1、Designation: D7596 10Standard Test Method forAutomatic Particle Counting and Particle ShapeClassification of Oils Using a Direct Imaging IntegratedTester1This standard is issued under the fixed designation D7596; the number immediately following the designation indicates the year oforiginal adoption
2、 or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of particleconcentration, particle
3、 size distribution, particle shape, andsoot content for new and in-service oils used for lubricationand hydraulic systems by a direct imaging integrated tester.1.1.1 The test method is applicable to petroleum and syn-thetic based fluids. Samples from 2 to 150 mm2/s at 40C maybe processed directly. S
4、amples of greater viscosity may beprocessed after solvent dilution.1.1.2 Particles measured are in the range from 4 m to$70m with the upper limit dependent upon passing through a 100m mesh inlet screen.1.1.3 Particle concentration measured may be as high as5,000,000 particles per mL without signific
5、ant coincidenceerror.1.1.4 Particle shape is determined for particles greater thanapproximately 20 m in length. Particles are categorized intothe following categories: sliding, cutting, fatigue, nonmetallic,fibers, water droplets, and air bubbles.1.1.5 Soot is determined up to approximately 1.5 % by
6、weight.1.1.6 This test method uses objects of known linear dimen-sion for calibration.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associate
7、d with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D445 Test Method for Kinematic Viscosity of Transparentand Opa
8、que Liquids (and Calculation of Dynamic Viscos-ity)D2896 Test Method for Base Number of Petroleum Prod-ucts by Potentiometric Perchloric Acid TitrationD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4175 Terminology Relating to Petroleum, PetroleumProducts, and LubricantsD4177
9、Practice for Automatic Sampling of Petroleum andPetroleum ProductsD5185 Test Method for Determination of Additive Ele-ments, Wear Metals, and Contaminants in Used Lubricat-ing Oils and Determination of Selected Elements in BaseOils by Inductively Coupled Plasma Atomic EmissionSpectrometry (ICP-AES)D
10、5967 Test Method for Evaluation of Diesel Engine Oils inT-8 Diesel EngineD6304 Test Method for Determination of Water in Petro-leum Products, Lubricating Oils, and Additives by Coulo-metric Karl Fischer TitrationD6595 Test Method for Determination of Wear Metals andContaminants in Used Lubricating O
11、ils or Used HydraulicFluids by Rotating Disc Electrode Atomic Emission Spec-trometryD7279 Test Method for Kinematic Viscosity of Transparentand Opaque Liquids by Automated Houillon ViscometerE2412 Practice for Condition Monitoring of In-ServiceLubricants by Trend Analysis Using Fourier TransformInfr
12、ared (FT-IR) SpectrometryG40 Terminology Relating to Wear and Erosion1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.96 on In-Service Lubricant Testing and Condition Monitoring Services.Current
13、edition approved May 1, 2010. Published August 2010. DOI: 10.1520/D759610.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe
14、ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.2 ISO Standards:3ISO 12103-1 1997 Road vehicles - Test dust for filterevaluation - Part 1: Arizona test dustISO 4406 Hydraulic fluid power Fluids Method forcoding level o
15、f contamination by solid particles2.3 SAE Standards:4SAE AS 4059 Aerospace Fluid Power CleanlinessClassification for Hydraulic Fluids3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 contaminant particles, nparticles introduced froman extraneous source into the lubricant of a ma
16、chine or engine.3.1.2 ISO Codes, nstandard method for coding the levelof contamination by solid particles. This code simplifies thereporting of particle count data by converting the number ofparticles per mL into three classes covering $ 4 m, $ 6 m,and$14 m. ISO 4406 classifications are used as an o
17、ption toreport results for this test method.3.1.3 new oil, noil taken from the original manufacturerspackaging, prior to being added to the machinery. E24123.1.4 particle size, circular diameter, m, ndiameter of acircle with an area equivalent to the projected area of a particlepassing through the d
18、irect imaging integrated tester flow cell.3.1.5 soft particles, nparticles present in the sample thatare related to undissolved oil additives or additive by-products.Without dilution, at room temperature these particles are likelyto be counted by an optical particle counter in a similar mannerto dir
19、t and wear metal particles, air bubbles, and free waterdroplets. They are not considered contaminants as they areeither purposefully left undissolved, or are not harmful to thefluid system, or both.3.1.6 soot, nin internal combustion engines, sub-micronsize particles, primarily carbon, created in th
20、e combustionchamber as products of incomplete combustion. D41753.1.7 wear, ndamage to a solid surface, usually involvingprogressive loss or displacement of material, due to relativemotion between that surface and a contacting substance orsubstances. D4175, G403.1.8 wear particles, nparticles generat
21、ed from wearingsurfaces of a machine or engine.4. Summary of Test Method4.1 Lubricant samples are acquired periodically from amachine or engine being monitored.4.2 Particles are counted and sized by drawing oil through aflow cell. See Fig. 1. The cell is illuminated by a pulsed laser.The duration of
22、 the pulse is sufficiently fast to freeze themotion of the particles in the cell. The pulse frequency is 30Hz. Images of the particles flowing through the cell aremagnified by 4 using a lens between the cell and the CCDvideo chip onto which the images of the particles are focused.Software counts and
23、 sizes each particle. Sizing is done by3Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.4Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale,PA 15096-0001, http:/aero
24、space.sae.org.FIG. 1 Schematic of Direct Imaging Integrated Tester*D7596 102comparison to objects of known linear dimension. The numberof particles per mLis determined by dividing particle counts bythe volume of oil examined. Each image taken corresponds toa small volume of oil equal to the image ar
25、ea, which is 1600 31200 m, multiplied by the cell thickness, nominally 100 m.The actual cell thickness, to the closest m for each cell, isprovided by the manufacturer and is entered into the softwarefor the purpose of calculating the volume of oil examined foreach sample. The total oil volume examin
26、ed is the volume perimage multiplied by the number of images collected.4.3 The direct imaging integrated tester software performsparticle shape recognition of all particles $ 20 m by using aneural network. An algorithm sorts particles into the followingcategories: cutting, fatigue, severe sliding, n
27、onmetallic, fibers,air bubbles and water droplets. Air bubbles and water droplets$ 20 m are eliminated from the particle counting results.Further information regarding wear particle shape recognitionmay be found in Andersons report.5.4.4 Nonmetallic particles are recognized by their partialtranspare
28、ncy. Nonmetallic particles, in thin sections, do notblock light, as do metallic particles. Therefore, particlesdisplaying transparent interior pixels are classified as nonme-tallic. Nontransparent particles are sorted into one of threemetallic categories, namely, cutting, sliding, and fatigue.4.5 Cu
29、tting wear particles are recognized by their elongated,curved, or curly shape.4.6 Sliding wear particles are recognized by being longerthan wide, often with straight edges.4.7 Fatigue particles are recognized by being more or less aslong as they are wide and often with jagged, irregular edges.4.8 Fi
30、bers are recognized by their elongated shape and bypartial transparency indicating nonmetallic composition.4.9 Air bubbles are dark round circles, either completelydark or with small bright centers.4.10 Water droplets are dark round circles with large brightcenters. The difference in appearance betw
31、een air bubbles andwater droplets is due to the much different refractive index ofeach. When present in oil, air bubbles refract much of the lightpassing through them away from the direction of transmission,whereas water droplets, having a refractive index more nearlyequal to that of oil, allow much
32、 of the light incident upon themto transmit through them to the CCD video chip.4.11 Soot is measured by performing an optical extinctionmeasurement with reference to new oil. Absorbance of thelaser light is calculated and calibration is made to diesel engineoil samples with known percentage of soot
33、as determined bythermal gravimetric analysis in accordance with Test MethodD5967, Annex A4.4.12 Condition alerts and alarms, based on trend and level,can be issued for the system being monitored according toparticle count, size distribution, types of particles recognizedand soot content.5. Significa
34、nce and Use5.1 This test method is intended for use in analyticallaboratories including on-site in-service oil analysis laborato-ries. Periodic sampling and analysis of lubricants have longbeen used as a means to determine overall machinery health.Atomic emission spectroscopy (AES) is often employed
35、 forwear metal analysis (Test Methods D5185 and D6595). Anumber of physical property tests complement wear metalanalysis and are used to provide information on lubricantcondition (Test Methods D445, D2896, D6304, and D7279).Molecular spectroscopy (Practice E2412) provides direct in-formation on mole
36、cular species of interest including additives,lubricant degradation products and contaminating fluids suchas water, fuel and glycol. The direct imaging integrated testerprovides complementary information on particle count, particlesize, particle type, and soot content.5.2 Particles in lubricating an
37、d hydraulic oils are detrimen-tal because they increase wear, clog filters and accelerate oildegradation.5.3 Particle count may aid in assessing the capability of afiltration system to clean the fluid, determine if off-linerecirculating filtration is needed to clean the fluid, or aid in thedecision
38、whether or not to change the fluid.5.4 An increase in the concentration and size of wearparticles is indicative of incipient failure or component changeout. Predictive maintenance by oil analysis monitors theconcentration and size of wear particles on a periodic basis topredict failure.5.5 High soot
39、 levels in diesel engine lubricating oil mayindicate abnormal engine operation.6. Interferences6.1 Dirty environmental conditions and poor handling tech-niques can easily contaminate the sample. Care must be takento ensure test results are not biased by introduced particles.6.2 Air bubbles 20 m may
40、be counted as particles givingfalse positive readings. Air bubbles $ 20 m are recognizedand automatically eliminated from the count. Mixing or agi-tating the sample introduces air bubbles into the oil, but thesereadily dissipate with ultra-sonication or vacuum degassing.6.3 Water droplets 20 m may b
41、e counted as particlesgiving false positive readings. If water droplets $ 20 m aredetected in a sample by the direct imaging integrated tester,there is reason to suspect water droplets 20 m are presentand have spuriously increased particle count. Small amounts ofwater in the sample may be negated by
42、 the use of watermasking solvent. See Appendix X1.6.4 Certain additives or additive by-products that are notfully dissolved in the oil, most notably polydimethylsiloxanedefoamant additive, are known to be present as soft particlesthat are not contaminants in the fluid system, but are counted asparti
43、cles by the direct imaging integrated tester. These may benegated by use of a diluting solvent. See Appendix X1.6.5 Samples with viscosity greater than approximately 150mm2/s at 40C when processed by the direct imaging inte-grated tester at room temperature (approximately 20C) mayflow through the te
44、ster too slowly causing the same particle tobe imaged twice. This effect may be negated by diluting the5Anderson, D.P., Wear Particle Atlas (Revised), Prepared for Advanced Tech-nology Office, Support Equipment Engineering Department, Naval Air EngineeringCenter, Lakehurst, NJ, 08733, 28 June 1982,
45、Report NAEC 92 163, approved forpublic release, distribution unlimited.D7596 103sample with clean solvent to lower viscosity. The testersoftware makes provision for input of the dilution factor so thatparticle counts are adjusted and reported for undiluted sample.6.6 Soot levels above approximately
46、1.5 % by weight causeinsufficient laser light to reach the CCD video detector. Thesoftware provides an error message and the sample may bediluted with clear, particle free oil and reprocessed. The testersoftware makes provision for input of the dilution factor so thatparticle counts are adjusted and
47、 reported for undiluted sample.6.7 No correction for oil sample density or for soot densityis made for the soot calculation.6.8 High particle concentrations, in excess of approximately5,000,000/mL, may cause reporting errors. The software pro-vides an error message and the sample may be diluted with
48、clear, particle free oil and reprocessed. The tester softwaremakes provision for input of the dilution factor so that particlecounts are adjusted and reported for undiluted sample.6.9 The software categorizes particles into one of threepossible metallic types. These are cutting, sliding or fatigue.T
49、he software was trained using particles generated by con-trolled wear modes under simulated conditions in a laboratoryusing wear testing equipment. Particles from actual in-serviceoil samples that appear similar in shape are classified into oneof the direct imaging integrated testers categories even thoughthe nature of the particles may be different. For example,nonmetallic particles may be classified into one of the threemetallic classes if the silhouette image captured by the CCDvideo camera contains no transparent interior pixels. Th
