EXPLANATION
Hydrolytically unstable hydraulic fluids form acidic and insoluble contaminants which can cause hydraulic system malfunctions due to corrosion, valve sticking, or change in the viscosity of the fluid. This test method differentiates the relative stability of hydraulic fluids in the presence of water under the conditions of the test. The degree of correlation between this test and service performance has not been fully determined. This test method is applicable to petroleum or synthetic-base hydraulic fluids. Water-base or water-emulsion fluids can be evaluated by this test method, but additional water is not added to the sample.
TEST SUMMARY
Seventy-five g of sample is mixed with 25 g of water and along with a copper test specimen, are sealed in a pressure type beverage bottle. The bottle is rotated, end for end, for 48 h in an oven at 93° C (200° F). Layers are separated and insolubles are weighed. Weight change in copper is measured. Viscosity and acid number changes of fluid and acidity of water layer are determined.
TEST PRECISION
Where X is the mean value.
The bias of this test method is not available.