ASTM D6616-21

Standard Test Method for Measuring Viscosity at High Shear Rate by Tapered Bearing Simulator Viscometer at 100 °C

SIGNIFICANCE AND USE
5.1 Viscosity at the shear rate and temperature of this test method is thought to be particularly representative of bearing conditions in large medium speed reciprocating engines as well as automotive and heavy duty engines operating in this temperature regime.  
5.2 The importance of viscosity under these conditions has been stressed in railroad specifications.  
5.3 For other industry needs this method may also be run at 80 °C by using different crossover calibration oils available from the manufacturer. No precision has been determined at this temperature. The equipment is also used at higher temperatures as shown in Test Method D4683 and CEC L-36-90 (also referenced from IP 370).
SCOPE
1.1 This test method covers the laboratory determination of the viscosity of engine oils at 100 °C and 1·106s–1 using the Tapered Bearing Simulator (TBS) viscometer.2
Note 1: This test method is similar to Test Method D4683 which uses the same TBS viscometer to measure high shear viscosity at 150 °C.  
1.2 The Newtonian calibration oils used to establish this test method range from approximately 5 mPa·s (cP) to 12 mPa·s (cP) at 100 °C and either the manual or automated protocol was used by each participant in developing the precision statement. The viscosity range of the test method at this temperature is from 1 mPa·s (cP) to above 25 mPa·s (cP), depending on the model of TBS.  
1.3 The non-Newtonian reference oil used to establish the shear rate of 1·106s–1 for this test method has a viscosity of approximately 10 mPa·s at 100 °C.  
1.4 Application to petroleum products other than engine oil has not been determined in preparing the viscometric information for this test method.  
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. This test method uses the milliPascal second (mPa·s) as the unit of viscosity. This unit is equivalent to the centiPoise (cP), which is shown in parentheses.  
1.6 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, health, and environmental practices and to determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Dec-2020
• ICS: 17.060 - Measurement of volume, mass, density, viscosity
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.07 - Flow Properties

Relations

• Refers: ASTM D4683-20 - Standard Test Method for Measuring Viscosity of New and Used Engine Oils at High Shear Rate and High Temperature by Tapered Bearing Simulator Viscometer at 150 °C
• Effective Date: 01-Jun-2020
• Refers: ASTM D4741-17 - Standard Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer
• Effective Date: 01-Jan-2017
• Refers: ASTM D4683-13 - Standard Test Method for Measuring Viscosity of New and Used Engine Oils at High Shear Rate and High Temperature by Tapered Bearing Simulator Viscometer at 150 °C
• Effective Date: 01-Oct-2013
• Refers: ASTM D4741-13 - Standard Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer
• Effective Date: 01-Oct-2013
• Refers: ASTM D4741-12 - Standard Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer
• Effective Date: 01-Nov-2012
• Refers: ASTM D4683-10 - Standard Test Method for Measuring Viscosity of New and Used Engine Oils at High Shear Rate and High Temperature by Tapered Bearing Simulator Viscometer at 150 <span class='unicode'>&#x00B0;</span>C
• Effective Date: 01-Oct-2010
• Refers: ASTM D4741-06 - Standard Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer
• Effective Date: 01-May-2006
• Refers: ASTM D4683-04 - Standard Test Method for Measuring Viscosity at High Shear Rate and High Temperature by Tapered Bearing Simulator
• Effective Date: 01-Feb-2004
• Refers: ASTM D4741-00 - Standard Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer
• Effective Date: 10-Dec-2000
• Refers: ASTM D4741-96 - Standard Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer
• Effective Date: 10-Dec-2000
• Refers: ASTM D4683-96 - Standard Test Method for Measuring Viscosity at High Shear Rate and High Temperature by Tapered Bearing Simulator
• Effective Date: 01-Jan-1996

Overview

ASTM D6616-21 is the Standard Test Method for Measuring Viscosity at High Shear Rate by Tapered Bearing Simulator (TBS) Viscometer at 100 °C. Developed by ASTM International, this method provides a laboratory procedure to determine the viscosity of engine oils at a controlled high shear rate (1·10⁶ s⁻¹) and temperature (100 °C) using the TBS viscometer. Accurate viscosity measurements under these conditions are essential for evaluating engine oil performance, particularly in environments simulating engine bearing operation.

Engine oils operate under rigorous conditions, and their viscosity at high shear rates and elevated temperatures is a critical indicator of their ability to provide adequate lubrication and protection. ASTM D6616-21 is widely recognized and referenced in industrial and railroad specifications for its relevance in assessing oils under realistic high-stress conditions.

Key Topics

• High Shear Rate Viscosity: The test measures viscosity at 100 °C and a shear rate of 1·10⁶ s⁻¹, simulating engine bearing conditions.
• Tapered Bearing Simulator Viscometer: Utilizes specialized equipment with calibrated Newtonian and non-Newtonian reference oils to deliver precise viscosity results across a typical range of 1 to 25+ mPa·s (cP), depending on the TBS model.
• Calibration and Reference Materials: The method depends on certified Newtonian and non-Newtonian oils for initial and routine calibration, ensuring reliability and reproducibility across laboratories.
• Industry Recognition: The procedure is highlighted in railroad and heavy-duty industrial specifications due to its proven capability to represent real-world engine operating scenarios.
• Standardized Units: Results are reported in milliPascal seconds (mPa·s), aligned with international SI units for consistency and direct comparison.
• Flexible Protocols: The test can be run manually or via automated procedures, accommodating modern laboratory practices.

Applications

Engine Performance Evaluation

• Automotive and Heavy-Duty Engines: Ensures engine oils provide adequate lubrication at temperatures and shear rates typical of engine bearings, reducing wear and extending equipment life.
• Medium-Speed Reciprocating Engines: Particularly relevant for railroads and industrial engines, where operating conditions demand precise control of oil viscosity.
• Used Oil Analysis: The standard supports both new and used oil testing, aiding maintenance programs and failure analysis.

Research and Development

• Formulation Benchmarking: Oil manufacturers use the method to compare new formulations, optimize additive packages, and ensure compliance with customer and regulatory demands.
• Quality Control: Refineries and oil blenders incorporate ASTM D6616-21 into quality assurance programs to certify each production batch.

Compliance and Specification

• Railroad and Industrial Standards: The method is frequently referenced in equipment manufacturer and industry standards, adding confidence in selection and use of lubricants.
• Global Trade & Regulations: Conformity to ASTM D6616-21 supports engine oil approval for international markets, meeting WTO standardization principles.

Related Standards

• ASTM D4683: Measures high shear viscosity at 150 °C using the same TBS viscometer, suitable for higher temperature regimes.
• ASTM D4741: Utilizes the Tapered-Plug Viscometer for high temperature, high shear viscosity of lubricants.
• CEC L-36-90: European method for measuring lubricant viscosity under high shear, frequently cross-referenced in conjunction with ASTM methods.
• IP 370: Energy Institute test for lubricant viscosity under high shear using the Ravenfield Viscometer.

Adopting ASTM D6616-21 ensures reliable, internationally recognized measurement of engine oil viscosity at high shear rates, supporting performance assessment and regulatory compliance in the automotive, transportation, and industrial sectors.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6616 − 21
Standard Test Method for
Measuring Viscosity at High Shear Rate by Tapered Bearing
Simulator Viscometer at 100 °C
This standard is issued under the fixed designation D6616; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This test method covers the laboratory determination of
6 –1 ization established in the Decision on Principles for the
the viscosity of engine oils at 100 °C and 1·10 s using the
2 Development of International Standards, Guides and Recom-
Tapered Bearing Simulator (TBS) viscometer.
mendations issued by the World Trade Organization Technical
NOTE 1—This test method is similar to Test Method D4683 which uses
Barriers to Trade (TBT) Committee.
the same TBS viscometer to measure high shear viscosity at 150 °C.
2. Referenced Documents
1.2 The Newtonian calibration oils used to establish this test
method range from approximately 5 mPa·s (cP) to 12 mPa·s
2.1 ASTM Standards:
(cP)at100 °Candeitherthemanualorautomatedprotocolwas
D4683 Test Method for Measuring Viscosity of New and
used by each participant in developing the precision statement.
Used Engine Oils at High Shear Rate and High Tempera-
The viscosity range of the test method at this temperature is
ture by Tapered Bearing Simulator Viscometer at 150 °C
from 1 mPa·s (cP) to above 25 mPa·s (cP), depending on the
D4741 Test Method for Measuring Viscosity at High Tem-
model of TBS.
peratureandHighShearRatebyTapered-PlugViscometer
4,5
2.2 Coordinating European Council (CEC) Standard:
1.3 The non-Newtonian reference oil used to establish the
6 –1
CEC L-36-90 The Measurement of Lubricant Dynamic
shear rate of 1·10 s for this test method has a viscosity of
Viscosity under Conditions of High Shear
approximately 10 mPa·s at 100 °C.
6,5
2.3 Energy Institute Standard:
1.4 Application to petroleum products other than engine oil
IP 370 Test Method for the Measurement of Lubricant
has not been determined in preparing the viscometric informa-
DynamicViscosityUnderConditionsofHighShearUsing
tion for this test method.
the Ravenfield Viscometer
1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3. Terminology
standard. This test method uses the milliPascal second (mPa·s)
3.1 Definitions:
as the unit of viscosity.This unit is equivalent to the centiPoise
3.1.1 density, n—mass per unit volume.
(cP), which is shown in parentheses.
3.1.2 Newtonianoilorfluid,n—anoilorfluidthatatagiven
1.6 This standard does not purport to address all of the
temperature exhibits a constant viscosity at all shear rates or
safety concerns, if any, associated with its use. It is the
shear stresses.
responsibility of the user of this standard to establish appro-
3.1.3 non-Newtonian oil or fluid, n—an oil or fluid that
priate safety, health, and environmental practices and to
exhibits a viscosity that varies with changing shear stress or
determine the applicability of regulatory limitations prior to
shear rate.
use.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee D02 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Standards volume information, refer to the standard’s Document Summary page on
Subcommittee D02.07 on Flow Properties. the ASTM website.
Current edition approved Jan. 1, 2021. Published January 2021. Originally Available from Coordinating European Council (CEC), Services provided by
approved in 2001. Last previous edition approved in 2020 as D6616 – 20a. DOI: Kellen Europe, Avenue Jules Bordet 142 - 1140, Brussels, Belgium, http://
10.1520/D6616-21. www.cectests.org.
2 5
Available from Tannas Co., 4800 James Savage Rd., Midland, MI 48642. This This test equipment is identical to that described in CEC L-36-90 (under the
viscometer and associated equipment as listed in the research report was used to jurisdiction of the CEC Engine Lubricants Technical Committee) and IP 370
develop the precision statement. To date, no other equipment has demonstrated, references CEC L-36-90.
throughASTM International interlaboratory testing, the ability to meet the precision Available from Energy Institute, 61 New Cavendish St., London, W1G 7AR,
of this test. This is not an endorsement or certification by ASTM International. U.K., http://www.energyinst.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6616 − 21
3.1.4 shear rate, n—velocity gradient perpendicular to the 4. Summary of Test Method
direction of flow.
4.1 A motor drives a tapered rotor closely fitted inside a
matched tapered stator. Appropriate technique establishes op-
3.1.5 shear stress, n—the force per unit area in the direction
6 –1
eration of the viscometer to yield 1·10 s at a temperature of
of the flow.
100 °C at which point test oils are introduced into the gap
3.1.6 viscosity, n—the ratio between the applied shear stress
between the spinning rotor and stationary stator. The rotor
and rate of shear which is sometimes called the coefficient of
exhibits a reactive torque to the viscous resistance of each test
dynamic viscosity and is a measure of the resistance to flow of
oil and the value of this torque response is used to determine
the liquid.
the apparent viscosity of the test oil at 100 °C.
3.1.6.1 apparent viscosity, n—the viscosity of a non-
Newtonianfluidatagivenshearrateorshearstressdetermined 5. Significance and Use
by this test method.
5.1 Viscosity at the shear rate and temperature of this test
method is thought to be particularly representative of bearing
3.2 Definitions of Terms Specific to This Standard:
conditionsinlargemediumspeedreciprocatingenginesaswell
3.2.1 idling oil , n—an oxidatively stable Newtonian oil
as automotive and heavy duty engines operating in this
injected into the operating viscometer stator when the instru-
temperature regime.
mentislikelytobeheldforperiodsoftimegreaterthan30 min
and up to two weeks at 100 °C. Use of this oil prevents stator
5.2 The importance of viscosity under these conditions has
deposits from additives, which may decompose after longer been stressed in railroad specifications.
exposure times in the operating viscometer and permits con-
5.3 For other industry needs this method may also be run at
tinuous operation of the viscometer without need to shut the
80 °C by using different crossover calibration oils available
instrument off.
from the manufacturer. No precision has been determined at
this temperature. The equipment is also used at higher tem-
3.2.2 Newtonian Reference Oil , n—a specially blended
Newtonian oil that has the same viscosity at 100 °C as the peratures as shown in Test Method D4683 and CEC L-36-90
(also referenced from IP 370).
non-Newtonian reference oil of 3.2.3.
3.2.3 non-Newtonian reference oil , n—a specially formu-
6. Apparatus
lated non-Newtonian oil, identified as NNR-10, having a
6 –1
6.1 Tapered Bearing Simulator Viscometers (TBS)—Avis-
selected apparent viscosity at 1·10 s shear rate. The oil is
cometer consisting of a motor connected to a slightly tapered
used to establish an operating gap between the rotor and stator
6 –1
rotor that fits into a matched stator. Several models of the TBS
which will produce 1·10 s shear rate when the rotor height is
are in use. All of these are capable of analyzing test oils at
adjustedtogiveatorqueoutputequivalenttothatofthespecial
100 °C but earlier models are more limited in their upper
reference oil described in 3.2.2.
viscosity range.
3.2.4 reciprocal torque intersection, 1/T,n—the rotor posi-
i
6.2 Different models of the tapered bearing simulator (TBS)
tion on the micrometer defined by the intersection of two
have the following upper levels of operating viscosities at
straight lines generated by the reciprocal torque method using
6 –1
1·10 s shear rate:
the Newtonian reference oil of 3.2.2 and non-Newtonian
6.2.1 Model Series 400 (similar to Fig. 1)—;14 mPa·s
reference oil of 3.2.3. Reciprocal torque versus rotor height
(cP), dual speed.
measurements on both oils gives straight lines whose
6.2.2 Model Series 500 (Fig. 1)—;16 mPa·s (cP) single
intersection, 1/T, establishes the desired rotor position for
i
6 –1
speed.
operation at 1·10 s shear rate.
6.2.3 Model Series 600 (Fig. 2)—;100 mPa·s (cP) (usually
3.2.5 reference Newtonian calibration oils , n—specially
liquid cooled), dual speed.
chosen Newtonian oils used to determine the viscosity-torque
6.2.4 Model Series SS (SuperShear) (similar to Fig. 1)—
relationship of the TBS viscometer at 100 °C from which the
;20 mPa·s (cP), multi-speed.
viscosity of an unknown oil is calculated.
6.2.5 Model Series 2100 E (Fig. 3)—;20 mPa·s (cP) (see
Note 2), multi-speed.
3.2.6 rotor height (rotor position), n—the vertical position
of the rotor relative to the stator and measured by the platform
NOTE 2—TBS Models 500, 600, and SS use a so-called bouncer to
micrometer.
automate unloading and reloading the load cell just before taking a torque
reading. (All automated units apply the bouncer at the appropriate point of
3.2.6.1 stored rotor height (rotor position), n—the rotor
operation as part of their program.) If a bouncer is not on the TBS model
position with the rotor 0.50 mm above the rubbing contact
used (Model 400), the effect is generated by placing the thumb on the
position (see 3.2.7) when the instrument is shut down. brass weight pin and turning the turntable slightly in a clockwise direction
and quickly releasing the turntable.The bearingless Models 2100 E do not
3.2.7 rubbing contact position, n—the rotor height deter-
require unloading the cell since there is no turntable bearing.
mined when the tapered rotor is lightly brought into contact
6.3 Automated System for Calibration, Injection, and Data
with the similarly tapered stator.
Analysis Programs—An automated program for the Tapered
3.2.8 test oil, n—any oil for which the apparent viscosity is Bearing Simulator, simulating the manual method has been
to be determined by this test method. used.
D6616 − 21
FIG. 1 Tapered Bearing Simulator Viscometer Model 500
FIG. 2 High Torque Tapered Bearing Simulator Viscometer Model 600
6.4 Console—The console shown in Fig. 4 is similar in stator-heating element, and motor. They also contain the
Models 400, 500, and 600. Consoles for Series SS and 2100 E circuitry for regulating and monitoring the temperature of the
haveprovisionsforchangingmotorspeed.Allconsolescontain oil in the stator as well as the amplifier and digital readout of
the power source for the load cell, thermoregulator circuit, the load cell.
D6616 − 21
FIG. 3 Multi-Speed Tapered Bearing Simulator Viscometer Model 2100E
FIG. 4 Control Console for Tapered Bearing Simulator Viscometer Models 400, 500, and 600
NOTE 3—The thermoregulator circuit of the TBS viscometers has
former but must be modified for the latter according to
evolved as improvements have been made in the solid-state temperature
directions from the manufacturer.
controller and heater. To achieve the 5 min analysis time specified in this
test method requires a late model solid-state controller with automatic
6.6 Glass Syringe—A 50 mL glass syringe equipped with a
reset coupled to a thermo-foil stator heater with small heat inertia or a
Luer needle lock fits the tip of the filling tube for injection of
fast-responding thermoregulated liquid bath.
test oil into the test cell. Smaller glass and plastic syringes can
6.5 Cooling Systems—Two cooling systems are available
beusedifanyairbubbleinthefilltubecausedbytheexchange
for TBS viscometer work at 100 °C: forced air cooling and
of syringes is first pulled up into the next syringe to be used.
liquid bath cooling. The stator housing is prepared for the
D6616 − 21
TABLE 1 Reference Oil Viscosities at 100.0 °C
6.7 Filter Assembly—A unit made of a filter holder and
A
nominal 10 µ filter is interposed between the syringe and the Reference Oil Characteristic Nominal Viscosities
6 –1
mPa·s at 1·10 s
filling tube to remove particles capable of damaging the
R-2200 Newtonian ;3
rotor/stator cell.
R-2300 Newtonian ;5
R-2350 Newtonian ;7
6.8 Data Recording Equipment—Some form of recording
R-2400 Newtonian ;10
the torque and temperature data produced by the tapered
R-2450 Newtonian ;12
B
NNR-10 Non-Newtonian ;10
bearing simulator is desired in order to (1) determine torque/
A
temperature equilibrium and (2) determine the torque with Contact supplier for certified value of Reference Oil.
B 6 –1
Special reference oil closely equivalent to R-2400 at a value of 1·10 s shear
sufficient precision to calculate viscosity to the second decimal
rate.
place. Early in the use of the TBS viscometer, a strip-chart
recorder was used, later an automated, computer-based record-
ing system was developed with both a computer-simulated
7.5 Source of moderate pressure (<100 PSI) dry air or
strip chart and with data digitally recorded.
nitrogen.
NOTE 4—Although the console has a torque indicator that can be used
for determining viscosity, it has been found that the small oscillatory
NOTE 6—Depending on room temperatures, higher torque levels at
6 –1
variation of torque with time makes desirable the recording and analysis 100 °C and 1·10 s may require air or other gas cooling. Use of dry gas
of the torque output more precise, particularly when determining torque
is required (to keep moisture from entering the stator housing).
equilibrium.
8. Sampling
6.8.1 Strip-chart Recorder:
6.8.1.1 If a strip-chart recorder is used to record the torque 8.1 Fifty millilitres of a representative sample of fresh or
and temperature output signals, use the manufacturer’s direc- used test oil is placed in a 50 mL syringe equipped with
tions for calibrating and setting up the strip chart for recording attached filter holder and 10 µ filter disk in preparation for
torque/temperature data (see Note 5). The torque reading must injection into the TBS viscometer.
be in milliVolts and the temperature in °C with a full-scale
NOTE 7—It is important to always use a filter and filter disk to prevent
chart range of 20 °C to 120 °C.
larger particles from entering the rotor-stator gap. However, it is also
6.8.1.2 Use a chart speed of 1 cm⁄min for recording.
important to note that the TBS viscometer will work with heavily particle
laden used oils as long as they are passed through the 10 µ filter.
6.8.1.3 Set and, when necessary, reset, the strip chart torque
voltage to that which will permit recording the torque as much
9. Preparation of Apparatus
as possible on the upper two-thirds of the chart paper for
maximum sensitivity. 9.1 Set up stator cooling method, air or liquid, according to
the manufacturer’s directions.
6.8.1.4 Factor the resulting voltage values to calculate the
correct values of torque.
NOTE 8—When analyzing relatively viscous oils, stator cooling is
necessary. This is particularly the case at lower operating temperatures
NOTE 5—Although the digital information from the torque output meter
such as 100 °C where simple radiation from the stator through the stator
ontheviscometerconsolecanbe,andis,usedforrecordingadditionaltest
housing is not sufficient to carry away the heat generated by viscous
information, it is desirable to use a two-pen, strip-chart recorder or its
resistance to shear.
computer equivalent since this provides a continuous torque/temperature
record of torque/temperature equilibrium necessary for precision in
9.1.1 Air Cooling—Connect cooling air tubing to the ports
calibration and in calculating viscosity.
on the stator housing and the back of the console following
6.8.2 Computer Accumulation of Torque and Temperature
directions given by the manufacturer in the Owner’s Manual.
Data—Computer recording of digital data can also be used for
This will permit use of the flow meter on the left side of the
the test method. Such programs should show data for both
console to adjust the cooling-air flow rate.
torque and stator temperature. Torque information should be
9.1.1.1 Set the airflow rate at 100 SCFH.
capable of permitting the calculation of viscosity to the second
NOTE 9—Once airflow rate has been set, it is important that this level
decimal place.
bemaintainedthroughoutcalibrationandoperation.Ifdesired,theairmay
be passed through a copper coil in a chilling bath containing water, ice, or
7. Materials
dry ice, as necessary, to obtain desired stator temperature. The cooling
7.1 Reference Newtonian Calibration Oils, Newtonian oils
level must be kept constant.
of known dynamic viscosity at 100 °C. Table 1 shows the
9.1.2 Liquid Cooling—Connect liquid cooling bath tubing
dynamic viscosity values of five Newtonian oils used in
from bath pump to the stator housing and the back of the
developing the information for this test method.
console using insulated tubing according to the manufacturer’s
7.2 Idling Oil—See 3.2.1 for information and use.
directions.
7.3 Non-Newtonian Reference Oil, essential in setting the 9.2 If some days or weeks have elapsed since last use of the
6 –1
rotor/stator gap to 1·10 s shear rate. The nominal level of
TBSviscometer,followthemanufacturer’sinstructionsregard-
apparent viscosity of non-Newtonian reference oil, NNR-10 ing set-up and alignment of the rotor in the stator, checking the
used in applying this test method is given in Table 1.
accuracy of the RTD and, if necessary, adjusting to 100.0 °C.
Shut the power off and go to 9.3.
7.4 Polar Solvent, such as dimethyl sulfoxide is used to
dissolveanydepositsontherotor/statorsurfacesafterextended
NOTE 10—Directions for preparation of the tapered bearing simulator
use. viscometer and console are supplied with the equipment. One of the most
D6616 − 21
important directions to be followed is the alignment of the rotor and stator
10.2.4 When the stator temperature has reached 70 °C, turn
before initial use of the viscometer. For those TBS Models (other than
on the motor while pushing the red bouncer button on the
Model 2100E) requiring bearing inspection, low bearing hysteresis and
console or gently holding the platform ball away from the
bearing cleanliness are also important to obtaining reliable data.
load-cell platen (see Note 2) by lightly pushing clockwise on
NOTE 11—Bearing hysteresis should be checked every few months and
the brass pulley post set into the motor turntable. (This is not
ifthevaluesofincreasinganddecreasingtorquearesignificantlydifferent,
thebearingshouldbecleanedandre-checkedbyhysteresismeasurements.
required or possible with Model 2100E.)
9.3 If the TBS viscometer has been turned off for some
NOTE 14—For TBS Models 500, 600, and SS, it is good practice to
period of time (>1 h), make sure the motor is off and slowly
always press on and hold the bouncer button, or otherwise push the
contact ball away from the load-cell platen before turning the motor on or
(;2 min) inject 50 mL of R-2400 into the stator while turning
off.Thisuseofthebouncerbuttonpreventstheinitialstart-uporshutdown
the rotor using the upper Siamese collet connecting the motor
surge of the motor from causing the contact ball to hammer on the platen
shaft and the drive wire slowly between the thumb and
of the sensitive load-cell.
forefinger.
NOTE 15—Sufficient warm-up time is important for consistency and
precision. Operating with R-2400 adds the effect of viscous heating to the
9.4 If the TBS Viscometer has been operating at 100 °C,
electrical heating of the stator and speeds the process.
proceed to Section 11 unless recalibration is desired.
10.2.5 When the temperature stabilizes at 100.0 °C 6
9.4.1 If recalibration is desired, proceed to 10.2.
0.2 °C, go to Section 11.
10. Calibration
10.3 If the TBS viscometer is already operating but at
temperatures higher than 100 °C, set the temperature control to
10.1 If the operating position of the rotor in the stator has
100.0 °C and slowly (;1 min) inject 50 mL of idling oil into
already been established in previous work at 100 °C, proceed
the stator through the fill tube. If using air cooling, turn the dry
to Section 12.
gasflow-meterknobontheconsoletomaximumflowrate(100
10.2 If the operating position of the rotor in the stator must
SCFH). If using liquid cooling, start circulation.
be established from a cold start for operation at 100 °C, follow
10.3.1 When the temperature reaches 100.0 °C 6 0.2 °C
the manufacturer’s instructions to find the rubbing contact
and while the motor is turning, slowly (;1 min) inject 50 mL
position of the rotor with the stator by rotating the upper
of Newtonian calibration oil, R-2400.
Siamese collet between the thumb and forefinger as the rotor is
10.4 Maintain appropriate air or liquid cooling rate.
slowly lowered by using the elevator wheel (see Note 12).
6 –1
NOTE 12—The indicator dial reading decreases when the rotor and
11. Setting the Rotor Position at 110 s Shear Rate –
platformareraisedandvice-versa.ExercisecareinusingtheTBSelevator
the Reciprocal Torque Intercept
wheel to move the rotor in the direction intended by the indicating arrow
NOTE16—Inalldatacollectedforthedeterminationofviscosity,torque
on top of the wheel (clockwise to simultaneously raise both the platform
andtemperature,equilibriumisnecessary.Normally,thisisreachedwithin
and rotor, counter clockwise to lower both).
5 min after injection of oil having a viscosity less than about 12 mPa·s
10.2.1 After finding the rubbing contact position, turn the
(cP) to 15 mPa·s (cP). However, with oils that are more viscous, the time
elevator wheel clockwise (see Note 12)to raise the platform toestablishequilibriummayextendto7 minor8 minat100 °C.Underall
circumstances, equilibrium is assumed within 10 min of injection, at
and the rotor by decreasing the depth indicator dial reading by
which point values should be taken and the next step in the method begun.
0.5 mm.
11.1 R-2400 Newtonian Oil—Establishthereciprocaltorque
10.2.2 After making sure that the MOTOR switch is in the
information for R-2400 Newtonian oil by turning on the
off position, turn on the POWER switch and permit the
strip-chart recorder and slowly (;1 min) injecting 50 mL of
electronic components of the console to warm up for a suitable
R-2400 calibration oil.
length of time according to the manufacturer’s instructions.
11.1.1 Press and hold the bouncer button, then turn off the
10.2.3 Set the console’s temperature controller to 100.0 °C
motor (see Note 14). Proceed to find rubbing contact of the
and permit the stator to begin warming up to that temperature.
rotor with the stator as described in 10.2.
Do not turn on the motor.
11.1.2 After finding the rubbing contact position, use the
NOTE 13—The viscosity of the oil decreases exponentially with
elevator to raise the platform and the rotor by ;0.15 mm to the
temperature and it is important that the motor not be started at higher
nearest exact whole tenth (0.100) millimetre value on the depth
viscosities than 20 mPa·s (cP) to 30 mPa·s (cP) to protect the wire drive
shaft. indicator dial (see Table 2, Example).
TABLE 2 Example of Torque/Height Data
Rotor (Platform) Position Example Torque, T Reciprocal Torque, 1/T
R-2400 NNR-10 R-2400 NNR-10
A
Rubbing Contact 14.176 mm ––––
A
Up ;0.15 mm to nearest 0.1 mm 14.000 mm value value 1/value 1/value
A
Up to 0.100 mm 13.900 mm value value 1/value 1/value
A
Up to 0.100 mm 13.800 mm value value 1/value 1/value
A
Up to 0.100 mm 13.700 mm value value 1/value 1/value
A
Up to 0.100 mm 13.600 mm value value 1/value 1/value
A
See Note 12 for relationship between rotor (platform) position and micrometer reading
D6616 − 21
NOTE 17—When the rotor is raised and lowered, the indicator dial
the series of reciprocal torque determinations. Do not use the
needle should be read as exactly as possible (to the third decimal place by
bouncer button again while establishing the reciprocal torque
estimatingbetweendialmarkings)ateachposition.Parallaxinreadingthe
values.
dialindicatorshouldbeavoidedbyplacingtheeyeatthesamelevelasthe
11.2.2 Repeat the rotor (platform) adjusting, torque-
dial. A magnifying glass can be further helpful.
collecting sequence in 11.1.2 through 11.1.9 using identical
11.1.3 While pushing the red bouncer button on the console
rotor (platform) positions. Record all values of rotor (platform)
turn motor on (see Note 14).
position, resultant torques, and reciprocal torque values (see
11.1.4 Holdtheredbouncerbuttoninthedepressedposition
Notes 17 and 18).
and adjust the torque readout to zero (0000 on the dial)
11.2.2.1 As in 11.1.9.1, linearly regress the rotor (platform)
according to the manufacturer’s instructions.
position versus reciprocal torque values collected in 11.2 for
11.1.5 When torque/temperature equilibrium has been the non-Newtonian reference oil, NNR-10. Record the slope,
reached (see Note 16) at this initial position, press the bouncer intercept, and correlation coefficient.
button briefly (see Note 2) and release. As soon as the 11.2.2.2 The value of R should be equal to or greater than
computer-simulated or actual strip-chart recorder again shows (≥) 0.999. If the value of R is acceptable, record and proceed to
constant torque/temperature traces (see Note 16), record the 11.3.
torque value given by the data recording equipment as well as
11.2.2.3 If the value of R is less than 0.999, repeat 11.2.1
the rotor (platform) position shown by the depth indicator dial. through 11.2.2.2 with particular attention to setting, reading,
and recording the values of platform position and torque. If the
11.1.6 Continue with, and complete 11.1.7 through 11.1.9.4
value of R is still less than 0.999, contact the manufacturer.
without using bouncer button again.
11.1.7 Use the elevator to move the rotor (platform) up
11.3 Determination of Reciprocal Torque Intersection Posi-
6 –1
exactly 0.100 mm (see Note 17 and Table 2).Again, record the
tion for 1·10 s Shear Rate:
rotor (platform) position and the indicated torque after torque/
11.3.1 Calculate and record the reciprocal torque value,
temperature equilibrium is achieved (see Note 16).
1/T, for the intersection point of the linear equations of 11.1
i
and 11.2 (see Note 19 and Fig. 5). This provides the experi-
11.1.8 Again raise the rotor (platform) progressively and
6 –1
mentally determined rotor operating position for 1·10 s shear
exactly 0.100 mm (see Note 17) three more times for a total of
rate.
five sets of decreasing values of indicated torque with increas-
ing rotor (platform) height as in Table 2 (see Example) and
NOTE 19—The linear equation obtained from 11.1 using Newtonian
record the torque and rotor height values.
reference oil R-2400 isH=m/T+b in which m is the slope and b the
intercept and H and 1/T are rotor height and reciprocal torque. The linear
NOTE 18—The full sequence required is shown in Table 2 and provides
equation obtained from 11.2 using reference oil NNR-10 isH'=n/T'+c
five sets of torque/height data for each of R-2400 and NNR-10.
in which n is the slope and c the intercept, and H' and 1/ T' are rotor height
and reciprocal torque at the intersection point H =H' as well as 1/T =
i i i
11.1.9 Calculate the reciprocals of the torque values col-
1/T'. Setting equation H =m/T+b=H'= n/T' + c: m/T + b = n/T + c
i i i
lected in 11.1 through 11.1.8 (see Table 2) for the Newtonian
and 1/T =(c-b)/(m-n) substituting 1/T=(c-b)/m-n) intoH=m/T+b H
i i
6 –1
reference oil R-2400.
= [m(c-b)/(m-n)] + b; the intersection height for 1·10 s .
11.1.9.1 Linearlyregresstherotorheight(platform)position
12. Calibration of TBS Rotor and Stator
versus the reciprocal torque values found for these rotor
heights. Record the slope, intercept, and correlation coefficient,
12.1 Set rotor position exactly to that indicated by 11.3.1
R, of this best line.
(see Note 17).
11.1.9.2 The value of R should be equal to or greater than
6 –1
12.2 Check Rotor Position at 1·10 s Shear Rate:
(≥) 0.999.
NOTE 20—Slow expansion of the rotor and stator after start up of the
11.1.9.3 If R is less than (<) 0.999, slowly (;1 min)
TBS viscometer may slightly change the originally determined position of
re-inject 50 mL of R-2400 and repeat 11.1.2 through 11.1.9.2
6 –1
the rotor at 1·10 s shear rate and it is prudent to recheck the rotor
using special care to set and record the exact values of height
position and to make slight adjustments, if necessary.
to the third decimal place on the depth indicator dial (see Note
12.2.1 Slowly (;1 min) inject 50 mL of Newtonian refer-
17). Recalculate the value of R.
ence oil, R-2400, and allow for torque/temperature equilibra-
11.1.9.4 IfthevalueofRisnowacceptable,proceedto11.2.
tion (see Note 16).Apply the bouncer button briefly, allow t
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: D6616 − 20a D6616 − 21
Standard Test Method for
Measuring Viscosity at High Shear Rate by Tapered Bearing
Simulator Viscometer at 100 °C
This standard is issued under the fixed designation D6616; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
6 –1
1.1 This test method covers the laboratory determination of the viscosity of engine oils at 100 °C and 1·10 s using the Tapered
Bearing Simulator (TBS) viscometer.
NOTE 1—This test method is similar to Test Method D4683 which uses the same TBS viscometer to measure high shear viscosity at 150 °C.
1.2 The Newtonian calibration oils used to establish this test method range from approximately 5 mPa·s (cP) to 12 mPa·s (cP) at
100 °C and either the manual or automated protocol was used by each participant in developing the precision statement. The
viscosity range of the test method at this temperature is from 1 mPa·s (cP) to above 25 mPa·s (cP), depending on the model of TBS.
6 –1
1.3 The non-Newtonian reference oil used to establish the shear rate of 1·10 s for this test method has a viscosity of
approximately 10 mPa·s at 100 °C.
1.4 Application to petroleum products other than engine oil has not been determined in preparing the viscometric information for
this test method.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. This
test method uses the milliPascal second (mPa·s) as the unit of viscosity. This unit is equivalent to the centiPoise (cP), which is
shown in parentheses.
1.6 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, health, and environmental practices and to determine the applicability
of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.07 on Flow Properties.
Current edition approved Sept. 1, 2020Jan. 1, 2021. Published October 2020January 2021. Originally approved in 2001. Last previous edition approved in 2020 as
D6616 – 20.D6616 – 20a. DOI: 10.1520/D6616-20A.10.1520/D6616-21.
Available from Tannas Co., 4800 James Savage Rd., Midland, MI 48642. This viscometer and associated equipment as listed in the research report was used to develop
the precision statement. To date, no other equipment has demonstrated, through ASTM International interlaboratory testing, the ability to meet the precision of this test. This
is not an endorsement or certification by ASTM International.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6616 − 21
2. Referenced Documents
2.1 ASTM Standards:
D4683 Test Method for Measuring Viscosity of New and Used Engine Oils at High Shear Rate and High Temperature by Tapered
Bearing Simulator Viscometer at 150 °C
D4741 Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer
4,5
2.2 Coordinating European Council (CEC) Standard:
CEC L-36-90 The Measurement of Lubricant Dynamic Viscosity under Conditions of High Shear
6,5
2.3 Energy Institute Standard:
IP 370 Test Method for the Measurement of Lubricant Dynamic Viscosity Under Conditions of High Shear Using the Ravenfield
Viscometer
3. Terminology
3.1 Definitions:
3.1.1 density, n—mass per unit volume at a specified temperature.volume.
3.1.1.1 Discussion—
For common fuel and lubricant applications, density at atmospheric pressure is assumed. However, high pressure can impact
density.
3.1.2 Newtonian oil or fluid, n—an oil or fluid that at a given temperature exhibits a constant viscosity at all shear rates or shear
stresses.
3.1.3 non-Newtonian oil or fluid, n—an oil or fluid that exhibits a viscosity that varies with changing shear stress or shear rate.
3.1.4 shear rate, n—velocity gradient perpendicular to the direction of flow.
3.1.5 shear stress, n—the force per unit area in the direction of the flow.
3.1.6 viscosity, n—the ratio between the applied shear stress and rate of shear which is sometimes called the coefficient of dynamic
viscosity and is a measure of the resistance to flow of the liquid.
3.1.6.1 apparent viscosity, n—the viscosity of a non-Newtonian fluid at a given shear rate or shear stress determined by this test
method.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 idling oil , n—an oxidatively stable Newtonian oil injected into the operating viscometer stator when the instrument is likely
to be held for periods of time greater than 30 min and up to two weeks at 100 °C. Use of this oil prevents stator deposits from
additives, which may decompose after longer exposure times in the operating viscometer and permits continuous operation of the
viscometer without need to shut the instrument off.
3.2.2 Newtonian Reference Oil , n—a specially blended Newtonian oil that has the same viscosity at 100 °C as the non-Newtonian
reference oil of 3.2.3.
3.2.3 non-Newtonian reference oil , n—a specially formulated non-Newtonian oil, identified as NNR-10, having a selected
6 –1
apparent viscosity at 1·10 s shear rate. The oil is used to establish an operating gap between the rotor and stator which will
6 –1
produce 1·10 s shear rate when the rotor height is adjusted to give a torque output equivalent to that of the special reference oil
described in 3.2.2.
3.2.4 reciprocal torque intersection, 1/T , n—the rotor position on the micrometer defined by the intersection of two straight lines
i
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from Coordinating European Council (CEC), Services provided by Kellen Europe, Avenue Jules Bordet 142 - 1140, Brussels, Belgium, http://www.cectests.org.
This test equipment is identical to that described in CEC L-36-90 (under the jurisdiction of the CEC Engine Lubricants Technical Committee) and IP 370 references CEC
L-36-90.
Available from Energy Institute, 61 New Cavendish St., London, W1G 7AR, U.K., http://www.energyinst.org.
D6616 − 21
generated by the reciprocal torque method using the Newtonian reference oil of 3.2.2 and non-Newtonian reference oil of 3.2.3.
Reciprocal torque versus rotor height measurements on both oils gives straight lines whose intersection, 1/T , establishes the
i
6 –1
desired rotor position for operation at 1·10 s shear rate.
3.2.5 reference Newtonian calibration oils , n—specially chosen Newtonian oils used to determine the viscosity-torque
relationship of the TBS viscometer at 100 °C from which the viscosity of an unknown oil is calculated.
3.2.6 rotor height (rotor position), n—the vertical position of the rotor relative to the stator and measured by the platform
micrometer.
3.2.6.1 stored rotor height (rotor position), n—the rotor position with the rotor 0.50 mm above the rubbing contact position (see
3.2.7) when the instrument is shut down.
3.2.7 rubbing contact position, n—the rotor height determined when the tapered rotor is lightly brought into contact with the
similarly tapered stator.
3.2.8 test oil, n—any oil for which the apparent viscosity is to be determined by this test method.
4. Summary of Test Method
4.1 A motor drives a tapered rotor closely fitted inside a matched tapered stator. Appropriate technique establishes operation of
6 –1
the viscometer to yield 1·10 s at a temperature of 100 °C at which point test oils are introduced into the gap between the spinning
rotor and stationary stator. The rotor exhibits a reactive torque to the viscous resistance of each test oil and the value of this torque
response is used to determine the apparent viscosity of the test oil at 100 °C.
5. Significance and Use
5.1 Viscosity at the shear rate and temperature of this test method is thought to be particularly representative of bearing conditions
in large medium speed reciprocating engines as well as automotive and heavy duty engines operating in this temperature regime.
5.2 The importance of viscosity under these conditions has been stressed in railroad specifications.
5.3 For other industry needs this method may also be run at 80 °C by using different crossover calibration oils available from the
manufacturer. No precision has been determined at this temperature. The equipment is also used at higher temperatures as shown
in Test Method D4683 and CEC L-36-90 (also referenced from IP 370).
6. Apparatus
6.1 Tapered Bearing Simulator Viscometers (TBS)—A viscometer consisting of a motor connected to a slightly tapered rotor that
fits into a matched stator. Several models of the TBS are in use. All of these are capable of analyzing test oils at 100 °C but earlier
models are more limited in their upper viscosity range.
6 –1
6.2 Different models of the tapered bearing simulator (TBS) have the following upper levels of operating viscosities at 1·10 s
shear rate:
6.2.1 Model Series 400 (similar to Fig. 1)—;14 mPa·s (cP), dual speed.
6.2.2 Model Series 500 (Fig. 1)—;16 mPa·s (cP) single speed.
6.2.3 Model Series 600 (Fig. 2)—;100 mPa·s (cP) (usually liquid cooled), dual speed.
6.2.4 Model Series SS (SuperShear) (similar to Fig. 1)—;20 mPa·s (cP), multi-speed.
6.2.5 Model Series 2100 E (Fig. 3)—;20 mPa·s (cP) (see Note 2), multi-speed.
NOTE 2—TBS Models 500, 600, and SS use a so-called bouncer to automate unloading and reloading the load cell just before taking a torque reading.
(All automated units apply the bouncer at the appropriate point of operation as part of their program.) If a bouncer is not on the TBS model used (Model
D6616 − 21
FIG. 1 Tapered Bearing Simulator Viscometer Model 500
FIG. 2 High Torque Tapered Bearing Simulator Viscometer Model 600
400), the effect is generated by placing the thumb on the brass weight pin and turning the turntable slightly in a clockwise direction and quickly releasing
the turntable. The bearingless Models 2100 E do not require unloading the cell since there is no turntable bearing.
D6616 − 21
FIG. 3 Multi-Speed Tapered Bearing Simulator Viscometer Model 2100E
6.3 Automated System for Calibration, Injection, and Data Analysis Programs—An automated program for the Tapered Bearing
Simulator, simulating the manual method has been used.
6.4 Console—The console shown in Fig. 4 is similar in Models 400, 500, and 600. Consoles for Series SS and 2100 E have
provisions for changing motor speed. All consoles contain the power source for the load cell, thermoregulator circuit, stator-heating
element, and motor. They also contain the circuitry for regulating and monitoring the temperature of the oil in the stator as well
as the amplifier and digital readout of the load cell.
FIG. 4 Control Console for Tapered Bearing Simulator Viscometer Models 400, 500, and 600
D6616 − 21
NOTE 3—The thermoregulator circuit of the TBS viscometers has evolved as improvements have been made in the solid-state temperature controller and
heater. To achieve the 5 min analysis time specified in this test method requires a late model solid-state controller with automatic reset coupled to a
thermo-foil stator heater with small heat inertia or a fast-responding thermoregulated liquid bath.
6.5 Cooling Systems—Two cooling systems are available for TBS viscometer work at 100 °C: forced air cooling and liquid bath
cooling. The stator housing is prepared for the former but must be modified for the latter according to directions from the
manufacturer.
6.6 Glass Syringe—A 50 mL glass syringe equipped with a Luer needle lock fits the tip of the filling tube for injection of test oil
into the test cell. Smaller glass and plastic syringes can be used if any air bubble in the fill tube caused by the exchange of syringes
is first pulled up into the next syringe to be used.
2 2
6.7 Filter Assembly—A unit made of a filter holder and nominal 10 μ filter is interposed between the syringe and the filling tube
to remove particles capable of damaging the rotor/stator cell.
6.8 Data Recording Equipment—Some form of recording the torque and temperature data produced by the tapered bearing
simulator is desired in order to (1) determine torque/temperature equilibrium and (2) determine the torque with sufficient precision
to calculate viscosity to the second decimal place. Early in the use of the TBS viscometer, a strip-chart recorder was used, later
an automated, computer-based recording system was developed with both a computer-simulated strip chart and with data digitally
recorded.
NOTE 4—Although the console has a torque indicator that can be used for determining viscosity, it has been found that the small oscillatory variation of
torque with time makes desirable the recording and analysis of the torque output more precise, particularly when determining torque equilibrium.
6.8.1 Strip-chart Recorder:
6.8.1.1 If a strip-chart recorder is used to record the torque and temperature output signals, use the manufacturer’s directions for
calibrating and setting up the strip chart for recording torque/temperature data (see Note 5). The torque reading must be in
milliVolts and the temperature in °C with a full-scale chart range of 20 °C to 120 °C.
6.8.1.2 Use a chart speed of 1 cm ⁄min for recording.
6.8.1.3 Set and, when necessary, reset, the strip chart torque voltage to that which will permit recording the torque as much as
possible on the upper two-thirds of the chart paper for maximum sensitivity.
6.8.1.4 Factor the resulting voltage values to calculate the correct values of torque.
NOTE 5—Although the digital information from the torque output meter on the viscometer console can be, and is, used for recording additional test
information, it is desirable to use a two-pen, strip-chart recorder or its computer equivalent since this provides a continuous torque/temperature record
of torque/temperature equilibrium necessary for precision in calibration and in calculating viscosity.
6.8.2 Computer Accumulation of Torque and Temperature Data—Computer recording of digital data can also be used for the test
method. Such programs should show data for both torque and stator temperature. Torque information should be capable of
permitting the calculation of viscosity to the second decimal place.
7. Materials
7.1 Reference Newtonian Calibration Oils, Newtonian oils of known dynamic viscosity at 100 °C. Table 1 shows the dynamic
viscosity values of five Newtonian oils used in developing the information for this test method.
7.2 Idling Oil—See 3.2.1 for information and use.
2 6 –1
7.3 Non-Newtonian Reference Oil, essential in setting the rotor/stator gap to 1·10 s shear rate. The nominal level of apparent
viscosity of non-Newtonian reference oil, NNR-10 used in applying this test method is given in Table 1.
7.4 Polar Solvent, such as dimethyl sulfoxide is used to dissolve any deposits on the rotor/stator surfaces after extended use.
D6616 − 21
TABLE 1 Reference Oil Viscosities at 100.0°C100.0 °C
A
Reference Oil Characteristic Nominal Viscosities
6 –1
mPa·s at 1·10 s
R-2200 Newtonian ;3
R-2300 Newtonian ;5
R-2350 Newtonian ;7
R-2400 Newtonian ;10
R-2450 Newtonian ;12
B
NNR-10 Non-Newtonian ;10
A
Contact supplier for certified value of Reference Oil.
B 6 –1
Special reference oil closely equivalent to R-2400 at a value of 1·10 s shear
rate.
7.5 Source of moderate pressure (<100 PSI) dry air or nitrogen.
6 –1
NOTE 6—Depending on room temperatures, higher torque levels at 100 °C and 1·10 s may require air or other gas cooling. Use of dry gas is required
(to keep moisture from entering the stator housing).
8. Sampling
8.1 Fifty millilitres of a representative sample of fresh or used test oil is placed in a 50 mL syringe equipped with attached filter
holder and 10 μ filter disk in preparation for injection into the TBS viscometer.
NOTE 7—It is important to always use a filter and filter disk to prevent larger particles from entering the rotor-stator gap. However, it is also important
to note that the TBS viscometer will work with heavily particle laden used oils as long as they are passed through the 10 μ filter.
9. Preparation of Apparatus
9.1 Set up stator cooling method, air or liquid, according to the manufacturer’s directions.
NOTE 8—When analyzing relatively viscous oils, stator cooling is necessary. This is particularly the case at lower operating temperatures such as 100 °C
where simple radiation from the stator through the stator housing is not sufficient to carry away the heat generated by viscous resistance to shear.
9.1.1 Air Cooling—Connect cooling air tubing to the ports on the stator housing and the back of the console following directions
given by the manufacturer in the Owner’s Manual. This will permit use of the flow meter on the left side of the console to adjust
the cooling-air flow rate.
9.1.1.1 Set the airflow rate at 100 SCFH.
NOTE 9—Once airflow rate has been set, it is important that this level be maintained throughout calibration and operation. If desired, the air may be passed
through a copper coil in a chilling bath containing water, ice, or dry ice, as necessary, to obtain desired stator temperature. The cooling level must be
kept constant.
9.1.2 Liquid Cooling—Connect liquid cooling bath tubing from bath pump to the stator housing and the back of the console using
insulated tubing according to the manufacturer’s directions.
9.2 If some days or weeks have elapsed since last use of the TBS viscometer, follow the manufacturer’s instructions regarding
set-up and alignment of the rotor in the stator, checking the accuracy of the RTD and, if necessary, adjusting to 100.0 °C. Shut the
power off and go to 9.3.
NOTE 10—Directions for preparation of the tapered bearing simulator viscometer and console are supplied with the equipment. One of the most important
directions to be followed is the alignment of the rotor and stator before initial use of the viscometer. For those TBS Models (other than Model 2100E)
requiring bearing inspection, low bearing hysteresis and bearing cleanliness are also important to obtaining reliable data.
NOTE 11—Bearing hysteresis should be checked every few months and if the values of increasing and decreasing torque are significantly different, the
bearing should be cleaned and re-checked by hysteresis measurements.
D6616 − 21
9.3 If the TBS viscometer has been turned off for some period of time (>1 h), make sure the motor is off and slowly (;2 min)
inject 50 mL of R-2400 into the stator while turning the rotor using the upper Siamese collet connecting the motor shaft and the
drive wire slowly between the thumb and forefinger.
9.4 If the TBS Viscometer has been operating at 100 °C, proceed to Section 11 unless recalibration is desired.
9.4.1 If recalibration is desired, proceed to 10.2.
10. Calibration
10.1 If the operating position of the rotor in the stator has already been established in previous work at 100 °C, proceed to Section
12.
10.2 If the operating position of the rotor in the stator must be established from a cold start for operation at 100 °C, follow the
manufacturer’s instructions to find the rubbing contact position of the rotor with the stator by rotating the upper Siamese collet
between the thumb and forefinger as the rotor is slowly lowered by using the elevator wheel (see Note 12).
NOTE 12—The indicator dial reading decreases when the rotor and platform are raised and vice-versa. Exercise care in using the TBS elevator wheel to
move the rotor in the direction intended by the indicating arrow on top of the wheel (clockwise to simultaneously raise both the platform and rotor, counter
clockwise to lower both).
10.2.1 After finding the rubbing contact position, turn the elevator wheel clockwise (see Note 12) to raise the platform and the
rotor by decreasing the depth indicator dial reading by 0.5 mm.
10.2.2 After making sure that the MOTOR switch is in the off position, turn on the POWER switch and permit the electronic
components of the console to warm up for a suitable length of time according to the manufacturer’s instructions.
10.2.3 Set the console’s temperature controller to 100.0 °C and permit the stator to begin warming up to that temperature. Do not
turn on the motor.
NOTE 13—The viscosity of the oil decreases exponentially with temperature and it is important that the motor not be started at higher viscosities than
20 mPa·s (cP) to 30 mPa·s (cP) to protect the wire drive shaft.
10.2.4 When the stator temperature has reached 70 °C, turn on the motor while pushing the red bouncer button on the console or
gently holding the platform ball away from the load-cell platen (see Note 2) by lightly pushing clockwise on the brass pulley post
set into the motor turntable. (This is not required or possible with Model 2100E.)
NOTE 14—For TBS Models 500, 600, and SS, it is good practice to always press on and hold the bouncer button, or otherwise push the contact ball away
from the load-cell platen before turning the motor on or off. This use of the bouncer button prevents the initial start-up or shutdown surge of the motor
from causing the contact ball to hammer on the platen of the sensitive load-cell.
NOTE 15—Sufficient warm-up time is important for consistency and precision. Operating with R-2400 adds the effect of viscous heating to the electrical
heating of the stator and speeds the process.
10.2.5 When the temperature stabilizes at 100.0 °C 6 0.2 °C, go to Section 11.
10.3 If the TBS viscometer is already operating but at temperatures higher than 100 °C, set the temperature control to 100.0 °C
and slowly (;1 min) inject 50 mL of idling oil into the stator through the fill tube. If using air cooling, turn the dry gas flow-meter
knob on the console to maximum flow rate (100 SCFH). If using liquid cooling, start circulation.
10.3.1 When the temperature reaches 100.0 °C 6 0.2 °C and while the motor is turning, slowly (;1 min) inject 50 mL of
Newtonian calibration oil, R-2400.
10.4 Maintain appropriate air or liquid cooling rate.
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6 –1
11. Setting the Rotor Position at 1•10 s Shear Rate – the Reciprocal Torque Intercept
NOTE 16—In all data collected for the determination of viscosity, torque and temperature, equilibrium is necessary. Normally, this is reached within 5 min
after injection of oil having a viscosity less than about 12 mPa·s (cP) to 15 mPa·s (cP). However, with oils that are more viscous, the time to establish
equilibrium may extend to 7 min or 8 min at 100 °C. Under all circumstances, equilibrium is assumed within 10 min of injection, at which point values
should be taken and the next step in the method begun.
11.1 R-2400 Newtonian Oil—Establish the reciprocal torque information for R-2400 Newtonian oil by turning on the strip-chart
recorder and slowly (;1 min) injecting 50 mL of R-2400 calibration oil.
11.1.1 Press and hold the bouncer button, then turn off the motor (see Note 14). Proceed to find rubbing contact of the rotor with
the stator as described in 10.2.
11.1.2 After finding the rubbing contact position, use the elevator to raise the platform and the rotor by ;0.15 mm to the nearest
exact whole tenth (0.100) millimetre value on the depth indicator dial (see Table 2, Example).
NOTE 17—When the rotor is raised and lowered, the indicator dial needle should be read as exactly as possible (to the third decimal place by estimating
between dial markings) at each position. Parallax in reading the dial indicator should be avoided by placing the eye at the same level as the dial. A
magnifying glass can be further helpful.
11.1.3 While pushing the red bouncer button on the console turn motor on (see Note 14).
11.1.4 Hold the red bouncer button in the depressed position and adjust the torque readout to zero (0000 on the dial) according
to the manufacturer’s instructions.
11.1.5 When torque/temperature equilibrium has been reached (see Note 16) at this initial position, press the bouncer button
briefly (see Note 2) and release. As soon as the computer-simulated or actual strip-chart recorder again shows constant
torque/temperature traces (see Note 16), record the torque value given by the data recording equipment as well as the rotor
(platform) position shown by the depth indicator dial.
11.1.6 Continue with, and complete 11.1.7 through 11.1.9.4 without using bouncer button again.
11.1.7 Use the elevator to move the rotor (platform) up exactly 0.100 mm (see Note 17 and Table 2). Again, record the rotor
(platform) position and the indicated torque after torque/temperature equilibrium is achieved (see Note 16).
11.1.8 Again raise the rotor (platform) progressively and exactly 0.100 mm (see Note 17) three more times for a total of five sets
of decreasing values of indicated torque with increasing rotor (platform) height as in Table 2 (see Example) and record the torque
and rotor height values.
NOTE 18—The full sequence required is shown in Table 2 and provides five sets of torque/height data for each of R-2400 and NNR-10.
11.1.9 Calculate the reciprocals of the torque values collected in 11.1 through 11.1.8 (see Table 2) for the Newtonian reference
oil R-2400.
11.1.9.1 Linearly regress the rotor height (platform) position versus the reciprocal torque values found for these rotor heights.
Record the slope, intercept, and correlation coefficient, R, of this best line.
11.1.9.2 The value of R should be equal to or greater than (≥) 0.999.
TABLE 2 Example of Torque/Height Data
Rotor (Platform) Position Example Torque, T Reciprocal Torque, 1/T
R-2400 NNR-10 R-2400 NNR-10
A
Rubbing Contact 14.176 mm – – – –
A
Up ;0.15 mm to nearest 0.1 mm 14.000 mm value value 1/value 1/value
A
Up to 0.100 mm 13.900 mm value value 1/value 1/value
A
Up to 0.100 mm 13.800 mm value value 1/value 1/value
A
Up to 0.100 mm 13.700 mm value value 1/value 1/value
A
Up to 0.100 mm 13.600 mm value value 1/value 1/value
A
See Note 12 for relationship between rotor (platform) position and micrometer reading
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11.1.9.3 If R is less than (<) 0.999, slowly (;1 min) re-inject 50 mL of R-2400 and repeat 11.1.2 through 11.1.9.2 using special
care to set and record the exact values of height to the third decimal place on the depth indicator dial (see Note 17). Recalculate
the value of R.
11.1.9.4 If the value of R is now acceptable, proceed to 11.2. If the value of R is still not high enough, contact the manufacturer
of the TBS.
11.2 Non-Newtonian Reference Oil, NNR-10—Establish the reciprocal torque information for the non-Newtonian reference oil,
NNR-10 by slowly (;1 min) injecting 50 mL of non-Newtonian reference oil NNR-10 and setting the rotor (platform) height to
the exact initial position previously used for the Newtonian Reference oil, R-2400 in 11.1.2 (see Note 17).
11.2.1 Establish temperature/torque equilibrium, then record the rotor (platform) position indicated by the depth indicator dial and
use the bouncer button once only to initiate the series of reciprocal torque determinations. Do not use the bouncer button again
while establishing the reciprocal torque values.
11.2.2 Repeat the rotor (platform) adjusting, torque-collecting sequence in 11.1.2 through 11.1.9 using identical rotor (platform)
positions. Record all values of rotor (platform) position, resultant torques, and reciprocal torque values (see Notes 17 and 18).
11.2.2.1 As in 11.1.9.1, linearly regress the rotor (platform) position versus reciprocal torque values collected in 11.2 for the
non-Newtonian reference oil, NNR-10. Record the slope, intercept, and correlation coefficient.
11.2.2.2 The value of R should be equal to or greater than (≥) 0.999. If the value of R is acceptable, record and proceed to 11.3.
11.2.2.3 If the value of R is less than 0.999, repeat 11.2.1 through 11.2.2.2 with particular attention to setting, reading, and
recording the values of platform position and torque. If the value of R is still less than 0.999, contact the manufacturer.
6 –1
11.3 Determination of Reciprocal Torque Intersection Position for 1·10 s Shear Rate:
11.3.1 Calculate and record the reciprocal torque value, 1/T , for the intersection point of the linear equations of 11.1 and 11.2 (see
i
6 –1
Note 19 and Fig. 5). This provides the experimentally determined rotor operating position for 1·10 s shear rate.
NOTE 19—The linear equation obtained from 11.1 using Newtonian reference oil R-2400 is H = m/T + b in which m is the slope and b the intercept and
H and 1/T are rotor height and reciprocal torque. The linear equation obtained from 11.2 using reference oil NNR-10 is H' = n/T' + c in which n is the
slope and c the intercept, and H' and 1/ T' are rotor height and reciprocal torque at the intersection point H = H ' as well as 1/T = 1/T '. Setting equation
i i i i
FIG. 5 Reciprocal Torque Intercept of R-2400 and NNR-10 for
...