Petroleum and related products - Determination of the ageing behaviour of inhibited oils and fluids using the TOST test - Part 3: Anhydrous procedure for synthetic hydraulic fluids (ISO 4263-3:2015)

2Scope / Description

This part of ISO 4263 specifies a method for determining the aging behavior of synthetic hydraulic fluids of classes HFDU, HEES, HEPG and HETG, which e.g. B. are defined in ISO 12922 [1] and ISO 15380 [2]. Aging is accelerated by the presence of oxygen and metal catalysts at elevated temperatures, and the aging of the liquid is monitored by the change in acid number. Other parts of ISO 4263 establish similar procedures for determining the aging behavior of mineral oil and specified classes of flame-retardant fluids used in hydraulic and other applications. NOTE Other decomposition phenomena, such as the formation of insoluble sludge, corrosion of the catalyst coils or changes in viscosity, may occur and are indicative of oxidation processes in the liquid, but are not included in the oxidation life calculations. The correlation of these occurrences with real-world applications is still being investigated. This test method may be used to compare the oxidation stability of liquids that are not likely to be contaminated with water. However, due to the large number of individual applications in practice, the consistency of the results of this test can differ significantly from the actual performance and can only be assessed during operational use. The precision of this test method for hydraulic fluids is not known due to the lack of interlaboratory test results. This method is not suitable for use in specifications or in the event of a dispute unless appropriate data is available.