ASTM_D_7945_-_15.pdf

Designation:D794515Standard Test Method forDetermination of Dynamic Viscosity and Derived KinematicViscosity of Liquids by Constant Pressure Viscometer1This standard is issued under the fixed designation D7945;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method covers the measurement of dynamicviscosity and density for the purpose of derivation of kinematicviscosity of petroleum liquids,both transparent and opaque.The kinematic viscosity,in this test method is derived bydividing the dynamic viscosity,by the density,obtained atthe same test temperature.1.2 The result obtained from this test method is dependentupon the behavior of the sample and is intended for applicationto liquids for which primarily the shear stress and shear rate areproportional(Newtonian flow behavior).1.3 The range of kinematic viscosity covered by this testmethod is from 0.5 mm2/s to 1000 mm2/s in the temperaturerange between 40 C to 120 C;however the precision hasbeen determined only for fuels and oils in the range of 2.06mm2/s to 476 mm2/s at 40 C and 1.09 to 107 mm2/s at 100 C(as stated in Section 12 on Precision and Bias).The precisionhas only been determined for those materials,viscosity ranges,and temperatures as indicated in Section 12 on Precision andBias.The test method can be applied to a wider range ofmaterials,viscosity,and temperature.For materials not listed inSection 12 on Precision and Bias,the precision and bias maynot be applicable.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D445 Test Method for Kinematic Viscosity of Transparentand Opaque Liquids(and Calculation of Dynamic Viscos-ity)D2162 Practice for Basic Calibration of Master Viscometersand Viscosity Oil StandardsD6300 Practice for Determination of Precision and BiasData for Use in Test Methods for Petroleum Products andLubricantsD6708 Practice for Statistical Assessment and Improvementof Expected Agreement Between Two Test Methods thatPurport to Measure the Same Property of a Material2.2 ISO Standards:3ISO 5725 Accuracy(Trueness and Precision)of Measure-ment Methods and ResultsISO/IEC 17025 General Requirements for the Competenceof Testing and Calibration Laboratories3.Terminology3.1 Definitions:3.1.1 density(),nmass per unit volume.3.1.2 dynamic viscosity(),nthe ratio between the appliedshear stress and rate of shear of a liquid.3.1.2.1 DiscussionIt is sometimes called the coefficient ofdynamic viscosity or,simply,viscosity.Thus,dynamic viscos-ity is a measure of the resistance to flow or to deformation ofa liquid under external shear forces.3.1.2.2 DiscussionThe term dynamic viscosity can also beused in a different context to denote a frequency-dependentquantity in which shear stress and shear rate have a sinusoidaltime dependence.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.07 on Flow Properties.Current edition approved July 1,2015.Published July 2015.Originally publishedin 2014.Last previous edition approved in 2014 as D7945 14.DOI:10.1520/D7945-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.3 kinematic viscosity(),nthe ratio of the dynamicviscosity()to the density()of a liquid.3.1.3.1 DiscussionFor gravity flow under a given hydro-static head,the pressure head of a liquid is proportional to itsdensity().Therefore the kinematic viscosity()is a measureof the resistance to flow of a liquid under gravity.4.Summary of Test Method4.1 A test specimen is introduced into the measuring cells,which are controlled at a specified and known temperature.Themeasuring cells consist of a horizontal capillary tube withoptical sensors and an oscillating U-tube densitometer.Thedynamic viscosity is determined from the flow time of the testspecimen along the capillary under a constant pressure ofcompressed air in conjun