1、Designation: D7899 13Standard Test Method forMeasuring the Merit of Dispersancy of In-Service EngineOils with Blotter Spot Method1This standard is issued under the fixed designation D7899; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, 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 a procedure for determinationof the merit of dispersancy of diesel crankcase
3、 engine oils aswell as other types of engine oils where pollutants of diversesources such as soot from combustion, metallic particles fromwear, corrosion of mechanical parts, and insoluble productsresulting from the oxidation of the oil may contaminate thelubricant.1.2 The values stated in SI units
4、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, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practic
5、es and determine the applica-bility of regulatory limitations prior to use.NOTE 1It is not the intent of this test method to establish orrecommend normal, cautionary, warning, or alert limits for any machinery.Such limits should be established in conjunction with advice and guidancefrom the machiner
6、y manufacturer and maintenance group.2. Referenced Documents2.1 ASTM Standards:2D7418 Practice for Set-Up and Operation of Fourier Trans-form Infrared (FT-IR) Spectrometers for In-Service OilCondition Monitoring3. Terminology3.1 Definitions:3.1.1 diesel crankcase engine oils, nan engine oil used int
7、he crankcase of the internal combustion diesel engine.3.1.1.1 DiscussionIt may contain additives to enhancecertain properties. Inhibition of engine rusting, depositformation, valve train wear, oil oxidation, and foaming areexamples.3.1.2 diesel engine, na reciprocating or rotary engine inwhich ignit
8、ion of the main fuel charge, as it is introduced to thecombustion chamber, shall be by the heat of compression of thecharge of combustion air, during regular operation of theengine from idle speeds up to full speed, regardless of whethermiscellaneous methods to augment such heat of compressionare us
9、ed to facilitate starting of the engine under normalconditions or under low ambient temperature conditions or lowintake air temperature conditions.3.1.2.1 DiscussionEngines that are designed to operatewith a continuously hot spot or bulb or other device to facilitateignition or combustion, or both,
10、of low cetane fuels, or anyfuels slow to ignite or to burn, or both, shall be considered tobe diesel engines for purposes of this test method.3.1.3 engine oil, na liquid that reduces friction or wear, orboth, between the moving parts within an engine; removesheat, particularly from the underside of
11、pistons; and serves asa combustion gas sealant for piston rings.3.1.3.1 DiscussionIt may contain additives to enhancecertain properties. Inhibition of engine rusting, depositformation, valve train wear, oil oxidation, and foaming areexamples.3.1.4 oxidation, nof engine oil, the reaction of the oil w
12、ithan electron acceptor, generally oxygen, which can producedeleterious acidic or resinous materials often manifested assludge formation, varnish formation, viscosity increase, orcorrosion, or a combination thereof.3.1.5 sludge, nin internal combustion engines, a deposit,principally composed of inso
13、luble resins and oxidation prod-ucts from fuel combustion and the lubricant that does not drainfrom engine parts but can be removed by wiping with a cloth.3.2 Definitions of Terms Specific to This Standard:3.2.1 dispersancythe property that allows oil to suspendand carry away pollutants of diverse s
14、ources such as soot fromcombustion, metallic particles from wear, corrosion of me-chanical parts, and insoluble products resulting from the agingof the oil.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsib
15、ility ofSubcommittee D02.96.02 on Chemistry for the Evaluation of In-Service Lubricants.Current edition approved Dec. 1, 2013. Published January 2014. DOI: 10.1520/D7899-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For A
16、nnual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 A drop of oil is deposited on a piece of spec
17、ific filterpaper held level and not resting on a surface. The filter paperis placed in an oven set at 80 C for 1 h. The oil wicks acrossthe paper. The oil spot is illuminated with a constant andhomogenous LED (light emitting diodes) backlight. A CCD(charge-coupled device) camera positioned on the ot
18、her side ofthe paper takes a picture of the spot in black and white mode.The software analyzes each pixel of the picture. Dispersancycharacteristics of the oil are judged by how far the oil dropspreads, how large the central sooty area is, and how homo-geneous the opacity of the spot is in compariso
19、n with atheoretical reference diameter of 32 mm.5. Significance and Use5.1 Dispersancy is the property that allows oil to suspendand carry away pollutants of diverse sources such as soot fromcombustion, metallic particles from wear, corrosion of me-chanical parts, and insoluble products resulting fr
20、om the agingof the oil.5.2 When poured on a specific filter paper, oil that isproperly dispersing soot and other insolubles produces anevenly graduated spot. The distribution of the different zones(Fig. 1) will reflect the status of oil dispersancy.5.3 While the oil spreads out on the filter paper,
21、the oilcarries contaminants, and due to the lamination phenomenon ofthe oil film, the particles of same size deposit on the paper onthe same concentric zones.5.4 This test method provides a simple technique for con-dition monitoring of the dispersancy property of in-servicelubricants.5.5 An oil that
22、 is properly dispersing soot and other in-solubles produces an evenly graduated blotter (see Fig.2Spot 1).Aring of light debris on the outer circumference ofthe circular spot also indicates that the oil has retained itsdispersancy properties.5.6 A blotter indicating a high soot load, but evengraduat
23、ion, suggests the oil is still fit for service, but should bewatched closely for degradation (see Fig. 2Spot 2).5.7 When dispersancy begins to fail, the insolubles begin toform a dense ring on the exterior of the absorbing oil drop asin Fig. 2Spot 3. A brown or yellow stain on the blotter spotindica
24、tes oxidation.5.8 Fig. 2Spot 4 indicates the characteristic dense blackdot and sharp periphery that indicates sludge and the loss ofdispersancy as the particles have settled in the center and theoil has wicked outward.5.9 From a maintenance perspective, when the ring beginsto form around the exterio
25、r of the oil blotter, it is time to lookat scheduling a drain. If the black dot is allowed to form, thesituation is problematic because the undispersed portion of sootFIG. 1 Oil Spot Example and Scheme of the Distribution of the Different ZonesD7899 132that has deposited upon surfaces will not be re
26、moved by the oilchange. Often, several changes made at frequent intervals willbe required to effectively scour the engine clean. Also, ifdispersancy performance degrades at an unusually rapid pace,a more extensive review of combustion and ring performanceshould be undertaken.6. Apparatus6.1 Positive
27、 Displacement Pipette, Class A to deliver 20 l.6.2 Filter Paper, having the following characteristics:Paper density 84Paper thickness 0.16 mmType QualitativeParticle retention 2 mFiltration SlowFiltration Herzberg 750Material cotton liners and celluloseNOTE 2The filter paper characteristics are crit
28、ical for the quality ofthe results.6.3 Filter Paper Holder, made of two parts of rigid material,with 50 mm 6 1 mm holes, the filter paper is positionedbetween the upper part and the lower part. The minimumdistance between the holes shall be 65 mm to prevent the oilspots from overlapping. See Fig. 3.
29、6.4 Oven, capable of maintaining a temperature of 80 C 64 C. It shall be equipped with shelves to position the paperholders. It shall not be equipped with forced air convection.6.5 Dispersancy Tester3,(Fig. 4) shall be equipped withbacklight illumination, a digital camera connected to a com-puter to
30、 analyze and record the oil spot image, and the abilityto compute the dispersancy number according to the describedmethod.6.5.1 Digital Camera, associated to its dedicated software,type WVGA shall have a minimum resolution of 752 480pixels.6.5.2 Illumination Source, shall provide a uniform light ont
31、he entire surface of the oil spot.6.6 Neutral Density Filter or ND Filter, for instrumentcalibration, to be used to reduce the intensity of light by adefinite ratio, without affecting the tonal rendition of colors.6.6.1 Neutral density filter with 50 % light transmission.6.6.2 Neutral density filter
32、 with 10 % light transmission.NOTE 3Kodak (trademark) Wratten2 filters4have been found satis-factory for this application.6.7 Reference Spots, two reference spots printed in black onthe filter paper specified in 6.2, one with a diameter of 35 mm6 0.2 mm, one with a diameter 20 mm 6 0.2 mm.NOTE 4A sp
33、ecial calibration kit including the two filters and tworeference spots is available from the instrument manufacturer.7. Sampling and Preparation of Samples7.1 It is recommended that in-service oil or lubricantsamples to be analyzed by this test method be sampled usingprocedures outlined in Practice
34、D7418.7.2 Protect samples from excessive temperatures prior totesting.7.3 Do not test samples stored in containers with significantleakage. Discard and obtain a new sample if significant leaksare detected.7.4 When analyzing samples using this test method, shakethe sample vigorously until the sample
35、is adequately homog-enized and no sediment is adhered to the bottom or sides of thecontainer.8. Preparation of Apparatus8.1 Before use, the instrument needs to be calibrated ac-cording to the procedure described in Section 10. This calibra-tion can be performed by the end user.3The sole source of su
36、pply of the apparatus (model DT 10 and DT 100DLDispersancy Tester) known to the committee at this time isAD Systems, P.A. Portesde la Suisse Normande, Alle de Cindais, 14320 Saint andr sur Orne, France,http:/www.adsystems-. If you are aware of alternative suppliers, pleaseprovide this information to
37、 ASTM International Headquarters. Your comments willreceive careful consideration at a meeting of the responsible technical committee,1which you may attend.4The sole source of supply of the apparatus known to the committee at this timeis Kodak Wratten2, http:/. If you are aware of alternative suppli
38、ers,please provide this information to ASTM International Headquarters. Your com-ments will receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.FIG. 2 Oil Spot ExamplesFIG. 3 Filter Paper HolderD7899 1338.2 Before analyzing samples, the instrument s
39、hould beallowed to warm up for at least 15 min to ensure that theanalyzer is stabilized.9. Calibration of Apparatus9.1 The calibration of the instrument shall be performedevery time it is switched on. Perform the calibration accordingto the manufacturers instructions. The camera brightness andcontra
40、st are automatically adjusted by measuring the twostandard filters specified in 6.6. The spot dimension measure-ment is verified by measuring the printed spots specified in 6.7.10. Procedure10.1 Position a new sheet of filter paper in the filter paperholder and place it on the bench.10.2 Shake the s
41、ample vigorously until the sample is ad-equately homogenized and no sediment is adhered to thebottom or sides of the container.10.3 With the positive displacement pipette, sample 20 l ofsample, wipe the outer surface of the pipette tip from excess ofoil, and inject the sample in the center of the ho
42、le provided inthe holder.10.4 If several different samples are tested, repeat steps 10.2and 10.3 with all samples to be tested (Fig. 5). Several differentoil spots can be prepared on the same sheet. If this is the case,it is recommended to write the sample identification under eachspot.10.5 The pape
43、r holder with the paper sheet is then placed inhorizontal position for 60 min 6 2 min in a laboratory dryingoven adjusted to 80 C.10.6 After 60 min 6 2 min, remove the paper holder fromthe oven. (WarningThe paper holder surface is at 80 C.Use protecting gloves to take the holder out of the oven.)10.
44、7 The paper filter is extracted from the holder. After the60 min drying phase at 80 C, the oil spot may continue itsexpansion. In order to obtain precise results, the oil spots mustbe analyzed within a maximum of 60 min after removal fromthe oven.10.8 Key in all sample details. Position the oil spot
45、 in frontof the CCD camera and the image of the oil spot is displayed.The oil spot must be positioned within the displayed red circle.Press the test key to initiate the test. For more details, refer tothe instruction manual of the apparatus manufacturer.FIG. 4 Dispersancy Tester PrincipleD7899 13410
46、.9 Once the test is initiated, the following steps will beachieved:10.9.1 Step 1Oil Spot detection and size measurement.10.9.1.1 The software determines the edges and the centerof the oil spot. r1 and r2 in Fig. 6 are determined by convertingin mm the number of pixels on r1 and r2 lines. The diamete
47、rof the oil spot is determined by the addition of r1 + r2.10.9.2 Step 2Contamination IndexIC calculation.10.9.2.1 The contamination level (IC) is determined byanalyzing the oil spot opacity. The software determines thelevel of gray (from 0 to 255) of each pixel included in the oilspot. The oil spot
48、opacity is the sum of all opacities of all pixelsincluded in the oil spot image divided by the total number ofpixels of the oil spot image. Using an established correlationtable, the software determines the IC corresponding to themeasured opacity. The IC measuring limits are: 0 % to 4.8 %.10.9.3 Ste
49、p 3Merit of DispersancyMD calculation.10.9.3.1 To determine MD, the software needs to calculatetwo intermediary parameters, DB (DB comes from the Frenchterm Dmrite Brut, which means gross demerit) and ratio.10.9.3.2 Homogeneity of soot distribution within the oilspot is assessed by the DB value. The distribution of theparticles in the oil spot is assessed by the ratio value. The DBand the ratio values are not reported. Combination of both DBand ratio gives the value of the merit of dispersancy (MD).MD 5 1 2 DB!Ratio
