SYMPOSIA PAPER Published: 01 January 1971

Contribution of Hydraulic Fluids to System Contamination


In the continuing investigation of causes of contamination in hydraulic systems, two types of contaminants attributable to hydraulic oils have been observed. The first is the reaction of some hydraulic fluids with water and the forming of precipitates. The second is the inability of some hydraulic oils as delivered to the customers to be filterable. Since this phenomenon is not consistent with all the oils meeting general categories of specifications, more needs to be learned about why some oils generate this type of contamination while others do not.

The test used to differentiate between the (2) types of fluid contaminants is described, and typical data is presented for petroleum based fluids, including single grade and multigrade motor oils, automatic transmission fluids, and hydraulic fluids. Photographs of some of the unusually shaped contaminants are included. The author suggests a test method which will allow the oil manufacturer and oil users to screen oils to eliminate those which may have undesirable characteristics. The author concludes with a request that the oil manufacturers and oil users work together to learn more about the cause of this phenomenon and its elimination.

Author Information

Kirnbauer, E., A.
Pall Corporation, Glen Cove, L. I., N. Y.
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Developed by Committee: D02
Pages: 50–68
DOI: 10.1520/STP44727S
ISBN-EB: 978-0-8031-6041-5
ISBN-13: 978-0-8031-6195-5