ASTM D4741-96

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4741 – 96 An American National Standard
Standard Test Method for
Measuring Viscosity at High Temperature and High Shear
Rate by Tapered-Plug Viscometer
This standard is issued under the fixed designation D 4741; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope D 4683 Test Method for Measuring Viscosity at High Shear
Rate and High Temperature by Tapered Bearing Simula-
1.1 This test method covers the laboratory determination of
6 −1
tor
the viscosity of oils at 150°C and 1 3 10 s using Ravenfield
D 5481 Test Method for Measuring Apparent Viscosity at
high shear rate tapered-plug viscometer models BE or BS.
High-Temperature and High-Shear Rate by Multicell Cap-
This test method may readily be adapted to other conditions if
illary Viscometer
required.
2.2 Coordinating European Council (CEC) Standard:
1.2 Newtonian calibration oils are used to adjust the work-
L-36 Test Method for the Measurement of Lubricant Dy-
ing gap and for calibration of the apparatus. These calibration
namic Viscosity under Conditions of High Shear
oils cover a range from approximately 1.8 to 5.9 cP (mPa.s) at
2.3 Institute of Petroleum (IP) Standard:
150°C. This test method should not be used for extrapolation to
IP-370 Test Method for the Measurement of Lubricant
higher viscosities than those of the Newtonian calibration oils
Dynamic Viscosity under Conditions of High Shear using
used for calibration of the apparatus.
the Ravenfield Viscometer
1.3 A non-Newtonian reference oil is used to check that the
working conditions are correct. The exact viscosity appropriate
3. Terminology
to each batch of this oil is established by testing on a number
3.1 Definitions:
of instruments in different laboratories. The agreed value for
3.1.1 apparent viscosity—the determined viscosity obtained
this check oil may be obtained by reference to the chairman of
by this test method.
the CEC Surveillance Group for the Ravenfield tapered-plug
3.1.2 density—the mass per unit volume. In the SI, the unit
viscometer method L-36 or to the distributor.
of density is the kg/m , but for practical use a submultiple is
1.4 Applicability to products other than engine oils has not
3 3 3
more convenient. The g/cm is 10 kg/m and is customarily
been determined in preparing this method.
used.
1.5 This test method uses the centipoise (cP) as the unit of
3.1.3 kinematic viscosity—the ratio of the viscosity to the
viscosity. For information, the equivalent SI unit, the millipas-
density of a liquid. It is a measure of the resistance of flow of
cal second (mPa.s) is shown in parenthesis.
a liquid under gravity. In the SI, the unit of kinematic viscosity
1.6 This standard does not purport to address all of the
is the metre squared per second; for practical use, a submultiple
safety concerns, if any, associated with its use. It is the
(millimetre squared per second) is more convenient. The
responsibility of the user of this standard to establish appro-
centistokes (cSt) is 1 mm /s and is customarily used.
priate safety and health practices and determine the applica-
3.1.4 Newtonian oil or fluid—an oil or fluid which at a given
bility of regulatory limitations prior to use.
temperature exhibits a constant viscosity at all shear rates or
2. Referenced Documents shear stresses.
3.1.5 non-Newtonian oil or fluid—an oil or fluid which
2.1 ASTM Standards:
exhibits a viscosity that varies with changing shear stress or
D 91 Test Method for Precipitation Number of Lubricating
shear rate.
Oils
3.1.6 shear rate—the velocity gradient in fluid flow. The SI
−1
unit for shear rate is the reciprocal second (s ).
3.1.7 shear stress—the motivating force per area for fluid
This test method is under the jurisdiction of ASTM Committee D-02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
flow. The area is the area of shear. In the SI, the unit for shear
D02.07 on Flow Properties.
Current edition approved Apr. 10, 1996. Published June 1996. Originally
e1 4
published as D 4741 – 87. Last previous edition D 4741 – 87 (1996) . Annual Book of ASTM Standards, Vol 05.03.
2 5
This test method is technically identical to that described in CEC L-36 (under Available from the CEC, Madou Plaza, 25th Floor, Place Madou 1, B-1030
the jurisdiction of the CEC Engine Lubricants Technical Committee) and in Institute Brussels, Belgium.
of Petroleum method IP 370. Available from Institute of Petroleum, 61 New Cavendish St., London WIM
Annual Book of ASTM Standards, Vol 05.01. 8AR, U.K. 071636 1004.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 4741
NOTE 1—Warning: Extremely flammable. Vapors may cause flash fire.
stress is the Pascal (Pa).
See Annex A1.
3.1.8 viscosity—the ratio between the applied shear stress
and rate of shear. It is sometimes called the coefficient of
8. Sampling
dynamic viscosity. This coefficient is thus a measure of the
8.1 Test oils that are visually free from haze and particulates
resistance to flow of the liquid. In the SI, the unit of viscosity
need not be filtered before evaluation. A sample must be free of
is the pascal second (Pa.s); for practical use, a submultiple,
particles larger than 3 μm. If after filtration through a filter of
millipascal second (mPa.s), is more convenient. The centipoise
pore size 3 μm, a heavy concentration of smaller particles is
(cP) is 1 mPa.s and is customarily used.
still visible, it is wise at least to reduce their concentration by
3.2 Definitions of Terms Specific to This Standard:
further filtration. This will reduce the possibility of the par-
3.2.1 calibration oils—Newtonian oils used to establish the
ticles wedging in the measurement gap and so causing erosion
reference framework of viscosity versus torque from which is
of the rotor/stator or erroneous readings. Do not filter formu-
determined the test oil viscosity.
lated oils through pore sizes below 1 μm because certain
3.2.2 non-Newtonian check oil—non-Newtonian oil used to
lubricant additives could be removed.
check that the gap or distance between the rotor and stator will
produce the desired operating shear rate of 1 3 10 s−1.
9. Preparation of Apparatus
3.2.3 test oil—any oil for which apparent viscosity is to be
9.1 Insertion of Stator—For detailed instructions, see
determined.
Manufacturer’s Manual.
4. Summary of Test Method
9.1.1 Remove the top nylon cover from the stator housing.
9.1.2 Remove the screwed cover.
4.1 The lubricant under test fills the annulus between a
9.1.3 Place an “O” ring at the bottom of the heating-jacket
close-fitting rotor and stator. The rotor and stator have a slight,
chamber, making sure it is sitting correctly in the corner of the
matching taper to allow adjustment of the gap and hence the
housing.
shear rate. The rotor is spun at a known speed and the lubricant
9.1.4 Clean the stator thoroughly, preferably using an ultra-
viscosity is determined from measurements of the reaction
sonic bath.
torque by reference to a curve prepared using Newtonian
9.1.5 Insert the stator into its housing with the thermocouple
calibration oils.
pocket uppermost and at the left-hand side. Ensure that the
5. Significance and Use
stator is sitting squarely in the center of the housing.
9.1.6 Place a second “O” ring above the stator, positioning
5.1 Viscosity measured under the conditions of this test is
it in the corner formed between the stator and the housing.
thought to be representative of that at the temperatures and
9.1.7 Place the clamping ring (chamfered end down) on top
shear rates but not the pressures in the journal bearings of
of the “O” ring and replace the screwed cover as tightly as
internal combustion engines under operating conditions.
possible using the fingers only. Metal-to-metal contact should
5.2 The relevance of these conditions to the measurement of
be achieved both above and below the stator. Failure to do so
engine-oil viscosity has been discussed in many publications.
may result in movement of the stator.
6. Apparatus
9.1.8 Replace the top nylon cover.
9.1.9 Insert the thermocouple into its pocket. Secure the
6.1 Ravenfield Tapered Plug High Shear Viscometer —
Model BE (single speed) or BS (multispeed). The viscometer wire in the clamp provided on the top of the instrument base,
ensuring that the thermocouple reaches the bottom of the
uses a rotating tapered plug in a matched stator.
6.2 Calibration Weight, (supplied with instrument). pocket.
6.3 Wash Bottle, fitted with metal tip (supplied with instru- 9.1.10 Insert the spill-prevention ring.
ment). 9.2 Setting Zero:
6.4 Thermostatically Controlled Heating Bath, with fluid 9.2.1 Mechanical zero is determined by the balance of two
circulator. springs and is not adjustable.
6.5 Temperature Measuring Instrument, having a precision 9.2.2 Transducer zero is set by the manufacturer and only
not worse than 60.2°C at 150°C. requires readjustment if the internal mechanism is disas-
6.6 Vacuum Pump, with suitable liquid trap. sembled.
9.2.3 Electrical zero is set as follows:
7. Materials
9.2.3.1 Remove the rotor coupling from the motor shaft.
7.1 Newtonian Calibration Oils , CEC Reference Oils RL (Not necessary for Model BS.)
102-107. 9.2.3.2 Before setting electrical Zero and Span (see 9.3), the
7.2 Non-Newtonian Check Oil , CEC Reference Oil RL 90. apparatus must be switched on (with the motor switched off)
7.3 Washing Solvent, ASTM precipitation naphtha as speci- for a period of 30 min to achieve a stable condition. The
fied in Test Method D 91 or a solvent of similar volatility. heating bath must not be switched on at any time unless a
stator is correctly installed to avoid damage to the rotor/stator.
9.2.3.3 Switch the motor on and allow about 10 s for the
For a comprehensive review see “The Relationship Between High-Temperature
brake to release and the motor cage to stabilize. (Not necessary
Oil Rheology and Engine Operation,” ASTM Data Series Publication 62.
8 for Model BS.)
Under the jurisdiction of CEC Engine Lubricants Technical Committee.
Ravenfield Designs Ltd. are distributors. 9.2.3.4 The indicator shows a value varying only one or two
D 4741
digits up or down. The control labelled “Z” may now be used plete revolutions of the dial gage. Raise the ball stop until it is
to set the indicator, such that it swings symmetrically about supporting the upper system. Turn the handwheel so that the
000. lifting screw is well clear.
9.5.5 Using the washing solvent, flush out the stator several
NOTE 2—Even if the zero appears to have drifted, it must not be reset
times, turning the rotor gently with the fingers. Apply the
with the rotor inserted into the stator (Model BE only).
solvent to the top of the rotor and remove by suction at the side
9.3 Setting Full-Scale Deflection (Span):
arm.
9.3.1 Mechanical setting is not possible and is determined
NOTE 3—Solvent should be applied using a wash bottle fitted with a
by the characteristics of the low-temperature-coefficient
metal tip. (Warning—Extremely flammable. Vapors may cause flash fire.
springs only.
See Annex A1.)
9.3.2 Electrical full-scale deflection is set by applying a
9.5.6 Using the following oil flush procedures, introduce
known torque and adjusting the digital read-out to match this
calibration oil RL 106 into the measuring system until the rotor
value. This adjustment shall be carried out after setting
is just covered.
electrical zero (see 9.2.3).
9.3.2.1 Detach the top fiberglass cover from the instrument,
NOTE 4—The oil flush procedure, using the oil level pipe and running
after removing the securing screws.
the motor continuously, is the preferred method for introducing and
changing test oil. If quantities of test oil are limited, the solvent flush
9.3.2.2 Attach about 800 to 1000 mm of strong cotton
procedure may be used. The solvent flush procedure is described in
thread by a loop to the peg on the machined calibration drum
Appendix X2. The precision and bias statements in Section 13 do not
at the top of the swinging frame. About 300 mm from the loop,
apply to the solvent flush procedure.
tie another length of cotton thread about 300 mm long and
fasten this to an adjustable support (for example, a ring stand). 9.5.7 Mount the suction pipe on the top surface of the
instrument with its tip about 4 mm above the top of the stator
Attach the calibration weight (supplied) to the remaining free
end and adjust the assembly as shown in Annex A2. and about 2 mm away from the rotor drive coupling. The pipe
may be bent readily if the height is initially incorrect.
9.3.2.3 By means of the control labelled “S” on the panel,
set the indicator reading to the applied torque in gram 9.5.8 Switch on the suction pump.
9.5.9 Place about 5 to 10 mL of washing solvent into the
centimetres (calibration weight g 3 7 cm drum radius). This
adjustment must be carried out with the motor running on funnel. This is sufficent to ensure that some is drawn-off by the
suction pipe. The use of washing solvent at this stage is to
Model BE and stationary on Model BS.
9.3.3 After setting full-scale deflection, check the zero ensure that the rotor/stator is subjected to a periodic wash to
minimize buildup of deposits.
setting. It may be necessary to repeat both settings due to a
small amount of interaction. Both controls retain their setting 9.5.10 Fill the funnel with the first oil sample.
9.5.11 For XBE and BE models, switch on the motor using
and regular readjustment is not necessary.
9.4 Assembly and Installation of Rotor: the motor switch on the front panel. The start-up brake will be
heard to operate and release after a few seconds. For XBS and
9.4.1 Fit the rotor to the cleaned universal joint and secure
it using the set screw, noting that the numbered end of the rotor BS models, select 3000 r/min, 5 s (RAMP), 99 h (PAUSE), 1
(STEP), then switch the motor on.
is the top.
9.5.12 Wait until the oil has fallen to the neck of the funnel.
9.4.2 Fit the rotor coupling sleeve similarly.
Refill the funnel with a second portion of the oil sample.
9.4.3 Thoroughly clean this assembly, preferably using an
9.5.13 Wait until the oil has fallen to the neck of the funnel.
ultrasonic bath.
9.5.14 Switch off the suction pump.
9.4.4 Screw the rotor coupling sleeve on to the motor shaft
and lock it tightly in position.
NOTE 5—Since the motor is running all the time, the sample in the
9.4.5 Using any clean ca
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