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In This Issue:

• Readers Challenge: Developing a Motor Bearing Regreasing Strategy

• Today's Tip: Oil Levels May be Deceptive

• Book Bits: Consequences of Improper Commissioning

• Lube-Trivia: How Do Additives Deplete?

• Q & A: Which Acid Number Test is Best?

Today's Tip

Oil Levels May be Deceptive

• You can get false oil levels in hung centrifugal pumps if the case is not vented. When the pump is online and the oil heats up, it builds up internal pressures in the head space that can cause the oil level to rise in the case. (Submitted by A.C. Sinitiere, Maintenance Supervisor, Enterprise Products. Thanks A.C.!)
  

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Book Bits

Consequences of Improper Commissioning

From "Insider Secrets to Hydraulics"

Incorrect commissioning during start-up can result in damage through inadequate lubrication, cavitation and aeration. In many cases, this damage will not show itself until the component fails, hundreds or even thousands of hours after the event.

A common misconception among maintenance personnel with limited training in hydraulics, is that because oil circulates through hydraulic components in operation, no special attention is required during installation beyond fitting the component and connecting its hoses. Nothing could be further from the truth.

More information about the book "Insider Secrets to Hydraulics

Lube-Trivia

How Do Additives Deplete?

Test your knowledge and prepare for ICML lubrication and oil analysis certification with Lube-Trivia.

QUESTION: Name four ways a rust inhibitor can deplete from the oil.

For the answer, visit: http://www.lube-tips.com/trivia/20030910.asp

Q & A

Which Acid Number Test is Best?

"In used oil analysis of natural gas engine oils, most original equipment manufacturers (OEM) have total acid number (TAN) as a criteria for an oil change. However, certain gas engine OEMs have strong acid number (SAN) as a criteria for oil change. Why do these OEMs prefer SAN over TAN?"

Strong acid number can be determined using the same methods as total acid number (ASTM D664 or D974). With total acid number, the test titrates to the final inflection end point and determines both strong acids, like sulfuric and nitric acids, and weaker acids like organic acids formed by oil degradation.

Strong acid number, however, titrates to the first inflection point, corresponding to a pH equivalent of around 6, which does not account for weaker acids.

For natural gas engines - particularly those burning sour gas (that is, a high content of sulfurous impurities), or other impure fuel sources like landfill and biogas, SAN can be instructive in determining the degree of contamination due to stronger, more corrosive acids formed by burning lower-quality fuel.

Under these circumstances, it may offer a more precise method of determining a condition-based oil change parameter.

Mark Barnes, Senior Technical Consultant, Noria Corporation

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