Lubrication Tips for Reliability Professionals

April 19, 2001 Subscribers: 6,318

Book Bits

"Since synthetic oils get contaminated with wear metals, carbon soot, combustion residue, and by products of fuels, such as acids and sulphur compounds, in much the same way as petroleum base oils, it may be unreasonable to expect synthetic oils to last longer than petroleum base lubricants.

"Oil levels must be checked periodically, filters serviced or replaced on a regular basis and above all, oil samples should be taken regularly and sent to a competent used oil analysis laboratory for analysis."

This passage comes from the book "The Practical Handbook of Lubrication" by Lloyd Leugner.

Today's Tips

• The pour point is the lowest temperature at which an oil will flow. This property is crucial for oils that must flow at low temperatures. A commonly used rule of thumb when selecting oils is to ensure that the pour point is at least 10 degrees C (20 degrees F) below the lowest anticipated ambient temperature.

• Consider system design in filter selection. If the application has cyclic flow rates, the increase in flow can dramatically alter the efficiency of the element during the surge. If this cylinder cycles at a fast rate, the filter is subjected to extremely high flow rates as the equipment cycles. This can cause leakage past the filter and over the bypass valve as the pressure drop increases, perhaps inducing element collapse.

Each tip published will earn the sender $10. Send your tips to webmaster@noria.com or fax to 918-746-0925.

More Great Tips

Today we are taking a passage from the book "Synthetic Lubricants and High Performance Functional Fluids."

"The use of PAO-based gear oils in industrial settings can lead to important savings in energy consumption, as well as decreased downtime and lower maintenance requirements. The wide range of operating temperatures allows the use of less viscous oils, which results in greater energy efficiency. The relatively low coefficient of friction for PAOs reduces the amount of internal friction created by the normal shearing of an oil film during operation.

"Improved scuffing performance for gear/circulating oils has been demonstrated by Jackson et al., who studied the influence of lubricant traction characteristics on the load at which scuffing occurs. The study compared low traction PAO-based lubricants with mineral oils in additive-free, antiwear, and extreme pressure (EP) formulations. Benefits of 25-220% were observed for the PAO-based synthetic lubricants over mineral oils. The investigators found that low traction PAO-based lubricants uniformly gave higher scuffing loads per unit width than the mineral-based fluids tested at both high and low specific film thickness. PAO-based gear and circulating oils outperformed mineral oil based gear and circulating oils, respectively. PAOs were also shown to be very responsive to additives.

"The advantages of PAOs as lubricants in conveyor applications has been demonstrated by Paton et al. Gearboxes lubricated with a fully synthetic poly(a-olefin)-based gear oil (75W-90) was studied. An all-season PAO-based fluid was chosen for pulley shaft bearing lubrication.

"In wind turbine gearboxes, the high viscosity index of a synthetic fluid would ensure that the change in viscosity with temperature would be less than with equiviscous mineral oils. A further advantage of a synthetic fluid for applications of these types is that synthetics have lower pour points than mineral oils. PAOs provide both excellent viscosity index and low pour point. These properties make them a fluid of choice for applications characterized by wide ranges of operating temperatures."

For more information about "Synthetic Lubricants and High-Performance Functional Fluids" go to: http://www.noria.com/secure/product_detail.asp?catalogid=11

Copyright © 2001, Noria Corporation. All rights reserved. Please do not reprint or host on your website without explicit permission. However, if you found this newsletter helpful, we grant you permission, and strongly encourage you, to e-mail it to a business associate or a friend. Thank you. 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