ASTM D6080-97(2007)
(Practice)Standard Practice for Defining the Viscosity Characteristics of Hydraulic Fluids
Standard Practice for Defining the Viscosity Characteristics of Hydraulic Fluids
SIGNIFICANCE AND USE
The purpose of this practice is to establish viscosity designations derived from viscosities measured by test methods which have a meaningful relationship to hydraulic fluid performance. This permits lubricant suppliers, lubricant users, and equipment designers to have a uniform and common basis for designating, specifying, or selecting the viscosity characteristics of hydraulic fluids.
This practice is not intended to be a replacement for Classification D 2422. Rather, it is an enhancement intended to provide a better description of the viscosity characteristics of lubricants used as hydraulic fluids.
This practice implies no evaluation of hydraulic oil quality other than its viscosity and shear stability under the conditions specified.
While it is not intended for other functional fluids, this practice may be useful in high-shear-stress applications where viscosity index (VI) improvers are used to extend the useful operating temperature range of the fluid.
This practice does not apply to other lubricants for which viscosity classification systems already exist, for example, SAE J300 for automotive engine oils and SAE J306 for axle and manual transmission lubricants.
SCOPE
1.1 This practice covers all hydraulic fluids based either on petroleum, synthetic, or naturally-occurring base stocks. It is not intended for water-containing hydraulic fluids.
1.2 For determination of viscosities at low temperature, this practice uses millipascal·second (mPa·s) as the unit of viscosity. For reference, 1 mPa·s is equivalent to 1 centipoise (cP). For determination of viscosities at high temperature, this practice uses millimetre squared per second (mm2/s) as the unit of kinematic viscosity. For reference, 1 mm2/s is equivalent to 1 centistoke (cSt).
1.3 This practice is applicable to fluids ranging in kinematic viscosity from about 4 to 150 mm2/s as measured at a reference temperature of 40°C and to temperatures from −50 to +16°C for a fluid viscosity of 750 mPa·s.
Note 1—Fluids of lesser or greater viscosity than the range described in 1.3 are seldom used as hydraulic fluids. Any mathematical extrapolation of the system to either higher or lower viscosity grades may not be appropriate. Any need to expand the system should be evaluated on its own merit.
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Standards Content (Sample)
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Designation: D6080 – 97 (Reapproved 2007)
Standard Practice for
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Defining the Viscosity Characteristics of Hydraulic Fluids
This standard is issued under the fixed designation D6080; 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 D2983 Test Method for Low-Temperature Viscosity of
Lubricants Measured by Brookfield Viscometer
1.1 This practice covers all hydraulic fluids based either on
D5621 Test Method for Sonic Shear Stability of Hydraulic
petroleum, synthetic, or naturally-occurring base stocks. It is
Fluids
not intended for water-containing hydraulic fluids.
E29 Practice for Using Significant Digits in Test Data to
1.2 For determination of viscosities at low temperature, this
Determine Conformance with Specifications
practice uses millipascal·second (mPa·s) as the unit of viscos-
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2.2 Society of Automotive Engineers (SAE) Standards:
ity. For reference, 1 mPa·s is equivalent to 1 centipoise (cP).
J300 Engine Oil Viscosity Classification
For determination of viscosities at high temperature, this
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J306 Axle and Manual Transmission Lubricant Viscosity
practiceusesmillimetresquaredpersecond(mm /s)astheunit
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Classification
of kinematic viscosity. For reference, 1 mm /s is equivalent to
1 centistoke (cSt).
3. Terminology
1.3 Thispracticeisapplicabletofluidsranginginkinematic
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3.1 Definitions:
viscosityfromabout4to150mm /sasmeasuredatareference
3.1.1 density—the mass per unit volume.
temperature of 40°C and to temperatures from−50 to+16°C
3.1.2 hydraulic fluid—a fluid used in hydraulic systems for
for a fluid viscosity of 750 mPa·s.
transmitting power.
NOTE 1—Fluids of lesser or greater viscosity than the range described
3.1.3 in-service viscosity—the viscosity of fluid during
in1.3areseldomusedashydraulicfluids.Anymathematicalextrapolation
operation of a hydraulic pump or circuit components.
of the system to either higher or lower viscosity grades may not be
3.1.4 kinematic viscosity—the ratio of the viscosity to the
appropriate. Any need to expand the system should be evaluated on its
density of a liquid.
own merit.
3.1.4.1 Discussion—Kinematicviscosityisameasureofthe
2. Referenced Documents
resistance to flow of a liquid under gravity.
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3.1.5 Newtonian fluid—a fluid that at a given temperature
2.1 ASTM Standards:
exhibits a constant viscosity at all shear rates or shear stresses.
D445 Test Method for Kinematic Viscosity of Transparent
3.1.6 non-Newtonian fluid—a fluid that exhibits a viscosity
and Opaque Liquids (and Calculation of Dynamic Viscos-
that varies with changing shear stress or shear rate.
ity)
3.1.7 shear degradation—the decrease in molecular weight
D2270 Practice for Calculating Viscosity Index from Kine-
of a polymeric thickener (VI improver) as a result of exposure
matic Viscosity at 40 and 100°C
to high shear stress.
D2422 Classification of Industrial Fluid Lubricants by Vis-
3.1.8 shear rate—the velocity gradient in fluid flow.
cosity System
3.1.9 shear stability—the resistance of a polymer-thickened
fluid to shear degradation.
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This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
3.1.10 shear stress—the motivating force per unit area for
ProductsandLubricantsandisthedirectresponsibilityofSubcommitteeD02.N0.10
on Specifications. fluid flow.
Current edition approved Nov. 1, 2007. Published January 2008. Originally
3.1.11 viscosity—the ratio between the applied shear stress
approved in 1997. Last previous edition approved in 2002 as D6080–97(2002).
and shear rate.
DOI: 10.1520/D6080-97R07.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
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Standards volume information, refer to the standard’s Document Summary page on Available from Society of Automotive Engineers (SAE), 400 Commonwealth
the ASTM website. Dr., Warrendale, PA 15096-0001, http://www.sae.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D6080 – 97 (2007)
3.1.11.1 Discussion—Viscosity is sometimes called the co- 6. Procedure
efficient of dynamic viscosity. This coefficient is a measure of
6.1 The low temperature viscosity grade of a fluid is based
the resistance to flow of the liquid.
on the viscosity of new oil measured using a Brookfield
3.1.12 viscosity index (VI)—an arbitrary number used to viscometer, Test Method D2983.
characterize the variation of the kinematic viscosity of a fluid 6.1.1 Theviscosityshallbeinterpolatedfrommeasurements
with temperature. at three temperatures spanning th
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