METHOD OF ASSESSING STABILITY OF HYDRAULIC FLUIDS FOR AIRCRAFT ENGINEERING Russian patent published in 2020 - IPC G01N33/22 

FIELD: test technology.

SUBSTANCE: invention relates to testing liquids for aircraft hydraulic systems, particularly for evaluating stability of hydraulic fluids. Method comprises filling with working liquid of sealed temperature-controlled container, testing working fluid in specified conditions for a certain period of time and evaluating stability of hydraulic fluid based on change in kinematic viscosity at temperature of 50 °C and acid number. Tested working liquid with volume of 10 ml, 20 ml and 30 ml is placed in a test vessel, test conditions are set: temperature of hydraulic fluid – 50 °C, 100 °C and 150 °C, ultrasonic action on hydraulic fluid with frequency of 22 kHz and amplitude values – 10 mcm, 20 mcm and 30 mcm. Test cycle is formed from 27 stages as required and minimum sufficient set of test modes. After each of the stages, which duration is 5 min, 480 min and 955 min depending on preset value of test time, change in kinematic viscosity at temperature of 50 °C and acid number. At the end of the test cycle, the generalized indices Z_test(et) separately by kinematic viscosity at temperature of 50 °C and acid number of each individual hydraulic fluid, which is compared with generalized value of reference hydraulic fluid.

EFFECT: higher information value and reliability of evaluation.

1 cl, 1 ex, 4 tbl