ASTM D2619 Test Method for Hydrolytic Stability of Hydraulic Fluids (Beverage Bottle Method)
3. Summary of Test Method
3.1 The sample of 75 g of fluid plus 25 g of water and 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 of copper is measured. Viscosity and acid number changes of fluid and acidity of water layer are determined.
NOTE 2 - Precaution: In addition to other precautions, because this test method involves the use of a glass bottle that may contain approximately 200 kPa (2 atm) of air and water vapor at temperatures up to 93°C, a full face shield and heavy woven fabric gloves should be worn when handling or working with the heated and sealed sample container.
4. Significance and Use
4.1 This method differentiates the relative stability of hydraulic fluids in the presence of water under the conditions of the test. Hydrolytically unstable hydraulic fluids form acidic and insoluble contaminants which can cause hydraulic system malfunctions due to corrosion, valve sticking, or change in viscosity of the fluid. The degree of correlation between this test and service performance has not been fully determined.
