Hydraulic oil with excellent air release and low foaming tendency
AssigneeChevron U.S.A. Inc.
InventorsJohn M. Rosenbaum, Susan M. Abernathy, Stephen J. Miller, Nancy J. Bertrand
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Abstract
This invention provides a hydraulic oil comprising: 1) a lubricant base oil having an average molecular weight greater than 475, a viscosity index greater than 140, and a weight percent olefins less than 10; and 2) an antiwear hydraulic oil additive package. The hydraulic oil of this invention has an air release by ASTM D 3427-03 of less than 0.8 minutes at 50 degrees C., and a sequence II foam tendency by ASTM D 892-03 of less than 50 ml. We describe a process for making the hydraulic oil of this invention, and a method of operating a hydraulic pump without pump cavitation using the hydraulic oil of this invention.
Claims21
A hydraulic oil, comprising:
- a. a lubricant base oil having:
- i. an average molecular weight greater than 475;
- ii. a viscosity index greater than 140;
- iii. a weight percent olefins less than 10;
- and
- b. an antiwear hydraulic oil additive package;
- wherein the hydraulic oil has:
- i. an air release by ASTM D 3427-03 of less than 0.8 minutes at 50 degrees C., and
- ii. a sequence II foam tendency by ASTM D 892-03 of less than 50 ml.
A hydraulic oil, comprising:
- a. between 10 and 99.9 weight percent based on the total hydraulic oil of a lubricant base oil having:
- i. an average molecular weight greater than 475,
- ii. a viscosity index greater than 140,
- iii. a weight percent olefins less than 10;
- and
- b. between 0.1 and 15 weight percent based on the total hydraulic oil of an antiwear hydraulic oil additive package;
- wherein the hydraulic oil has:
- i. an air release of less than 0.8 minutes at 50 degrees C. by ASTM D 3427-03;
- ii. a sequence II foam tendency by ASTM D 892-03 of less than 50 ml;
- and
- iii. a number of minutes to 3 ml emulsion at 54 degrees C. by ASTM D 1401-02 of less than 30.
A process for making a hydraulic oil, comprising:
- a. selecting a waxy feed having:
- i. greater than 75 wt % n-paraffins;
- and
- ii. less than 25 ppm total combined nitrogen and sulfur;
- b. hydroisomerization dewaxing the waxy feed to produce a lubricant base oil;
- c. fractionating the lubricant base oil into one or more fractions;
- d. selecting one or more of the fractions having:
- i. an average molecular weight greater than 475;
- ii. a viscosity index greater than 140;
- iii. a weight percent olefins less than 10;
- and
- e. blending the one or more selected fractions with an antiwear hydraulic oil additive package to produce a hydraulic oil having an air release at 50 degrees C. by ASTM D 3427-03 of less than 0.8 minutes.
Dependencies are inferred from the claim text.