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# The viscosity of the concept and conversion

Kinematic viscosity
Cst ( Centistokes, Li Stokes ): cst;
St ( Stokes, Stokes ): Sri Lanka
The international system of units: mm2/s: mm / sec
Conversion relationships: 1Cst = 10-2 St = 1 mm2/s

Dynamic viscosity:
CP ( Centipoise ): cp;
P ( Poise ): park;
The international system of units: Pa w s: W seconds.
Conversion relationships: 1cP = 10-2 P = 10-3 Pa s = 1 mPa w s w
Kinematic viscosity and viscosity relationship: 1 = ( P St 1 ) / ( 1 g/cm3 )

CST ( CST ) is the smallest unit of kinematic viscosity, CP ( cP ) is the smallest unit of dynamic viscosity, kinematic viscosity is the liquid in the gravity flow when the internal friction measurement, its value is the same temperature fluid dynamic viscosity and density ratio, in the international system of units in mm2/s. The dynamic viscosity of said liquid under certain shear stress under flow when the internal friction measurement, its value is imposed on the flowing liquid shear stress and shear rate ratio, in the international system of units to Pa ·s, use the cP representation. 1cP=10-3Pa s.
Viscosity unit is Stokes, namely Stokes, referred to as '. When the fluid dynamic viscosity of 1 berth, density is 1g/cm3 kinematic viscosity of 1 Stokes. CSt is the abbreviation for Centistokes, mean CST, 1 Stokes one percent.
CST ( CST ) is the smallest unit of kinematic viscosity, CP ( cP ) is the smallest unit of dynamic viscosity, kinematic viscosity is the liquid in the gravity flow when the internal friction measurement, its value is the same temperature fluid dynamic viscosity and density ratio, in the international system of units in mm2/s.
The dynamic viscosity of said liquid under certain shear stress under flow when the internal friction measurement, its value is imposed on the flowing liquid shear stress and shear rate ratio, in the international system of units to Pa ·s, use the cP representation. 1cP=10-3Pa s.
Viscosity is a liquid friction. Lubricating oil by external force and moves relatively to the oil molecules, the resistance to lubricating oil can flow smoothly, the resistance size called viscosity. It is a lubricating oil flow properties of the major technical indicators. The vast majority of the lubricating oil is based on its viscosity size to divide grades, therefore, all kinds of machinery and equipment selection of oil viscosity is the main basis. Viscosity measurement method is divided into absolute viscosity and relative viscosity of two kinds of. Absolute viscosity dynamic viscosity and kinematic viscosity is divided into two; relative viscosity with Engler viscosity, Saybolt Viscosity and viscosity Redwood several representation method.
1, dynamic viscosity in the fluid of two area of the 1m2, 1m apart, relative moving speed is 1m/s when the resistance is called dynamic viscosity. Unit Pa.s ( PA. Seconds ). Past use of dynamic viscosity unit parking or centipoise, Park ( Poise ) or centipoise is a legal unit of measurement. 1Pa.s=1N.s/m2=10P Park =10 3 CP = 1KcpsASTM D445 standards used to calculate the kinematic viscosity dynamic viscosity, i.e.η= P - V type ofη- dynamic viscosity, Pa.s targetingρ- density, kg/m3 V - kinematic viscosity, m2/s China national standard GB/T506-82 for lubricating oil low-temperature dynamic viscosity determination. The method used in the determination of lubricating oil and dark petroleum products at low temperature ( 0 ～-60 ℃) dynamic viscosity. In the strict control of temperature and under different pressures, determination of a certain volume of sample in the capillary viscometer calibration constant flows through the required time, seconds. By the sample in capillary flow of time and Capillary calibration constant and the average pressure of the product, calculation of dynamic viscosity, the unit is Pa.s. The method repeats the determination results of two difference should not exceed the arithmetic mean value of± 5%.
2, kinematic viscosityυfluid dynamic viscosity with temperature of the fluid densityρratio called the kinematic viscosity. It is this fluid under the action of gravity flow resistance measurement. In the international system of units ( SI ), kinematic viscosity unit is m2/s. The past usually use CST ( cSt ) as the kinematic viscosity of the unit, which is equal to 10-6m2/s ( i.e., 1cSt=1mm2/s. Kinematic viscosity is commonly used capillary viscometer astm. In strict temperature and can reproduce the driving head, determination of a volume of the liquid in the gravity flow calibrated capillary viscometer for measuring time, kinematic viscosity, we must control the measured fluid temperature, temperature measurement precision reaches 0.01 DEG C; the second must choose proper capillary size, ensure the efflux time not too long or not too short, namely the viscous liquid with slightly thicker capillary, thin liquid with slightly smaller capillary, the flow of time should not be less than 200 seconds; subject to periodic calibration constant viscosity tube; and installing viscosity tube must be vertical. Kinematic viscosity of national standards for the GB/T256-88, the equivalent of ASTM D445-96/IP71/75.
3, Engler viscosity 0E national standards for petroleum products Determination of Engler viscosity GB/T266-88. This is a commonly used relative viscosity, which is defined on the set temperature, the flow of fluid through the 200ml Engler viscometer time ( s ), with the same volume of distilled water at 20℃Engler viscometer. Through time ( s ) is called the Engler viscosity.
4, the viscosity viscosity Redwood (Redwood ) mainly in the UK and Japan used. Its definition is based on 50ml oil test in a specified temperature 60 ℃or 98.9 ℃dirty too Redwood viscosimeter required time, in seconds.
5, Saybolt universal viscosity ( Saybolt Universal Viscosity ) the United States used by this unit of viscosity, which is defined by a specified temperature Saybolt viscometer outflow of liquid from the 60ml time, in seconds. The United States of America standard method for ASTM D886, several viscosity conversion 1) Engler viscosity and kinematic viscosity kinematic viscosityυconversion ( mm2/s ) =7.310E-6.31/0E 2 ) Redwood viscosity and kinematic viscosity of the conversion motion viscosityυ=0.26R-172/R (mm2/s ) when R>225s, then V (mm2/s ) =0.26R 3 ) Saybolt Viscosity and kinematic viscosity conversion: V ( mm2/s ) =0.225S when S>285s with type.