Active Standard ASTM D7596 Developed by Subcommittee: D02.96.07
Book of Standards Volume: 05.04
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Significance and Use
5.1 This test method is intended for use in analytical laboratories including on-site in-service oil analysis laboratories. Periodic sampling and analysis of lubricants have long been used as a means to determine overall machinery health. Atomic emission spectroscopy (AES) is often employed for wear metal analysis (Test Methods and ). A number of physical property tests complement wear metal analysis and are used to provide information on lubricant condition (Test Methods , , , and ). Molecular spectroscopy (Practice ) provides direct information on molecular species of interest including additives, lubricant degradation products and contaminating fluids such as water, fuel and glycol. Direct imaging integrated testers provide complementary information on particle count, particle size, particle type, and soot content.
5.2 Particles in lubricating and hydraulic oils are detrimental because they increase wear, clog filters and accelerate oil degradation.
5.3 Particle count may aid in assessing the capability of a filtration system to clean the fluid, determine if off-line recirculating filtration is needed to clean the fluid, or aid in the decision whether or not to change the fluid.
5.4 An increase in the concentration and size of wear particles is indicative of incipient failure or component change out. Predictive maintenance by oil analysis monitors the concentration and size of wear particles on a periodic basis to predict failure.
5.5 High soot levels in diesel engine lubricating oil may indicate abnormal engine operation.
1.1 This test method covers the determination of particle concentration, particle size distribution, particle shape, and soot content for new and in-service oils used for lubrication and hydraulic systems by a direct imaging integrated tester.
1.1.1 The test method is applicable to petroleum and synthetic based fluids. Samples from 2 to 150 mm2/s at 40°C may be processed directly. Samples of greater viscosity may be processed after solvent dilution.
1.1.2 Particles measured are in the range from 4 μm to ≥ 70 μm with the upper limit dependent upon passing through a 100 μm mesh inlet screen.
1.1.3 Particle concentration measured may be as high as 5 000 000 particles per mL without significant coincidence error.
1.1.4 Particle shape is determined for particles greater than approximately 20 µm in length. Particles are categorized into the following categories: sliding, cutting, fatigue, nonmetallic, fibers, water droplets, and air bubbles.
1.1.5 Soot is determined up to approximately 1.5 % by weight.
1.1.6 This test method uses objects of known linear dimension for calibration.
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 and health practices and determine the applicability of regulatory limitations prior to use.