In This Issue:

• Up Front: Two Useful Web Sites

• Book Bits: How Water Saturation Levels Vary Between Oils

• Today's Tip: Filter Change Tip
  

• Q & A: Grease Compatibility Issues
  

Up Front

Two Useful Web Sites

I rarely come across Web sites that are truly useful or interesting but these two are worth taking a look at:

www.ReliabilityWeb.com
The Goliath of all maintenance-related Web sites, Reliabilityweb.com delivers a wealth of solutions in areas like alignment, CMMS, lubrication, infrared, RCM, vibration analysis and more. It's a gold mine of free resources including online training, advice from experts, articles, used equipment listings, service providers and more.

www.HowStuffWorks.com
HowStuffWorks is a favorite for aspiring know-it-alls. This Web site explains in plain language everything from "How an Engine Works" to "What Makes Your Knuckles Pop". It's the ultimate site for the technically and terminally curious. The engines section is particularly useful explaining the workings of bearings, gears, gas turbines and more.

Happy surfing!

Mike Ramsey
mramsey@noria.com

Book Bits

How Water Saturation Levels Vary Between Oils

From the book "Fluid Contamination Control":

The amount of water that a given fluid will absorb depends upon its base stock, viscosity, additive package, and temperature. The amount of water that can dissolve in a fluid is termed its saturation level. The saturation level for a hydraulic fluid is 200-300 ppm while for a lubricating oil it is around 500-600 ppm. Oil is cloudy when it is above its saturation level. The saturation level for a synthetic fluid is generally much higher than for a mineral base fluid.

Click here for more information about the "Fluid Contamination Control".

Today's Tip

• When changing a filter element inside a housing, drain all of the oil from the filter housing first. There should be a drain port near the bottom of the housing as well as a port on the top to let air in. This procedure will eliminate debris that was trapped in the filter element from rinsing out when pulled through the oil in a filled housing. This debris will get a free run at your system when restarted because it is already on the down stream side of the new filter. (Tip submitted by Kim Zelkowski, Closed Loop Technologies.)

Each tip published will earn the sender $25. Click here to submit your tip.

Q & A

Grease Compatibility Issues

"I would like to use a lithium complex grease in place of a polyurea grease which I am using at the moment in a high-pressure, hot water pump (Roto-Jet). I have tried this once, but after one year the pump failed, and there was some doubt about whether it was caused by the change of grease. I have recently read that polyurea and lithium greases are compatible. Is this so?" - Roy Turner

Lithium and polyurea greases have generally been found to not be compatible. Tests to assess compatibility relating to worked penetration are covered in ASTM D6185, involving the mixture of the greases in binary combinations such as 75/25 and a 25/75. A 30 penetration number change usually means they are incompatible. Most often, incompatibility means the grease mixtures soften (compared to neat grease). If the mixture gets harder, this is of an even greater concern. Besides changes in grease consistency, there may be other performance losses associated with incompatible mixed greases. These can include oxidation stability, water resistance, rust protection, and AW/EP performance. Remember, incompatibility can be associated with thickeners, base oils, and/or additives that clash.

You need to determine a grease selection that best suits your components and enlist the support of your supplier to recommend a grease that will meet those requirements. A blind comparison run by a reputable lab may be useful as you try to navigate the many options.

Mike Johnson, Senior Technical Consultant, Noria Corporation

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