METHOD FOR DETERMINING SUITABILITY OF LUBRICATING OIL AS SUBSTITUTE FOR ORIGINAL ONE Russian patent published in 2023 - IPC G01N33/30 

FIELD: testing lubricating oils.

SUBSTANCE: method for determining the suitability of a lubricating oil as a substitute for the original includes establishing system parameters for using lubricating oil, measuring the density of the test and standard oils at 0°C, measurement of the kinematic viscosity of the test and standard oils in a temperature range symmetrically extended relative to the operating range by more than 5°C, construction of temperature-viscosity dependencies, calculation of oil volumetric flow rate, oil weight in the oil tank, pipeline length, pipeline cross-sectional area, kinematic viscosity at the current oil temperature, oil density taking into account the temperature ratio of expansion, dynamic viscosity, volumetric flow rate, linear flow rate, mass flow, Reynolds number calculated from kinematic viscosity, Reynolds number calculated from dynamic viscosity, friction loss ratio in turbulent flow, friction loss ratio in laminar flow, Darcy ratio for flow, pressure loss along the length of the pipeline spent on overcoming the force internal friction in the liquid, pressure loss along the length of the pipeline used to impart speed to the flow, the total required pressure to implement the specified parameters of liquid transport, pressure in the pumping part, the height of the hydrostatic column of liquid equivalent to the pressure in the pumping part, linear flow velocity at the end of the line, calculation of volume flow, mass flow and time of single circulation of the filling volume, comparison of the value of the time of single circulation of the filling volume taken at the beginning of the calculation and obtained at the end, calculation of the deviation of pressure and time of single circulation of the filling volume in the hydraulic line when using the test oil from pressure and time single circulation of the filling volume when using standard oil, obtaining IR spectra of the test and standard oils with an absorbing layer thickness of 0.05 to 0.5 mm with recording of absorption bands in the scanning range, including the interval from 700 cm^-1 to 3000 cm^-1, measurement of the peak height of the overtone band at wavelength 2728± 16 cm^-1, measurement of the peak heights of the absorption bands of the obtained IR spectra relative to its zero line, determination of the ratio of the peak heights of the absorption bands of the obtained IR spectra to the measured height of the overtone band, normalization of the ratio values of the peak heights of the absorption bands of the obtained IR spectra of the test and standard oils to the measured height of the overtone band, calculating the difference between the normalized values of the test oil and the standard oil, after which a conclusion is made about the suitability of the test oil as a substitute for the standard oil in accordance with the established criteria for the admissibility of using the test oil, which follow from the technical parameters of hydraulic units and the acceptable values of their variability: when change in pressure in the hydraulic system by no more and no less than 10%, coincidence of the structural and group composition - the tested oil is suitable; when the pressure in the hydraulic system changes by no more and no less than 20%, if there are differences in the structural and group composition, the tested oil is suitable for non-critical units and is of limited suitability for critical units; if the pressure in the hydraulic system changes by more or no less than 20%, if there are significant differences in the structural and group composition, the tested oil is not suitable.

EFFECT: expanding the scope of application and increasing the reliability of the method for determining the suitability of lubricating oil as a substitute for the original one.

2 cl, 8 tbl, 3 dwg, 1 ex