In the kinematic measuring method, gravity is the only force that acts on the sample. The mass (or weight) of a fluid is determined by gravity. Therefore, we say that steel has a greater density than ice cube. Both units are large and, for practical purposes, it's more common to use the centipoise (cP) and centistoke (cSt), which are equal to one one-hundredth of the corresponding whole unit. They may be the same size, but the steel cube weighs more than the ice cube. A corresponding unit for kinematic viscosity is the stoke (St), which is equivalent to 1 centimeter 2 per second. Think about an ice cube and a cube of steel. Viscosity Conversion Chart including Centipoise (CPS) Millipascal (mPas) Poise (P) Centistokes (cSt) Stokes (S) Saybolt Seconds Universal (SSU). Other Common Viscosity Units Some non-standard units include the Reyn, which is a British unit of dynamic viscosity. Sometimes the unit centistokes (cSt) is also used. Dynamic (cP) / Density = Kinematic (cSt)įor a given sample, with a density greater than one, dynamic viscosity will always be the higher number.ĭensity is the ratio of the mass (or weight) of the sample divided by the volume of the sample. The cgs unit for kinematic viscosity is stoke (St) and has been named after Irish mathematician and physicist Sir George Gabriel Stokes.Kinematic (cSt) x Density = Dynamic (cP).Density actually provides a way to convert between a kinematic and a dynamic viscosity measurement. The unit of measure of kinematic viscosity is Centistokes (cSt).Ī basic difference between the dynamic and kinematic viscosity measurements is density. The time is converted directly to kinematic viscosity using a calibration constant provided for the specific tube. There are several ways to find the kinematic viscosity of a fluid, but the most common method is determining the time it takes a fluid to flow through a capillary tube. Put another way, kinematic viscosity is the measure of a fluid’s inherent resistance to flow when no external force, except gravity, is acting on it. The other way is to measure the resistive flow of a fluid under the weight of gravity. One way is to measure a fluid’s resistance to flow when an external force is applied. Water at 20 ☌ has a kinematic viscosity of about 1 cSt. Other units are: 1 St ( Stoke) = 1 cm 2/s = 10 −4 m 2/s. An oil that is 9.2 cSt will be nearly the same viscosity as an oil that is 9.3 cSt, yet one is an SAE 20 and the other is an SAE 30. You'll see the ranges for cSt compared to SAE numbers. The SI unit of the kinematic viscosity is m 2/s. The table at the right, SAE Viscosity Chart (High Temp), shows the equivalents for cSt and SAE viscosity numbers. An approximate equation is V (.22S-180/S) where V is in cSt and S is. SUS is the older 'English' Measurement and is measured at 100 F and 210 F. Essentially one is ISO (Internal standards Organization) cSt is measured at 40 C and 100 C. Youll see the ranges for cSt compared to SAE numbers. The kinematic viscosity is the ratio between the dynamic viscosity and the density of a fluid. They are both known as kinematic viscosities (a measure of restrictive flow). The table at the right, SAE Viscosity Chart (High Temp), shows the equivalents for cSt and SAE viscosity numbers.
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