is a useful tool for verifying residual lifecycle. If the fluid is nearly spent, proceed with the complete change.

2. If fluid life is good, repeat the RPVOT test in portions of 90/10 and 50/50 to see what impact the mixing of the lubricants would have on lubricant health. At the same time, it is useful to run demulsibility, air entrainment and foam tendency tests to assess the ability of a blend of lubricants to dissipate contaminants such as water and air. A simple visual check of oil cloudiness or suspensions is also useful.

3. If the system requires filtration, then perform filterability tests on the mixtures, at the same ratios. If these preliminary tests offer no evidence of performance loss, you could consider proceeding with a top-up approach.

Mike Johnson, Senior Technical Consultant, Noria Corporation

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