【国外标准】 Standard Test Method for Dry Filterability of Lubricants and Hydraulic Fluids by Mass Flow Technique

5.1 Precision equipment and high pressure hydraulic machinery require filtered lubricants and fluids to prevent damage from the circulation of hard particulate contaminants. Three types of particulate contaminants are present in lubricants and hydraulic fluids: built in contaminants from the machinery assembly process, generated contaminants from equipment wear, and contaminants that enter from external sources.5.2 The ability of lubricants and hydraulic fluids to retain their filterability is critical for efficient and reliable machine performance. Normally, the pressure differential across a filter will increase gradually as the filter accumulates dirt, sludge, and wear debris. In order to prevent the filter from collapsing, bypass valves in the filter assembly open when the differential pressure gets too high. If a filter becomes blocked by precipitating additives or other contaminants, the bypass valve will open. This can lead to an equipment shutdown or circulation of damaging particles throughout the machine.1.1 This test method covers determination of the dry filterability of lubricants and hydraulic fluids based upon mass flow rate measurements through a 0.8 µm membrane after ageing (Note 1). The procedure applies to lubricants and hydraulic fluids that are formulated with American Petroleum Institute (API) Group I, II, III, IV, and certain V base stocks. Products formulated with water or base stocks that are heavier than water are out of scope.NOTE 1: This test method is similar to ISO 13357 but differs from the ISO method in the manner by which filterability is assessed. In ISO 13357, volume flow rates are used to determine filterability. In this test method, mass flow rates are used. Measurements of filterability based on mass flow rates facilitate automation and can be less susceptible to operator error.NOTE 2: Residual water due to atmospheric conditions or contaminants is in scope for these samples and it is typically low for most in process samples.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.