Method to exchange oil in a marine and industrial hydraulic system

摘要

The disclosure relates to exchange of mineral oil to biodegradable oil in marine and industrial hydraulic systems. A hydraulic system 100, 200 is filled with a first oil which is to be replaced with a second oil, whereby the first oil normally is a mineral oil and the second oil normally is a biodegradable oil.Specifically a method where a refractometer is used in order to measure the refractive index Ri_1, Ri_2 of a first oil and a second oil in order to determine the level of replacement of the first oil is suggested. When the first oil is replaced with a second oil, there will be a residue part of the first oil left in the hydraulic system 100, 200, whereby the hydraulic system 100, 200 is actually filled with an oil mixture comprising the second oil and the residual part of the first oil. By measuring the refractive index Ri_m of the oil mixture and comparing it with the refractive indices (Ri_1, Ri_2) of the first and the second oil a mixing ratio (r) of the oil mixture can be determined.