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June
12, 2001 Subscribers: 7,001 |
“I know that both acid number and RPVOT tests are used to determine oil oxidation. What is the difference between the two?”
Strictly speaking, the RPVOT test doesn’t measure oil oxidation but rather the oils resistance to oxidation. The test works by stressing an oil with heat, oxygen, water and a metal catalyst and measuring how long an oil can resist these oxidation forcing factors. The test is used to determine the change in oxidation resistance between new oil and in-service oil.
Acid number on the other hand can be used to determine how oxidized an oil has already become. The test relies on the fact that as an oil oxidizes, it forms carboxylic acids that increase the oils acid number. By comparing the acid number of a used oil sample, with a new oil reference sample, the degree of oxidation can be gauged.
Depending on the circumstances, an oil may have less than 25% remaining resistance to oxidation as determined by the RPVOT test, but may only show a difference in acid number from new of 10-20%.
Overfilling a gearbox sump can be just as damaging as under- filling. Overfilling
may cause air entrainment and foam, overheated oil and leakage due to overflow.
Over time oxidation may occur due to increased temperatures and exposure
to air.
Each tip published will earn the sender $10. Send your tips to webmaster@noria.com or fax to 918-746-0925.
Knowing the potential and probable sources of contaminant helps to establish an effective exclusion program. In reality, three fundamental modes contribute to contamination:
Injected by people - implanted during manufacturing or induced in the field during maintenance, repair, or overhaul operations.
Generated by the system - created tribologically, chemically, or by desorption.
Ingested by the machine - introduced by inhalation of dust, air, and water; encroachment of energy; and migration of microbes from the environment.
For more information about the book "Fluid Contamination Control" go to:
http://www.noria.com/secure/product_detail.asp?catalogid=47
Suggestions, Questions and Tip Submissions
Send questions and tip submissions to: webmaster@noria.com. Each tip published will earn the sender $10.
Other correspondence:
Noria Corporation
1328 E. 43rd Court
Tulsa, OK 74105 USA
Phone: 918-749-1400
Fax: 918-746-0925
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