ASTM D4684-2012 Standard Test Method for Determination of Yield Stress and Apparent Viscosity of Engine Oils at Low Temperature《发动机油在低温下表观粘度和弯曲应力测定的试验方法》.pdf
《ASTM D4684-2012 Standard Test Method for Determination of Yield Stress and Apparent Viscosity of Engine Oils at Low Temperature《发动机油在低温下表观粘度和弯曲应力测定的试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM D4684-2012 Standard Test Method for Determination of Yield Stress and Apparent Viscosity of Engine Oils at Low Temperature《发动机油在低温下表观粘度和弯曲应力测定的试验方法》.pdf(18页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D4684 08D4684 12Standard Test Method forDetermination of Yield Stress and Apparent Viscosity ofEngine Oils at Low Temperature1This standard is issued under the fixed designation D4684; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test
3、 method covers the measurement of the yield stress and viscosity of engine oils after cooling at controlled rates overa period exceeding 45 h to a final test temperature between 10 and 40C. The precision is stated for test temperatures from 40to 15C. The viscosity measurements are made at a shear st
4、ress of 525 Pa over a shear rate of 0.4 to 15 s1. The viscosity asmeasured at this shear stress was found to produce the best correlation between the temperature at which the viscosity reached acritical value and borderline pumping failure temperature in engines.1.2 This test method contain two proc
5、edures: Procedure A incorporates several equipment and procedural modifications fromTest Method D468402 that have shown to improve the precision of the test, while Procedure B is unchanged from Test MethodD468402. Additionally, Procedure A applies to those instruments that utilize thermoelectric coo
6、ling technology or directrefrigeration technology of recent manufacture for instrument temperature control. Procedure B can use the same instruments usedin Procedure A or those cooled by circulating methanol.1.3 Procedure A of this test method has precision stated for a yield range from less than 35
7、 Pa to 210 Pa and apparent viscosityrange from 4300 to 270 000 mPas. The test procedure can determine higher yield stress and viscosity levels.1.4 This test method is applicable for unused oils, sometimes referred to as fresh oils, designed for both light duty and heavyduty engine applications. It a
8、lso has been shown to be suitable for used diesel and gasoline engine oils. The applicability topetroleum products other than engine oils has not been determined.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5.1 Except
9、ionThis test method uses the SI based unit of milliPascal second (mPas) as the unit of viscosity. For information,the equivalent unit, centiPoise (cP), is shown in parentheses.for viscosity which is equivalent to, centiPoise (cP).1.6 This standard does not purport to address all of the safety concer
10、ns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D3829 Test Method for Predicting the Borderl
11、ine Pumping Temperature of Engine OilE1137 Specification for Industrial Platinum Resistance Thermometers2.2 ISO Standard:3ISO 17025 General Requirements for the Competence of Testing and Calibration LaboratoriesISO Guide 34 General Requirements for the Competence of Reference Material ProducersISO G
12、uide 35 Certification of Reference Materials1 This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.07 onFlow Properties.Current edition approved Dec. 1, 2008Dec. 1, 2012. Published January 2009April
13、 2013. Originally approved in 1987. Last previous edition approved in 20072008 asD46840708.1. DOI: 10.1520/D4684-08.10.1520/D4684-12.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume inform
14、ation, refer to the standards Document Summary page on the ASTM website.3 Available from International Organization for Standardization (ISO), 1 rue de Varemb, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.This document is not an ASTM standard and is intended only to provide the
15、 user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standar
16、d as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 apparent viscosityvi
17、scosity, nthe determined viscosity obtained by use of this test method.3.1.2 Digital Contact Thermometer (DCT), nan electronic device consisting of a digital display and associated temperaturesensing probe.3.1.2.1 DiscussionThis device consists of a temperature sensor connected to a measuring instru
18、ment; this instrument measures the temperature-dependent quantity of the sensor, computes the temperature from the measured quantity, and provides a digital output or display,or both, of the temperature. The temperature sensing probe is in contact with the material whose temperature is being measure
19、d.This device is sometimes referred to as a digital thermometer.3.1.3 Newtonian oil or fluidfluid, nan oil or fluid that at a given temperature exhibits a constant viscosity at all shear ratesor shear stresses.3.1.4 non-Newtonian oil or fluidfluid, nan oil or fluid that at a given temperature exhibi
20、ts a viscosity that varies withchanging shear stress or shear rate.3.1.5 shear raterate, nthe velocity gradient in fluid flow. For a Newtonian fluid in a concentric cylinder rotary viscometerin which the shear stress is measured at the inner cylinder surface (such as this apparatus, described in 6.1
21、), and ignoring any endeffects, the shear rate is given as follows:Gr 5 2!Rs2Rs22Rr2 (1)5 4pi!Rs2t Rs22Rr2! (2)where:Gr = shear rate at the surface of the rotor in reciprocal seconds, s1, = angular velocity, rad/s,Rs = stator radius, mm,Rr = rotor radius, mm, andt = time in seconds for one revolutio
22、n of the rotor.For the specific apparatus being described in 6.1.1,Gr 563/t (3)3.1.6 shear stressstress, nthe motivating force per unit area for fluid flow. For the rotary viscometer being described, therotor surface is the area under shear or the shear area.Tr 59.81 M Ro1Rt!31026 (4)Sr 5 Tr2pi!Rr2
23、h 3109 (5)where:Tr = torque applied to rotor, Nm,M = applied mass, g,Ro = radius of the shaft, mm,Rt = radius of the string, mm,Sr = shear stress at the rotor surface, Pa, andh = height of the rotor, mm.For the dimensions given in 6.1.1,Tr 531.7 M 31026 (6)Sr 53.5 M (7)3.1.7 viscosityviscosity, nthe
24、 ratio between the applied shear stress and rate of shear, sometimes called the coefficient ofdynamic viscosity. This value is thus a measure of the resistance to flow of the liquid. The SI unit of viscosity is the Pascal secondPas. A centipoise (cP) is one milliPascal second mPas.3.2 Definitions of
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