1、Designation: D6821 17D6821 18Standard Test Method forLow Temperature Viscosity of Drive Line Lubricants in aConstant Shear Stress Viscometer1This standard is issued under the fixed designation D6821; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase 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. Scope*1.1 This test method covers the measurement of the viscosity of drive line lubricants (gear
3、oils, automatic transmission fluids,and so forth) with a constant shear stress viscometer at temperatures from 40 C to 10 C after a prescribed preheat and controlledcooling to the final test temperature. The precision is stated for test temperatures from 40 C to 26 C.1.2 The applicability of this pa
4、rticular test method to petroleum products other than drive line lubricants has not beendetermined.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3.1 This standard uses the SI based unit of milliPascal second (mPas) for
5、 viscosity which is equivalent to centiPoise (cP).1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and dete
6、rmine theapplicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations
7、issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D2983 Test Method for Low-Temperature Viscosity of Automatic Transmission Fluids, Hydraulic Fluids, and Lubricants usinga Rotational ViscometerD3829 Test Method for Predicting
8、 the Borderline Pumping Temperature of Engine OilD4684 Test Method for Determination of Yield Stress and Apparent Viscosity of Engine Oils at Low TemperatureD6896 Test Method for Determination of Yield Stress and Apparent Viscosity of Used Engine Oils at Low TemperatureE563 Practice for Preparation
9、and Use of an Ice-Point Bath as a Reference TemperatureE644 Test Methods for Testing Industrial Resistance ThermometersE1137 Specification for Industrial Platinum Resistance ThermometersE2877 Guide for Digital Contact Thermometers2.2 ISO Standards:3ISO 17025 General Requirements for the Competence o
10、f Testing and Calibration LaboratoriesISO Guide 34 General Requirements for the Competence of Reference Material Producers3. Terminology3.1 Definitions:3.1.1 apparent viscosity, nthe determined viscosity obtained by the use of this test method.3.1.2 digital contact thermometer (DCT), nan electronic
11、device consisting of a digital display and associated temperaturesensing probe.1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.07 on Flow Properties.Current edition approved May
12、1, 2017June 1, 2018. Published June 2017July 2018. Originally approved in 2002. Last previous edition approved in 20142017 asD6821 14.D6821 17. DOI: 10.1520/D6821-17.10.1520/D6821-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.o
13、rg. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is inte
14、nded only to provide the 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 curre
15、nt versionof the standard 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 States13.1.2.1 DiscussionThis device co
16、nsists of a temperature sensor connected to a measuring instrument; this instrument measures the temperature-dependent quantity of the sensor, computes the temperature from the measured quantity, and provides a digital output. This digitaloutput goes to a digital display and/or recording device that
17、 may be internal or external to the device. These devices are sometimesreferred to as “digital thermometers.”3.1.2.2 DiscussionPET is an acronym for portable electronic thermometers, a subset of digital contact thermometers (DCT).3.1.3 Newtonian oil or fluid, nan oil or fluid that at a given tempera
18、ture exhibits a constant viscosity at all shear rates or shearstresses.3.1.4 non-Newtonian oil or fluid, nan oil or fluid that at a given temperature exhibits a viscosity that varies with changingshear stress or shear rate.3.1.5 viscosity, nthe ratio between the applied shear stress and rate of shea
19、r, sometimes called the coefficient of dynamicviscosity.3.1.5.1 DiscussionThis value is thus a measure of the resistance to flow of the liquid. The SI unit of viscosity is the pascal second Pas. Thesubmultiple unit is millipascal seconds (mPas).3.2 Definitions:Definitions of Terms Specific to This S
20、tandard:3.2.1 apparent viscosity,calibration oils, nthe determined viscosity obtained by the use of this test method.those oils thatestablish an instruments reference framework of apparent viscosity versus speed, from which the apparent viscosities of test oilsare determined.3.1.2 digital contact th
21、ermometer (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 instrument; this instrument measures the temperature-dependent quantity of the sensor, computes the t
22、emperature from the measured quantity, and provides a digital output. This digitaloutput goes to a digital display and/or recording device that may be internal or external to the device. These devices are sometimesreferred to as “digital thermometers.”3.1.2.2 DiscussionPET is an acronym for portable
23、 electronic thermometers, a subset of digital contact thermometers (DCT).3.1.3 Newtonian oil or fluid, nan oil or fluid that at a given temperature exhibits a constant viscosity at all shear rates or shearstresses.3.1.4 non-Newtonian oil or fluid, nan oil or fluid that at a given temperature exhibit
24、s a viscosity that varies with changingshear stress or shear rate.3.2.2 shear rate, nthe velocity gradient in fluid flow.3.2.2.1 DiscussionFor a Newtonian fluid in a concentric cylinder rotary viscometer in which the shear stress is measured at the inner cylinder surface(such as the apparatus descri
25、bed in 6.1), and ignoring any end effects, the shear rate is given as follows: 5 2Rs2Rs22Rr2 (1) 5 4piRs2tRs22Rr2! (2)D6821 182where: = shear rate at the surface of the rotor in reciprocal seconds, s-1, = angular velocity, rad/s,Rs = stator radius, mm,Rr = rotor radius, mm, andt = time for one revol
26、ution of the rotor, s.For the specific apparatus being described in 6.1.1, 533t (3)3.2.3 shear stress, nthe motivating force per unit area for fluid flow.3.2.3.1 DiscussionFor the rotary viscometer being described in 6.1, the rotor surface is the area under shear or the shear area. For this test met
27、hod,end effects are not considered.Tr 59.81 M Ro1Rt!31026 (4) 5 Tr2piRr2 h 3109 (5)where:Tr = torque applied to rotor, Nm,M = applied mass, g,Ro = radius of the shaft, mm,Rr = radius of the string, mm, = shear stress at the rotor surface, Pa, andh = height of the rotor face, mm.For the dimensions gi
28、ven in 6.1.1,Tr532 M 31026 (6) 54.5 M (7)3.2.4 test oil, nany oil for which the apparent viscosity is to be determined by this test method.3.2.5 viscosity, yield stress, nthe ratio between the applied shear stress and rate of shear, sometimes called the coefficient ofdynamic viscosity.shear stress r
29、equired to initiate flow.3.2.5.1 DiscussionThis value is thus a measure of the resistance to flow of the liquid. The SI unit of viscosity is the pascal second Pas. Thesubmultiple unit is millipascal seconds (mPas).For Newtonian fluids and some non-Newtonian fluids the yield stress is zero. Anoil can
30、 have a yield stress that is a function of its low-temperature cooling rate, soak time, and temperature.3.2 Definitions of Terms Specific to This Standard:3.2.1 calibration oils, nthose oils that establish an instruments reference framework of apparent viscosity versus speed, fromwhich the apparent
31、viscosities of test oils are determined.3.2.2 test oil, nany oil for which the apparent viscosity is to be determined by this test method.3.2.3 yield stress, nthe shear stress required to initiate flow.3.2.3.1 DiscussionFor Newtonian fluids and some non-Newtonian fluids the yield stress is very smal
32、l.4. Summary of Test Method4.1 A drive line fluid is preheated to 50 C for a specified time and then cooled at a programmed rate (see Table X1.1) to thefinal test temperature and soaked at the final temperature for a defined period of time. At the completion of the soak time, theviscosity is measure
33、d by applying a prescribed torque and measuring rotational speed to determine the apparent viscosity of thesample.D6821 1835. Significance and Use5.1 Viscosity of drive line lubricants at low temperature is critical for both gear lubrication and the circulation of the fluid inautomatic transmissions
34、. For gear oils (GOs), the issue is whether the fluid characteristics are such that the oil will flow into thechannel dug out by the submerged gears as they begin rotating and re-lubricating them as they continue to rotate. For automatictransmission fluids, torque, and tractor fluids the issue is wh
35、ether the fluid will flow into a pump and through the distribution systemrapidly enough for the device to function.5.2 The low temperature performance of drive line lubricant flow characteristics was originally evaluated by the channel test.In this test, a pan was filled to a specified depth of appr
36、oximately 2.5 cm and then cooled to test temperature. The test wasperformed by scraping a channel through the full depth of the fluid and across the length of the pan after it had soaked at testtemperature for a specified time. The time it took the fluid to cover the channel was measured and reporte
37、d. The channel test wasreplaced by Test Method D2983 in 1971.5.3 The results of this test procedure correlate with the viscometric measurements obtained in Test Method D2983.4 Thecorrelation obtained is:V 50.9413VD2983 (8)where:V = the apparent viscosity measured by this test method, andVD2983 = the
38、 apparent viscosity measured by Test Method D2983.5.3.1 The equation was obtained by forcing the fit through zero. The coefficient of variation (R2) for this correlation is 0.9948.6. Apparatus6.1 Mini-Rotary ViscometerAn apparatus that consists of one or more viscometric cells in a temperature contr
39、olled aluminumblock. Each cell, when fitted with the specified rotor, becomes a calibrated rotor-stator set. Rotation of the rotor is achieved by anapplied load acting through a string wound around the rotor shaft. The top bearing plate is fitted with locking pins for holding therotors stationary. T
40、ime of rotation is measured electronically by a device attached to the timing wheel.6.1.1 The mini-rotary viscometric cell for this procedure has the following typical dimensions:Diameter of rotor 15.00 mm 0.08 mmLength of rotor 20.00 mm 0.14 mmInside diameter of cell 19.07 mm 0.08 mmRadius of shaft
41、 3.18 mm 0.13 mmRadius of string 0.1 mm6.2 WeightFor applying mass. Weights are to be in increments of 2.5 g 6 1 %. A minimum of eight weight segments will beneeded for the measurements defined in this test method. One segment will be the weight holder.6.3 Temperature Control SystemThat will regulat
42、e the samples in the cells according to the cooling program described inTable X1.1 and within the tolerances specified in the table.6.4 Temperature Measuring DeviceUse either a DCT meeting the requirements described in 6.4.1 or liquid-in-glassthermometers described in 6.4.2. A calibrated DCT or cali
43、brated low temperature liquid-in-glass thermometer shall be used as thethermometer for temperature measurement below 25 C independent of the instruments temperature control, and shall be locatedin the thermowell.NOTE 1The DCT display device and sensor must be correctly paired. Incorrect pairing will
44、 result in temperature measurement errors and possiblyirreversible damage to the electronics of the display.6.4.1 Digital Contact Thermometer Requirements:Criteria Minimum RequirementsDCT Guide E2877, Class BTemperature range 45 C to 100 CDisplay resolution 0.1 C minimum, preferably 0.01 CSensor typ
45、e RTD, such as a PRT or thermistorSensor,metal sheathed3 mm O.D. with an sensing element less than 30 mm in length to be used with a thermowell sleeve, 6 mm O.D. 58 mm long with a 3 mm hole in center.Sensor,glass sheathed6 mm O.D. with a sensing element less than 12 mm in lengthDisplay accuracy 50 m
46、K (0.05 C) for combined probe and sensorResponse time less than or equal to 8 s as defined in Specification E1137Drift less than 50 mK (0.05 C) per yearCalibration Error less than 50 mK (0.05 C) over the range of intended use.Calibration Range 40 C to 85 C4 SAE Paper 1999013672, “Viscosity of Drive-
47、Line Lubricants by a Special Mini-Rotary Viscometer Technique.”Available from Society ofAutomotive Engineers, 400Commonwealth Dr., Warrendale, PA 15096-0001.D6821 184Calibration Data 4 data points evenly distributed over the range of 40 C to 1 C and included in calibration report.Calibration Report
48、From a calibration laboratory with demonstrated competency in temperature calibration which is traceable to a na-tional calibration laboratory or metrology standards bodyNOTE 2With respect to DCT probe immersion depth, a procedure to determine minimum depth can be found in Guide E2877, Section 5.3,
49、or TestMethods E644, Section 7.6.4.1.1 The DCT calibration driftshall be checked at least annually by either measuring the ice point or against a referencethermometer in a constant temperature bath at the prescribed immersion depth to ensure compliance with 6.4.1. With respect toan ice bath, Practice E563 provides guidance on the preparation and use of an ice bath. However, for this use, variance from thespecific steps, such as water source, is permitted provided preparation is c
