ASTM D5133-20a

Standard Test Method for Low Temperature, Low Shear Rate, Viscosity/Temperature Dependence of Lubricating Oils Using a Temperature-Scanning Technique

SIGNIFICANCE AND USE
5.1 Significance of Low-Temperature, Low Shear Rate, Engine Oil Rheology—The low-temperature, low-shear viscometric behavior of an engine oil determines whether the oil will flow to the sump inlet screen, then to the oil pump, then to the sites in the engine requiring lubrication in sufficient quantity to prevent engine damage immediately or ultimately after cold temperature starting.  
5.1.1 Two forms of flow problems have been identified,4 flow-limited and air-binding behavior. The first form of flow restriction, flow-limited behavior, is associated with the oil's viscosity; the second, air-binding behavior, is associated with gelation.  
5.2 Significance of the Test Method—The temperature-scanning technique employed by this test method was designed to determine the susceptibility of the engine oil to flow-limited and air-binding response to slow cooling conditions by providing continuous information on the rheological condition of the oil over the temperature range of use.4,5,7 In this way, both viscometric and gelation response are obtained in one test.
Note 1: This test method is one of three related to pumpability related problems. Measurement of low-temperature viscosity by the two other pumpability Test Methods D3829 and D4684, hold the sample in a quiescent state and generate the apparent viscosity of the sample at shear rates ranging up to 15 sec-1 and shear stresses up to 525 Pa at a previously selected temperature. Such difference in test parameters (shear rate, shear stress, sample motion, temperature scanning, and so forth) can lead to differences in the measured apparent viscosity among these test methods with some test oils, particularly when other rheological factors associated with gelation are present. In addition, the three methods differ considerably in cooling rates.  
5.3 Gelation Index and Gelation Index Temperature—This test method has been further developed to yield parameters called the Gelation Index and Gelation Index temperature. T...
SCOPE
1.1 This test method covers the measurement of the apparent viscosity of engine oil at low temperatures.  
1.2 A shear rate of approximately 0.2 s-1 is produced at shear stresses below 100 Pa. Apparent viscosity is measured continuously as the sample is cooled at a rate of 1 °C/h over the range −5 °C to −40 °C, or to the temperature at which the viscosity exceeds 40 000 mPa·s (cP).  
1.3 The measurements resulting from this test method are viscosity, the maximum rate of viscosity increase (Gelation Index), and the temperature at which the Gelation Index occurs.  
1.4 Applicability to petroleum products other than engine oils has not been determined in preparing 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.  
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 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-May-2020
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.07 - Flow Properties

Relations

• Replaces: ASTM D5133-20 - Standard Test Method for Low Temperature, Low Shear Rate, Viscosity/Temperature Dependence of Lubricating Oils Using a Temperature-Scanning Technique
• Effective Date: 01-Jun-2020
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D341-20 - Standard Practice for Viscosity-Temperature Equations and Charts for Liquid Petroleum or Hydrocarbon Products
• Effective Date: 01-May-2020
• Refers: ASTM D341-20e1 - Standard Practice for Viscosity-Temperature Equations and Charts for Liquid Petroleum or Hydrocarbon Products
• Effective Date: 01-May-2020
• Refers: ASTM E644-11(2019) - Standard Test Methods for Testing Industrial Resistance Thermometers
• Effective Date: 01-Nov-2019
• Refers: ASTM D3829-18 - Standard Test Method for Predicting the Borderline Pumping Temperature of Engine Oil
• Effective Date: 01-Jun-2018
• Refers: ASTM D6299-17b - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Dec-2017
• Refers: ASTM D6299-17a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Nov-2017
• Refers: ASTM D341-17 - Standard Practice for Viscosity-Temperature Charts for Liquid Petroleum Products
• Effective Date: 01-Jul-2017
• Refers: ASTM D3829-17 - Standard Test Method for Predicting the Borderline Pumping Temperature of Engine Oil
• Effective Date: 01-May-2017
• Refers: ASTM D6299-17 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Jan-2017
• Refers: ASTM D7962-16 - Standard Practice for Determination of Minimum Immersion Depth and Assessment of Temperature Sensor Measurement Drift
• Effective Date: 01-Dec-2016
• Refers: ASTM D7962-15a - Standard Practice for Determination of Minimum Immersion Depth and Assessment of Temperature Sensor Measurement Drift
• Effective Date: 01-Dec-2015
• Refers: ASTM D341-09(2015) - Standard Practice for Viscosity-Temperature Charts for Liquid Petroleum Products
• Effective Date: 01-Jun-2015
• Refers: ASTM D7962-15 - Standard Practice for Determination of Minimum Immersion Depth and Assessment of Temperature Sensor Measurement Drift
• Effective Date: 01-Apr-2015

Overview

ASTM D5133-20a is the Standard Test Method for Low Temperature, Low Shear Rate, Viscosity/Temperature Dependence of Lubricating Oils Using a Temperature-Scanning Technique. Developed by ASTM, this standard defines procedures for evaluating the flow properties of engine oils under low temperature and low shear rate conditions. The main objective is to determine whether an engine oil can adequately flow throughout critical engine components at cold start-up and prevent engine damage caused by flow-limited or gelation issues.

This method provides continuous measurement of the apparent viscosity as the oil is gradually cooled, offering key insights into both viscous and gelation behavior. This information is valuable for manufacturers, formulators, and quality assurance professionals concerned with engine oil pumpability and cold-weather performance.

Key Topics

• Low Temperature Viscosity Measurement
  The standard covers the methodology for measuring the apparent viscosity of engine oils at temperatures from -5°C to -40°C, using a constant cooling rate of 1°C per hour.

• Shear Rate and Shear Stress
  The test simulates a shear rate of approximately 0.2 s⁻¹ and shear stresses under 100 Pa, reflecting the operating conditions experienced during engine cold starts.

• Gelation Index and Gelation Index Temperature
  The procedure yields important parameters such as the Gelation Index (the maximum rate of viscosity increase) and the temperature at which it occurs, helping to identify oils prone to gel formation that can hinder flow.

• Flow Limitation and Air-Binding
  The method distinguishes between flow-limited behavior (primarily viscosity-related) and air-binding behavior (associated with gelation), both of which may impede oil delivery at low temperatures.

• Temperature-Scanning Technique
  Unlike static tests, this method measures viscosity continuously as the temperature decreases, providing a detailed profile of how the oil’s flow properties evolve.

Applications

• Engine Oil Development and Quality Assurance
  Oil formulators use ASTM D5133-20a to assess and compare the low-temperature pumpability and flow performance of lubricating oils. The standard helps ensure that oils will meet manufacturers’ requirements for reliable cold-weather operation.

• Specification Compliance
  OEMs (Original Equipment Manufacturers) and lubricant suppliers employ this test method to verify that engine oils meet specified pumpability limits and cold start performance criteria.

• Research and Development
  The data generated-viscosity curves, Gelation Indexes, and critical temperatures-are essential for the study of oil formulations designed for improved winter performance and for investigating the causes of oil gelation.

• Troubleshooting and Failure Analysis
  Engineers use the results to diagnose issues related to oil flow restrictions, such as insufficient oil reaching engine components during cold starts, which can lead to wear or damage.

Related Standards

• ASTM D3829: Test Method for Predicting the Borderline Pumping Temperature of Engine Oil
• ASTM D4684: Test Method for Determination of Yield Stress and Apparent Viscosity of Engine Oils at Low Temperature
• ASTM D341: Practice for Viscosity-Temperature Equations and Charts for Liquid Petroleum or Hydrocarbon Products
• ASTM D6299: Practice for Applying Statistical Quality Assurance for Analytical Measurement Systems
• ASTM D7962 and ASTM E644: Standards for temperature measurement and thermometer calibration

Summary

ASTM D5133-20a is a critical standard for evaluating the low-temperature flow characteristics and viscosity behavior of engine oils. Its continuous, temperature-scanning technique provides insights necessary for ensuring proper oil pumpability and protection during cold weather. By adhering to this standard, manufacturers and quality managers can better predict oil performance, optimize formulations, and meet industry and OEM requirements for engine oil quality and reliability.

Keywords: ASTM D5133, low temperature viscosity, lubricating oil pumpability, Gelation Index, engine oil rheology, cold start, oil gelation, viscosity measurement, lubricant testing standards.

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: D5133 − 20a
Standard Test Method for
Low Temperature, Low Shear Rate, Viscosity/Temperature
Dependence of Lubricating Oils Using a Temperature-
Scanning Technique
This standard is issued under the fixed designation D5133; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the measurement of the appar-
D341Practice for Viscosity-Temperature Equations and
ent viscosity of engine oil at low temperatures.
Charts for Liquid Petroleum or Hydrocarbon Products
-1
1.2 A shear rate of approximately 0.2s is produced at
D3829Test Method for Predicting the Borderline Pumping
shear stresses below 100Pa. Apparent viscosity is measured
Temperature of Engine Oil
continuously as the sample is cooled at a rate of 1°C⁄h over
D4684Test Method for Determination of Yield Stress and
the range −5°C to −40°C, or to the temperature at which the
Apparent Viscosity of Engine Oils at Low Temperature
viscosity exceeds 40000mPa·s (cP).
D6299Practice for Applying Statistical Quality Assurance
and Control Charting Techniques to Evaluate Analytical
1.3 The measurements resulting from this test method are
Measurement System Performance
viscosity, the maximum rate of viscosity increase (Gelation
D7962Practice for Determination of Minimum Immersion
Index), and the temperature at which the Gelation Index
Depth and Assessment of Temperature Sensor Measure-
occurs.
ment Drift
1.4 Applicability to petroleum products other than engine
E644Test Methods for Testing Industrial Resistance Ther-
oils has not been determined in preparing this test method.
mometers
1.5 The values stated in SI units are to be regarded as
3. Terminology
standard. No other units of measurement are included in this
3.1 Definitions:
standard.
3.1.1 apparent viscosity, n—theviscosityobtainedbyuseof
1.6 This standard does not purport to address all of the
this test method.
safety concerns, if any, associated with its use. It is the
3.1.1.1 Discussion—See3.1.7fordefinitionofviscosityand
responsibility of the user of this standard to establish appro-
units.
priate safety, health, and environmental practices and deter-
3.1.2 digital contact thermometer (DCT), n—an electronic
mine the applicability of regulatory limitations prior to use.
device consisting of a digital display and associated tempera-
1.7 This international standard was developed in accor-
ture sensing probe.
dance with internationally recognized principles on standard-
3.1.2.1 Discussion—This device consists of a temperature
ization established in the Decision on Principles for the
sensor connected to a measuring instrument; this instrument
Development of International Standards, Guides and Recom-
measures the temperature-dependent quantity of the sensor,
mendations issued by the World Trade Organization Technical
computes the temperature from the measured quantity, and
Barriers to Trade (TBT) Committee.
provides a digital output. This digital output goes to a digital
display or recording device, or both, that may be internal or
external to the device.
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2020. Published June 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1990. Last previous edition approved in 2020 as D5133–20. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D5133-20A. the ASTM website.
*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
D5133 − 20a
3.1.2.2 Discussion—The devices are often referred to as record and analyze torque output from the viscometer drive
“digitalthermometers,”howeverthetermincludesdevicesthat module and to render this information into tabular data and
sense temperature by means other than being in physical plotted relationships.
contact with the media. 3.2.4.1 analog-to-digital (A-D) converter, n—a device for
3.1.2.3 Discussion—PET is an acronym for portable elec- converting continuously produced electrical signals into dis-
crete numerical values capable of being analyzed by computer
tronic thermometers, a subset of digital contact thermometers
technology.
(DCT).
3.2.5 critical pumpability temperature, n—the temperature
3.1.3 Newtonian oil, n—an oil or fluid that at a given
in the programmable cooling bath at which an oil reaches a
temperature exhibits a constant viscosity at all shear rates or
chosen critical pumpability viscosity (see 3.2.6).
shear stresses.
3.2.6 critical pumpability viscosity, n—thatapparentviscos-
3.1.4 non-Newtonian oil, n—an oil or fluid that at a given
ity believed to cause pumpability problems in an engine. This
temperatureexhibitsaviscositythatvarieswithchangingshear
apparent viscosity is chosen to test an oil for its critical
stress or shear rate.
pumpability temperature.
3.1.5 shear rate, n—velocity gradient perpendicular to the
3.2.7 flow-limited oils, n—those oils whose borderline
direction of flow.
pumping temperatures are determined by viscous flow.
3.1.5.1 Discussion—The SI unit for shear rate is the recip-
-1
3.2.8 gelation, n—a rheological condition of an oil charac-
rocal second (1/s; also s ).
terized by a marked increase in the flow resistance over and
3.1.6 shear stress, n—force per unit area in the direction of
above the normal exponential increase of viscosity with
flow.
decreasingtemperature,particularlyatlowershearstressesand
3.1.6.1 Discussion—TheSIunitforshearstressisthePascal
temperatures.
(Pa).
3.2.8.1 Discussion—Gelation has been attributed to a pro-
3.1.7 viscosity, n—the ratio between the applied shear stress
cess of nucleation and crystallization of components of the
and rate of shear which is sometimes called the coefficient of
engine oil and the formation of a structure.
dynamic viscosity and is a measure of the resistance to flow of
3.2.9 Gelation Index, n—the maximum value of the incre-
the liquid.
mental ratio
3.1.7.1 Discussion—Mathematically expressed:
2 log logη 2 log logη #/ log T 2 log T (2)
@~ ! ~ ! ~ !
1 2 1 2
viscosity 5 shearstress/shearrateor, symbolically, η 5 τ/γ˙ (1)
(in which η is dynamic viscosity and T is in degrees Kel-
in which the symbols in the second portion of Eq 1 are
vin) over the temperature range scanned when the incremen-
defined by the terms in the first portion of the equation.
tal decrease in temperature is 1 K.
The SI unit for viscosity used herein is milliPascal sec-
3.2.9.1 Discussion—The technique of deriving Gelation In-
onds (mPa·s).
dex was first developed and practiced collecting information
3.2 Definitions of Terms Specific to This Standard: from a strip-chart recording and applying the empirical
MacCoull-Walther-Wright equation (Test Method D341). For
3.2.1 air-binding oils—those engine oils whose borderline
further information, see Appendix X1.
pumping temperatures are determined by a combination of
gelation and viscous flow.
3.2.10 Gelation Index reference oils, n—non-Newtonian
oils chosen to give certain levels of Gelation Index as a check
3.2.2 borderline pumping temperature, n—that temperature
on instrument performance.
at which an engine oil may have such poor flow characteristics
that the engine oil pump may not be capable of supplying
3.2.11 Gelation Index temperature, n—the temperature (t
sufficient lubricant to the engine.
inEq2)indegreesCelsiusatwhichtheGelationIndexoccurs.
3.2.3 calibration oil, n—Newtonianoilsdevelopedandused
3.2.12 programmable cooling bath, n—aliquidordryblock
to calibrate the viscometer drive module over the viscosity
(referredtoasdirectcool)bathhavingatemperaturecontroller
range required for this test method.
capable of being programmed to run the calibration and the
3.2.3.1 Discussion—these calibration oils are specially
analysis portions of the test method within the temperature
blended to give sufficient sensitivity and range for the special tolerances listed.
viscometer head used.
3.2.13 temperature controller, n—a programmable device
3.2.4 computer-programmed automated analysis, n—use of which, when properly programmed, ramps the temperature
modern techniques for acquiring analog data, converting these upward or downward at a chosen rate or series of steps while
to digital values and using this information to automatically simultaneously controlling temperature excursions.
3 4
The sole source of supply of the equipment and materials known to the Symposium on Low Temperature Lubricant Rheology Measurement and Rel-
committee at this time is Tannas Co., 4800 James Savage Rd., Midland, MI 48642. evance to Engine Operation, ASTM STP 1143, Rhodes, R. B., ed., ASTM, 1992.
If you are aware of alternative suppliers, please provide this information toASTM Selby, T.W., “The Use of the Scanning Brookfield Technique to Study the
International Headquarters. Your comments will receive careful consideration at a Critical Degree of Gelation of Lubricants at Low Temperatures”, SAE Paper
meeting of the responsible technical committee, which you may attend. 910746, Society of Automotive Engineers, 1991.
D5133 − 20a
3.2.13.1 calibration program, n—a program to run the 3.2.17 test oil, n—any oil for which apparent viscosity is to
required series of temperatures at which the torque values be determined using the procedure described by this test
necessary to calibrate the viscometer drive module are col- method.
lected and analyzed.
3.2.18 viscometer drive module, n—the rotor drive and
3.2.13.2 hold program, n—a program to reach and hold the
torque-sensing component of a rotational viscometer.
programmable cooling bath at −5°C.
3.2.19 viscometer module support, n—a part of the test cell
3.2.13.3 test program, n—a program to run the test oil
alignment device supporting the viscometer drive module.
analysis at 1°C⁄h temperature decrease.
3.2.14 test cell, n—the combination of the rotor and stator.
4. Summary of Test Method
Critical elements of the test cell are sketched in Fig. 1.
4.1 After preheating approximately 20mL of the test oil in
aglassstatorat90°Cfor1.5hto2.0h,thetestcellcontaining
the test oil is attached to a suitable viscometer drive module
andthetestcellimmersedinaprogrammablecoolingbathand
cooled at 1°C⁄h over the temperature range of −5°C to
−40°C. Data from the viscometer drive module is collected
and fed to a computerized data assimilation program to
determine the Gelation Index, Gelation Index temperature, and
Critical Pumpability temperature for a selected viscosity such
as 30000mPa·s or 40000mPa·s (cP).
5. Significance and Use
5.1 Significance of Low-Temperature, Low Shear Rate, En-
gine Oil Rheology—Thelow-temperature,low-shearviscomet-
ric behavior of an engine oil determines whether the oil will
flow to the sump inlet screen, then to the oil pump, then to the
sitesintheenginerequiringlubricationinsufficientquantityto
prevent engine damage immediately or ultimately after cold
temperature starting.
5.1.1 Two forms of flow problems have been identified,
flow-limited and air-binding behavior. The first form of flow
restriction, flow-limited behavior, is associated with the oil’s
viscosity; the second, air-binding behavior, is associated with
gelation.
FIG. 1 Test Cell
5.2 Significance of the Test Method—The temperature-
scanningtechniqueemployedbythistestmethodwasdesigned
to determine the susceptibility of the engine oil to flow-limited
3.2.14.1 rotor, n—a titanium rotor sized to give a compro-
andair-bindingresponsetoslowcoolingconditionsbyprovid-
mise of sensitivity and range to the determination of viscosity
ing continuous information on the rheological condition of the
and gelation using this test method.
4,5,7
oil over the temperature range of use. In this way, both
(1) stator, n—a precision-bore borosilicate glass or stain-
viscometric and gelation response are obtained in one test.
less steel tube, to which a measured amount of oil is added for
NOTE1—Thistestmethodisoneofthreerelatedtopumpabilityrelated
the test and within which the specially-made rotor turns.
problems. Measurement of low-temperature viscosity by the two other
(2) stator collar, n—a clamp for the stator which also
pumpability Test Methods D3829 and D4684, hold the sample in a
positions it on the test cell alignment device.
quiescent state and generate the apparent viscosity of the sample at shear
-1
3.2.15 sample preheater, n—a water bath, air bath or oven,
ratesrangingupto15sec andshearstressesupto525Paatapreviously
ordrybath(integratedorseparate)toheatthesamplesfor1.5h
selected temperature. Such difference in test parameters (shear rate, shear
stress, sample motion, temperature scanning, and so forth) can lead to
to 2.0h at 90°C 6 2°C before testing.
differences in the measured apparent viscosity among these test methods
3.2.16 test cell alignment device , n—a special device used
with some test oils, particularly when other rheological factors associated
to support the viscometer drive module while maintaining the
with gelation are present. In addition, the three methods differ consider-
ably in cooling rates.
stator and the rotor coaxial and vertical in regard to the
viscometer driveshaft. Later designs permit dry gas into the
5.3 Gelation Index and Gelation Index Temperature—This
cell to prevent moisture and frost buildup.
test method has been further developed to yield parameters
called the Gelation Index and Gelation Index temperature.The
The test cell alignment device is covered by patents. Interested parties are
invited to submit information regarding the identification of alternatives to this Shaub,H.,“AHistoryofASTMAccomplishmentsinLowTemperatureEngine
patented item to ASTM International Headquarters. Your comments will receive Oil Rheology,” Symposium on Low Temperature Lubricant Rheology Measurement
careful consideration at a meeting of the responsible technical committee, which and Relevance to Engine Operation, ASTM STP 1143, Rhodes, R. B., ed., ASTM,
you may attend. 1992, pp. 1–19.
D5133 − 20a
first parameter is a measure of the maximum rate of torque 6.5 Programmable Liquid or Scanning Brookfield Tech-
increasecausedbytherheologicalresponseoftheoilastheoil nique (SBT) Direct Cool Bath, capable of running either the
is cooled slowly. The second parameter is the temperature at calibration or the testing program with temperature control of
which the Gelation Index occurs. 60.1°C over the temperature range desired at 1°C⁄h.
6.5.1 Temperature Controller, is set up to operate according
6. Apparatus
totwoprograms,theCalibrationprogramandthetestprogram.
At any temperature the controller modulates temperature
6.1 TestCell,showninFig.1,consistingofamatchedrotor
and a stator of the following critical dimensions: within 0.1°C of the desired value.
6.1.1 Rotor dimensions for: critical length is 65.5mm
6.6 Computer, Analog-to-Digital Converter, and Analysis
(60.1mm) and critical diameter is 18.40mm (60.02mm).
Program, means of receiving data from the viscometer drive
6.1.2 Stator dimensions for: critical diameter is 22.05mm
module and converting this data into the desired information.
(60.02mm) at whatever length will satisfy the immersion
6.7 Sample Preheater—A programmable water bath, air
depth when the upper oil level is a minimum of 15mm below
bath or oven, or dry bath (integrated or separate) for precise
the cooling liquid level over the entire temperature range.
control of the test oils at 90°C 6 2°C during immersion time
6.2 Viscometer Drive Modules, rotational viscometer drive
afterthesamplereachespre-treatmenttemperature.SBTDirect
modules capable of producing an analog signal to an analog-
Cool bath can also perform the preheating portion of the test.
to-digital converter or other analog signal data processor such
6.8 Thermometer—Calibrated liquid-in-glass or digital con-
as a strip-chart recorder.
tact thermometer meeting the following requirements:
6.2.1 With the rotor and stator described in 6.1.1 and 6.1.2,
6.8.1 Calibrated Liquid-in-Glass Thermometer—One cali-
the viscometer drive module shall be capable of measuring to
brated at 90°C and reading to 60.2°C and another calibrated
at least 45000mPa·s (cP).
at –20°C reading to 60.1°C.
6.3 Test Cell Alignment Device, simultaneously maintains a
6.8.2 Digital Contact Thermometer—A DCT meeting the
vertical axial alignment and reasonably consistent positioning
criteria of Table 1.
of the rotor in the stator to give repeatable torque readout from
7. Materials
test to test when setting up the apparatus for analysis.
6.3.1 Viscometer Support, supports the viscometer drive 7.1 Calibration Oil,aNewtoniancalibrationoilofspecified
module and aligns it vertically.
dynamicviscosityandviscosityindexoveratemperaturerange
6.3.2 Stator Collar—clamps the stator and supports it when of −5°C to −35°C.
the stator collar is attached to the viscometer support.
7.2 Gelation Index Reference Oils, GIR-Series, Non-
6.4 Ameansofprovidingadrygasatmosphereoverthetop Newtonian Reference Oils, having Gelation Indices of estab-
of the test sample is necessary to prevent condensation and lished values as well as related values for the Gelation Index
freezing of water on the oil surface. temperatures.
TABLE 1 Digital Contact Thermometer Criteria for the Independent Temperature Indicator
Parameter Liquid Baths Dry Baths
A
Nominal temperature range –40 °C to 0 °C
Display resolution, minimum 0.1 °C
B
Accuracy, minimum –40 °C to 0 °C: ±100 mK (±0.1 °C)
Sensor type PRT
C
Immersion depth 114 mm (4.50 in.) minimum by Practice D7962 89 mm (3.50 in.) minimum by Practice D7962
D
Measurement drift less than 100 mK (0.1 °C) per year
E
Response time 12 s
F
Sensor sheath, max diameter 4.77 mm (0.188 in.) 3.18 mm (0.125 in.)
G
Sensor length, max 25 mm (1.0 in.)
H
Temperature calibration data When the ‘range-of-use’ is 30° or greater and less than 90° then at least 3 data points are required.
When the ‘range-of-use’ is 90° or greater, then at least 4 data points are required.
In all cases the calibration data is to be included in calibration report.
Temperature calibration report The DCT shall have a report of temperature calibration traceable to a national calibration or metrology standards
body issued by a competent calibration laboratory with demonstrated competency in temperature calibration. An
ISO 17025 accredited laboratory with temperature calibration in its accreditation scope would meet this
requirement.
A
A device’s minimum and maximum temperature may be different than the values shown provided the calibration requirements are met.
B
Accuracy is the total combined accuracy of the DCT unit, which includes the display, electronics, and sensor probe with correction factors.
C
Minimum probe immersion depth as determined by Practice D7962, or an equivalent procedure, and is to be equal to or less than the value in the table. This is the
minimum immersion needed to obtain an accurate temperature measurement. Thus, the actual immersion will likely exceed this minimum.
D
Drift is the difference between the corrected DCT temperature and a reference.
E
Response Time—This applies to a Digital Contact Thermometer’s (DCT) combined display and sensor system. Conformance with this requirement is to be provided in
the manufacturer’s or supplier’s product documentation. Response time is defined as the time for a DCT to respond to a 63.2 % step change in temperature. The step
change begins with the DCT probe at an initial temperature of 20 °C ± 5 °C in air and the timing begins when it is transferred to water at 77 °C ± 5 °C which is flowing
at 0.9 m/s ± 0.09 m/s past the sensor, as described in Test Method E644 or an equivalent method. The DCT display refresh rate is to be at intervals of every 3 seconds
or less.
F
Sensor sheath is the tube that holds the sensing element. The value is the nominal outside diameter of the sheath segment containing the sensing element.
G
The physical length of the temperature sensing element. Contact the DCT supplier to determine whether this parameter is met, as it will not be accessible to the user.
H
Minimum number of calibration data points used to establish calibration.
D5133 − 20a
TABLE 2 Program for Programmable Cooling Bath to Obtain
7.3 Finger Cots, latex, used to close the top of the oil-filled
Calibration Information—Calibration Profile
stators when they are in the sample preheater and subject to
Step Action °C Time
water condensation inside the stator.
A
1 Cool to −5 °C and hold −5
A
2 Stabilize bath at –5 °C −5
8. Sampling A
3 Set up data acquisition and −5
initiate program
8.1 Approximately a 20mL sample of test oil is necessary
4 Cool to –40 °C or until 40 000 cP −5 to –40 1 °C ⁄h or
B
for the test. is reached 2°C ⁄h
A
5 Return to –5 °C and hold −5
A
Indeterminate, non-critical period.
9. Preparation of the Apparatus
B
See Note 7 in 11.1.3.
9.1 Pretreat the samples using a preheater.
9.1.1 Water Baths—Using boiling distilled water and cor-
TABLE 3 Program for Programmable Cooling Bath to Obtain
recting for barometric pressure (if significant because of
Information on Test Oils
altitude of the laboratory), check the calibration of the liquid-
Step Action °C Time
in-glass or digital contact thermometer for 90°C used in the
A
1 Cool to −5 °C and hold −5
sample preheater by appropriate methods.
A
2 Stabilize bath at –5 °C −5
A
3 Set up data acquisition and initiate −5
9.1.1.1 Check that the water bath is filled with distilled
program
water to a level 20 mm above the oil level in the immersed
4 Cool to –40 °C or until 40 000 cP −5 to –40 1°C/h
stators and that the sample preheater temperature is 90°C 6
is reached
A
5 Return to –5 °C and hold −5
2°C. Complete this check upon initial set-up or if test results
A
indicate suspicious viscous behavior of the sample. Examples
Indeterminate, non-critical period.
of such behavior might include non-repeatable Gelation Indi-
ces or GI temperature for a given fluid, unexpectedly high or
9.3 Check to see that the upper hook threaded (left hand
lowGelationIndices,gelationatanunexpectedtemperature,or
non-repeatable viscosity-temperature curves. thread) to the viscometer drive module’s driveshaft is firmly
finger-tightened. In the tightening process gently and slightly
9.1.2 Air Baths or Ovens and Separate Dry-block Heaters—
lift the driveshaft.
Check the calibration of the temperature sensing device by
appropriate methods. The temperature should be constant at
NOTE4—Do notpulldownorpushorpulllaterallyonthedriveshaftas
90°C 62°C.Completethischeckuponinitialset-uporiftest
this may harm the internal jeweled bearing and perhaps bend the
driveshaft as well.
results indicate suspicious viscous behavior of the sample.
Examples of such behavior might include non-repeatable
10. Calibration of the Programmable Cooling Bath and
Gelation Indices or GI temperature for a given fluid, unexpect-
Preparation for Calibration of the Test Cell
edly high or low Gelation Indices, gelation at an unexpected
10.1 Using the programmable cooling bath temperature
temperature, or non-repeatable viscosity-temperature curves.
controllerandmanufacturer’sinstructions,temporarilysetbath
9.1.2.1 Determine the length of time required to bring the
temperature at –20°C and allow to come to equilibrium for
sample up to 90°C. Use this time interval to establish the
1h. For the dry block bath, fill the test cells with 40mL of
length of time the sample is held in the preheater.
methanol and place a rubber stopper on the cells. Check liquid
NOTE 2—Preheaters integral to the dry block bath and calibrated at
bath temperature, or cell temperature for the dry block bath,
–20°C can reasonably be assumed to hold 90°C 6 2°C without
using an independent, accurate and sensitive temperature
additional checks.
indicatorsuchasashort-range,partial-immersionthermometer
9.2 Preparing Programmable Cooling Bath—If using a oradigitalcontactthermometer(DCT)thatmeetsthecriterain
liquid bath, fill to proper depth according to supplier’s instruc- Table 1. If using a DCTwith the liquid bath, insert the DCTso
tions at –5°C. the tip of the probe is between 115 mm and 120 mm below the
surface of the bath fluid. If using a DCT with the dry block
NOTE 3—To ensure adequate cooling fluid height above the sample, it
bath, insert the DCT so the tip of the probe is between 90 mm
is advisable to fill the liquid bath at –5°C to the appropriate level
and 95 mm from the surface of the methanol in the test cell. If
indicated by the manufacturer in the owner’s manual to avoid over-filling
theindependenttemperatureindicatorshowsthatthemeasured
the bath and to always bring the bath back to this temperature when on
stand-by. This slows the evaporation rate. In addition, for many liquid
temperature is more than 60.2°C from set point on the
baths, operation at some temperature moderately below room temperature
programmable cooling bath or the temperature indicator inte-
maintains best operational response. Finally, it prevents overflow of the
gral to the temperature controller, or both, either the controller
bathmediumduetoexpansionofthecoolingfluid.Coolingfluidmustnot
requiresadjustment,orthetemperatureindicatorintegraltothe
be added to the bath during a sample test or calibration to avoid
temperature deviations. controller is out of calibration, or both. Follow the manufac-
turer’s instructions for the programmable cooling bath to
9.2.1 Installorcheckthecoolingprogramsfortheprogram-
mitigate the situation.
mable cooling bath. The programs to be implemented are
10.1.1 Perform the steps described in 10.1 at least every
shown in Tables 2 and 3. Table 2 is for the calibration of a
6months.
coolingrateof2°Cperhour.Table3isthesampleprofilewith
a cooling rate of 1°C per hour. NOTE5—Anytimefollowingtheprocedureof10.1revealsadifference
D5133 − 20a
in temperature between the independent temperature indicator and the
resultsandifnoimprovementisshown,theprogramdeveloper
programmable cooling bath set point, after the situation has been
or equipment manufacturer should be contacted for advice.
mitigated it is recommended to calibrate the test cell by following the
11.2 Verifytheapparatusperformanceatleastonceperyear
steps of Section 11.
by running a check standard meeting the requirements in
10.2 Turn the programmable cooling bath on to control at
PracticeD6299.Anysingleresultshouldagreewiththeknown
–5°C.
GelationIndexandGelationIndexTemperatureofthestandard
10.3 At room temperature, pour the cali
...

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: D5133 − 20 D5133 − 20a
Standard Test Method for
Low Temperature, Low Shear Rate, Viscosity/Temperature
Dependence of Lubricating Oils Using a Temperature-
Scanning Technique
This standard is issued under the fixed designation D5133; 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*
1.1 This test method covers the measurement of the apparent viscosity of engine oil at low temperatures.
-1
1.2 A shear rate of approximately 0.2 s is produced at shear stresses below 100 Pa. Apparent viscosity is measured
continuously as the sample is cooled at a rate of 1 °C ⁄h over the range −5 °C to −40 °C, or to the temperature at which the viscosity
exceeds 40 000 mPa·s (cP).
1.3 The measurements resulting from this test method are viscosity, the maximum rate of viscosity increase (Gelation Index),
and the temperature at which the Gelation Index occurs.
1.4 Applicability to petroleum products other than engine oils has not been determined in preparing 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.
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 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.
2. Referenced Documents
2.1 ASTM Standards:
D341 Practice for Viscosity-Temperature Equations and Charts for Liquid Petroleum or Hydrocarbon Products
D3829 Test Method for Predicting the Borderline Pumping Temperature of Engine Oil
D4684 Test Method for Determination of Yield Stress and Apparent Viscosity of Engine Oils at Low Temperature
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D7962 Practice for Determination of Minimum Immersion Depth and Assessment of Temperature Sensor Measurement Drift
E644 Test Methods for Testing Industrial Resistance Thermometers
3. Terminology
3.1 Definitions:
3.1.1 apparent viscosity, n—the viscosity obtained by use of this test method.
3.1.1.1 Discussion—
See 3.1.7 for definition of viscosity and units.
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 May 1, 2020June 1, 2020. Published June 2020. Originally approved in 1990. Last previous edition approved in 20192020 as
D5133 – 19.D5133 – 20. DOI: 10.1520/D5133-20.10.1520/D5133-20A.
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.
*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
D5133 − 20a
3.1.2 digital contact thermometer (DCT), n—an electronic device consisting of a digital display and associated temperature
sensing probe.
3.1.2.1 Discussion—
This device consists 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 digital
output goes to a digital display or recording device, or both, that may be internal or external to the device.
3.1.2.2 Discussion—
The devices are often referred to as “digital thermometers,” however the term includes devices that sense temperature by means
other than being in physical contact with the media.
3.1.2.3 Discussion—
PET is an acronym for portable electronic thermometers, a subset of digital contact thermometers (DCT).
3.1.3 Newtonian oil, n—an oil that, or fluid that at a given temperature,temperature exhibits a constant viscosity at all shear rates
or shear stresses.
3.1.4 non-Newtonian oil, n—an oil that, or fluid that at a given temperature,temperature exhibits a viscosity that varies with
changing shear stress or shear rate.
3.1.5 shear rate, n—velocity gradient perpendicular to the direction of flow.
3.1.5.1 Discussion—
-1
The SI unit for shear rate is the reciprocal second (1/s; also s ).
3.1.6 shear stress, n—force per unit area in the direction of flow.
3.1.6.1 Discussion—
The SI unit for shear stress is the Pascal (Pa).
3.1.7 viscosity, n—that property of a fluid which resists flow.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.
3.1.7.1 Discussion—
Viscosity is defined as the ratio of the applied shear stress (force causing flow) and the shear rate (resultant velocity of flow per
unit distance from a stationary surface wet by the fluid). Mathematically expressed:
viscosity 5 shear stress/shear rate or, symbolically, η5 τ/γ˙ (1)
in which the symbols in the second portion of Eq 1 are defined by the terms in the first portion of the equation. The SI
unit for viscosity used herein is milliPascal seconds (mPa·s).
3.2 Definitions of Terms Specific to This Standard:
3.2.1 air-binding oils—those engine oils whose borderline pumping temperatures are determined by a combination of gelation
and viscous flow.
3.2.2 borderline pumping temperature, n—that temperature at which an engine oil may have such poor flow characteristics that
the engine oil pump may not be capable of supplying sufficient lubricant to the engine.
3.2.3 calibration oil, n—Newtonian oils developed and used to calibrate the viscometer drive module over the viscosity range
required for this test method.
The sole source of supply of the equipment and materials known to the committee at this time is Tannas Co., 4800 James Savage Rd., Midland, MI 48642. If you are
aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the
responsible technical committee, which you may attend.
D5133 − 20a
3.2.3.1 Discussion—
these calibration oils are specially blended to give sufficient sensitivity and range for the special viscometer head used.
3.2.4 computer-programmed automated analysis, n—use of modern techniques for acquiring analog data, converting these to
digital values and using this information to automatically record and analyze torque output from the viscometer drive module and
to render this information into tabular data and plotted relationships.
3.2.4.1 analog-to-digital (A-D) converter, n—a device for converting continuously produced electrical signals into discrete
numerical values capable of being analyzed by computer technology.
3.2.5 critical pumpability temperature, n—the temperature in the programmable cooling bath at which an oil reaches a chosen
critical pumpability viscosity (see 3.2.6).
3.2.6 critical pumpability viscosity, n—that apparent viscosity believed to cause pumpability problems in an engine. This
apparent viscosity is chosen to test an oil for its critical pumpability temperature.
3.2.7 flow-limited oils, n—those oils whose borderline pumping temperatures are determined by viscous flow.
3.2.8 gelation, n—a rheological condition of an oil characterized by a marked increase in the flow resistance over and above
the normal exponential increase of viscosity with decreasing temperature, particularly at lower shear stresses and temperatures.
3.2.8.1 Discussion—
Gelation has been attributed to a process of nucleation and crystallization of components of the engine oil and the formation of
a structure.
3.2.9 Gelation Index, n—the maximum value of the incremental ratio
2 log logη 2 log logη #/ log T 2 log T (2)
@~ ! ~ ! ~ !
1 2 1 2
(in which η is dynamic viscosity and T is in degrees Kelvin) over the temperature range scanned when the incremental de-
crease in temperature is 1 K.
3.2.9.1 Discussion—
The technique of deriving Gelation Index was first developed and practiced collecting information from a strip-chart recording
and applying the empirical MacCoull-Walther-Wright equation (Test Method D341). For further information, see Appendix X1.
3.2.10 Gelation Index reference oils, n—non-Newtonian oils chosen to give certain levels of Gelation Index as a check on
instrument performance.
3.2.11 Gelation Index temperature, n—the temperature (t in Eq 2) in degrees Celsius at which the Gelation Index occurs.
3.2.12 programmable cooling bath, n—a liquid or dry block (referred to as direct cool) bath having a temperature controller
capable of being programmed to run the calibration and the analysis portions of the test method within the temperature tolerances
listed.
3.2.13 temperature controller, n—a programmable device which, when properly programmed, ramps the temperature upward
or downward at a chosen rate or series of steps while simultaneously controlling temperature excursions.
3.2.13.1 calibration program, n—a program to run the required series of temperatures at which the torque values necessary to
calibrate the viscometer drive module are collected and analyzed.
3.2.13.2 hold program, n—a program to reach and hold the programmable cooling bath at −5 °C.
3.2.13.3 test program, n—a program to run the test oil analysis at 1 °C ⁄h temperature decrease.
3.2.14 test cell, n—the combination of the rotor and stator. Critical elements of the test cell are sketched in Fig. 1.
3.2.14.1 rotor, n—a titanium rotor sized to give a compromise of sensitivity and range to the determination of viscosity and
gelation using this test method.
(1) stator, n—a precision-bore borosilicate glass or stainless steel tube, to which a measured amount of oil is added for the test
and within which the specially-made rotor turns.
(2) stator collar, n—a clamp for the stator which also positions it on the test cell alignment device.
3.2.15 sample preheater, n—a water bath, air bath or oven, or dry bath (integrated or separate) to heat the samples for 1.5 h to
2.0 h at 90 °C 6 2 °C before testing.
Symposium on Low Temperature Lubricant Rheology Measurement and Relevance to Engine Operation, ASTM STP 1143, Rhodes, R. B., ed., ASTM, 1992.
Selby, T.W., “The Use of the Scanning Brookfield Technique to Study the Critical Degree of Gelation of Lubricants at Low Temperatures”, SAE Paper 910746, Society
of Automotive Engineers, 1991.
D5133 − 20a
FIG. 1 Test Cell
3.2.16 test cell alignment device , n—a special device used to support the viscometer drive module while maintaining the stator
and the rotor coaxial and vertical in regard to the viscometer driveshaft. Later designs permit dry gas into the cell to prevent
moisture and frost buildup.
3.2.17 test oil, n—any oil for which apparent viscosity is to be determined using the procedure described by this test method.
3.2.18 viscometer drive module, n—the rotor drive and torque-sensing component of a rotational viscometer.
3.2.19 viscometer module support, n—a part of the test cell alignment device supporting the viscometer drive module.
4. Summary of Test Method
4.1 After preheating approximately 20 mL of the test oil in a glass stator at 90 °C for 1.5 h to 2.0 h, the test cell containing the
test oil is attached to a suitable viscometer drive module and the test cell immersed in a programmable cooling bath and cooled
at 1 °C ⁄h over the temperature range of −5 °C to −40 °C. Data from the viscometer drive module is collected and fed to a
computerized data assimilation program to determine the Gelation Index, Gelation Index temperature, and Critical Pumpability
temperature for a selected viscosity such as 30 000 mPa·s or 40 000 mPa·s (cP).
5. Significance and Use
5.1 Significance of Low-Temperature, Low Shear Rate, Engine Oil Rheology—The low-temperature, low-shear viscometric
behavior of an engine oil determines whether the oil will flow to the sump inlet screen, then to the oil pump, then to the sites in
the engine requiring lubrication in sufficient quantity to prevent engine damage immediately or ultimately after cold temperature
starting.
5.1.1 Two forms of flow problems have been identified, flow-limited and air-binding behavior. The first form of flow
restriction, flow-limited behavior, is associated with the oil’s viscosity; the second, air-binding behavior, is associated with
gelation.
5.2 Significance of the Test Method—The temperature-scanning technique employed by this test method was designed to
determine the susceptibility of the engine oil to flow-limited and air-binding response to slow cooling conditions by providing
4,5,7
continuous information on the rheological condition of the oil over the temperature range of use. In this way, both viscometric
and gelation response are obtained in one test.
NOTE 1—This test method is one of three related to pumpability related problems. Measurement of low-temperature viscosity by the two other
pumpability Test Methods D3829 and D4684, hold the sample in a quiescent state and generate the apparent viscosity of the sample at shear rates ranging
-1
up to 15 sec and shear stresses up to 525 Pa at a previously selected temperature. Such difference in test parameters (shear rate, shear stress, sample
The test cell alignment device is covered by patents. Interested parties are invited to submit information regarding the identification of alternatives to this patented item
to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
Shaub, H., “A History of ASTM Accomplishments in Low Temperature Engine Oil Rheology,” Symposium on Low Temperature Lubricant Rheology Measurement and
Relevance to Engine Operation, ASTM STP 1143, Rhodes, R. B., ed., ASTM, 1992, pp. 1–19.
D5133 − 20a
motion, temperature scanning, and so forth) can lead to differences in the measured apparent viscosity among these test methods with some test oils,
particularly when other rheological factors associated with gelation are present. In addition, the three methods differ considerably in cooling rates.
5.3 Gelation Index and Gelation Index Temperature—This test method has been further developed to yield parameters called
the Gelation Index and Gelation Index temperature. The first parameter is a measure of the maximum rate of torque increase caused
by the rheological response of the oil as the oil is cooled slowly. The second parameter is the temperature at which the Gelation
Index occurs.
6. Apparatus
6.1 Test Cell, shown in Fig. 1, consisting of a matched rotor and a stator of the following critical dimensions:
6.1.1 Rotor dimensions for: critical length is 65.5 mm (60.1 mm) and critical diameter is 18.40 mm (60.02 mm).
6.1.2 Stator dimensions for: critical diameter is 22.05 mm (60.02 mm) at whatever length will satisfy the immersion depth
when the upper oil level is a minimum of 15 mm below the cooling liquid level over the entire temperature range.
6.2 Viscometer Drive Modules, rotational viscometer drive modules capable of producing an analog signal to an analog-to-
digital converter or other analog signal data processor such as a strip-chart recorder.
6.2.1 With the rotor and stator described in 6.1.1 and 6.1.2, the viscometer drive module shall be capable of measuring to at
least 45 000 mPa·s (cP).
6.3 Test Cell Alignment Device, simultaneously maintains a vertical axial alignment and reasonably consistent positioning of the
rotor in the stator to give repeatable torque readout from test to test when setting up the apparatus for analysis.
6.3.1 Viscometer Support, supports the viscometer drive module and aligns it vertically.
6.3.2 Stator Collar—clamps the stator and supports it when the stator collar is attached to the viscometer support.
6.4 A means of providing a dry gas atmosphere over the top of the test sample is necessary to prevent condensation and freezing
of water on the oil surface.
6.5 Programmable Liquid or Scanning Brookfield Technique (SBT) Direct Cool Bath, capable of running either the calibration
or the testing program with temperature control of 60.1 °C over the temperature range desired at 1 °C ⁄h.
6.5.1 Temperature Controller, is set up to operate according to two programs, the Calibration program and the test program. At
any temperature the controller modulates temperature within 0.1 °C of the desired value.
6.6 Computer, Analog-to-Digital Converter, and Analysis Program, means of receiving data from the viscometer drive module
and converting this data into the desired information.
6.7 Sample Preheater—A programmable water bath, air bath or oven, or dry bath (integrated or separate) for precise control of
the test oils at 90 °C 6 2 °C during immersion time after the sample reaches pre-treatment temperature. SBT Direct Cool bath
can also perform the preheating portion of the test.
6.8 Thermometer—Calibrated liquid-in-glass or digital contact thermometer meeting the following requirements:
6.8.1 Calibrated Liquid-in-Glass Thermometer—One calibrated at 90 °C and reading to 60.2 °C and another calibrated at
–20 °C reading to 60.1 °C.
6.8.2 Digital Contact Thermometer—A DCT meeting the criteria of Table 1.
7. Materials
7.1 Calibration Oil, a Newtonian calibration oil of specified dynamic viscosity and viscosity index over a temperature range
of −5 °C to −35 °C.
7.2 Gelation Index Reference Oils, GIR-Series, Non-Newtonian Reference Oils, having Gelation Indices of established values
as well as related values for the Gelation Index temperatures.
7.3 Finger Cots, latex, used to close the top of the oil-filled stators when they are in the sample preheater and subject to water
condensation inside the stator.
8. Sampling
8.1 Approximately a 20 mL sample of test oil is necessary for the test.
9. Preparation of the Apparatus
9.1 Pretreat the samples using a preheater.
9.1.1 Water Baths—Using boiling distilled water and correcting for barometric pressure (if significant because of altitude of the
laboratory), check the calibration of the liquid-in-glass or digital contact thermometer for 90 °C used in the sample preheater by
appropriate methods.
9.1.1.1 Check that the water bath is filled with distilled water to a level 20 mm above the oil level in the immersed stators and
that the sample preheater temperature is 90 °C 6 2 °C. Complete this check upon initial set-up or if test results indicate suspicious
D5133 − 20a
TABLE 1 Digital Contact Thermometer Criteria for the Independent Temperature Indicator
Parameter Liquid Baths Dry Baths
A
Nominal temperature range –40 °C to 0 °C
Display resolution, minimum 0.1 °C
B
Accuracy, minimum –40 °C to 0 °C: ±100 mK (±0.1 °C)
Sensor type PRT
C
Immersion depth 114 mm (4.50 in.) minimum by Practice D7962 89 mm (3.50 in.) minimum by Practice D7962
D
Measurement drift less than 100 mK (0.1 °C) per year
E
Response time 12 s
F
Sensor sheath, max diameter 4.77 mm (0.188 in.) 3.18 mm (0.125 in.)
G
Sensor length, max 25 mm (1.0 in.)
H
Temperature calibration data When the ‘range-of-use’ is 30° or greater and less than 90° then at least 3 data points are required.
When the ‘range-of-use’ is 90° or greater, then at least 4 data points are required.
In all cases the calibration data is to be included in calibration report.
Temperature calibration report The DCT shall have a report of temperature calibration traceable to a national calibration or metrology standards
body issued by a competent calibration laboratory with demonstrated competency in temperature calibration. An
ISO 17025 accredited laboratory with temperature calibration in its accreditation scope would meet this
requirement.
A
A device’s minimum and maximum temperature may be different than the values shown provided the calibration requirements are met.
B
Accuracy is the total combined accuracy of the DCT unit, which includes the display, electronics, and sensor probe with correction factors.
C
Minimum probe immersion depth as determined by Practice D7962, or an equivalent procedure, and is to be equal to or less than the value in the table. This is the
minimum immersion needed to obtain an accurate temperature measurement. Thus, the actual immersion will likely exceed this minimum.
D
Drift is the difference between the corrected DCT temperature and a reference.
E
Response Time—This applies to a Digital Contact Thermometer’s (DCT) combined display and sensor system. Conformance with this requirement is to be provided in
the manufacturer’s or supplier’s product documentation. Response time is defined as the time for a DCT to respond to a 63.2 % step change in temperature. The step
change begins with the DCT probe at an initial temperature of 20 °C ± 5 °C in air and the timing begins when it is transferred to water at 77 °C ± 5 °C which is flowing
at 0.9 m/s ± 0.09 m/s past the sensor, as described in Test Method E644 or an equivalent method. The DCT display refresh rate is to be at intervals of every 3 seconds
or less.
F
Sensor sheath is the tube that holds the sensing element. The value is the nominal outside diameter of the sheath segment containing the sensing element.
G
The physical length of the temperature sensing element. Contact the DCT supplier to determine whether this parameter is met, as it will not be accessible to the user.
H
Minimum number of calibration data points used to establish calibration.
viscous behavior of the sample. Examples of such behavior might include non-repeatable Gelation Indices or GI temperature for
a given fluid, unexpectedly high or low Gelation Indices, gelation at an unexpected temperature, or non-repeatable viscosity-
temperature curves.
9.1.2 Air Baths or Ovens and Separate Dry-block Heaters—Check the calibration of the temperature sensing device by
appropriate methods. The temperature should be constant at 90 °C 6 2 °C. Complete this check upon initial set-up or if test results
indicate suspicious viscous behavior of the sample. Examples of such behavior might include non-repeatable Gelation Indices or
GI temperature for a given fluid, unexpectedly high or low Gelation Indices, gelation at an unexpected temperature, or
non-repeatable viscosity-temperature curves.
9.1.2.1 Determine the length of time required to bring the sample up to 90 °C. Use this time interval to establish the length of
time the sample is held in the preheater.
NOTE 2—Preheaters integral to the dry block bath and calibrated at –20 °C can reasonably be assumed to hold 90 °C 6 2 °C without additional checks.
9.2 Preparing Programmable Cooling Bath—If using a liquid bath, fill to proper depth according to supplier’s instructions at
–5 °C.
NOTE 3—To ensure adequate cooling fluid height above the sample, it is advisable to fill the liquid bath at –5 °C to the appropriate level indicated by
the manufacturer in the owner’s manual to avoid over-filling the bath and to always bring the bath back to this temperature when on stand-by. This slows
the evaporation rate. In addition, for many liquid baths, operation at some temperature moderately below room temperature maintains best operational
response. Finally, it prevents overflow of the bath medium due to expansion of the cooling fluid. Cooling fluid must not be added to the bath during a
sample test or calibration to avoid temperature deviations.
9.2.1 Install or check the cooling programs for the programmable cooling bath. The programs to be implemented are shown in
Tables 2 and 3. Table 2 is for the calibration of a cooling rate of 2 °C per hour. Table 3 is the sample profile with a cooling rate
TABLE 2 Program for Programmable Cooling Bath to Obtain
Calibration Information—Calibration Profile
Step Action °C Time
A
1 Cool to −5 °C and hold −5
A
2 Stabilize bath at –5 °C −5
A
3 Set up data acquisition and −5
initiate program
4 Cool to –40 °C or until 40 000 cP −5 to –40 1 °C ⁄h or
B
is reached 2 °C ⁄h
A
5 Return to –5 °C and hold −5
A
Indeterminate, non-critical period.
B
See Note 7 in 11.1.3.
D5133 − 20a
TABLE 3 Program for Programmable Cooling Bath to Obtain
Information on Test Oils
Step Action °C Time
A
1 Cool to −5 °C and hold −5
A
2 Stabilize bath at –5 °C −5
A
3 Set up data acquisition and initiate −5
program
4 Cool to –40 °C or until 40 000 cP −5 to –40 1°C/h
is reached
A
5 Return to –5 °C and hold −5
A
Indeterminate, non-critical period.
of 1 °C per hour.
9.3 Check to see that the upper hook threaded (left hand thread) to the viscometer drive module’s driveshaft is firmly
finger-tightened. In the tightening process gently and slightly lift the driveshaft.
NOTE 4—Do not pull down or push or pull laterally on the driveshaft as this may harm the internal jeweled bearing and perhaps bend the driveshaft
as well.
10. Calibration of the Programmable Cooling Bath and Preparation for Calibration of the Test Cell
10.1 Using the programmable cooling bath temperature controller and manufacturer’s instructions, temporarily set bath
temperature at –20 °C and allow to come to equilibrium for 1 h. For the dry block bath, fill the test cells with 40 mL of methanol
and place a rubber stopper on the cells. Check liquid bath temperature, or cell temperature for the dry block bath, using an
independent, accurate and sensitive temperature indicator such as a short-range, partial-immersion thermometer or a digital contact
thermometer (DCT) that meets the critera in Table 1. If using a DCT with the liquid bath, insert the DCT so the tip of the probe
is between 115 mm and 120 mm below the surface of the bath fluid. If using a DCT with the dry block bath, insert the DCT so
the tip of the probe is between 90 mm and 95 mm from the surface of the methanol in the test cell. If the independent temperature
indicator shows that the measured temperature is more than 60.2 °C from set point on the programmable cooling bath or the
temperature indicator integral to the temperature controller, or both, either the controller requires adjustment, or the temperature
indicator integral to the controller is out of calibration, or both. Follow the manufacturer’s instructions for the programmable
cooling bath to mitigate the situation.
10.1.1 Perform the steps described in 10.1 at least every 6 months.
NOTE 5—Any time following the procedure of 10.1 reveals a difference in temperature between the independent temperature indicator and the
programmable cooling bath set point, after the situation has been mitigated it is recommended to calibrate the test cell by following the steps of Section
11.
10.2 Turn the programmable cooling bath on to control at –5 °C.
10.3 At room temperature, pour the calibration oil to the fill line (Fig. 1) of the stators to be calibrated and place in a suitable
rack until ready. For stainless steel stators, insert 16 mL of sample using a volume-measuring dev
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