Poise unit

This result is called the Poiseuille equation, after Poiseuille, who discovered this fourth-power dependence of flow rate on radius in 1844. The poise unit of viscosity is also named after this researcher. The following example illustrates the use of the Poiseuille equation in the area where it was first applied. 

The so-called zone theory of viscosity assumes that the energy of activation may not be localised in two degrees of freedom but (unless EJT is small) be spread over a zone of degrees of freedom, in the liquid, the size of the zone increasing with EJT. This loosens the liquid in the zone as a prerequisite for viscous flow or difiusion. Barrer considered that the equation rj in poise units) ... 

Table 3. Viscosity of silver paste with varies thinner weight percentage (in Poise unit)...

Incidentally, the viscosity of water at 20°C is conveniently approximately equal to 1 cP. However, the poise unit of viscosity itself was actually named after the French physician Poiseuille, who was studying blood flow and conducted extensive experiments on flow in tubes... 

Poise = cgs unit of absolute viscosity Centipoise = 0.01 poise Stoke = cgs unit of kinematic viscosity Centistoke = 0.01 stoke Centipoises = centistokes X density (at temperature under consideration)... 

The dynamic viscosity, or coefficient of viscosity, 77 of a Newtonian fluid is defined as the force per unit area necessary to maintain a unit velocity gradient at right angles to the direction of flow between two parallel planes a unit distance apart. The SI unit is pascal-second or newton-second per meter squared [N s m ]. The c.g.s. unit of viscosity is the poise [P] 1 cP = 1 mN s m . The dynamic viscosity decreases with the temperature approximately according to the equation log rj = A + BIT. Values of A and B for a large number of liquids are given by Barrer, Trans. Faraday Soc. 39 48 (1943). 

Kinematic viscosity v is the ratio of the dynamic viscosity to the density of a fluid. The SI unit is meter squared per second [m s ]. The c.g.s. units are called stokes [cm -s l] poises = stokes X density. 

Viscosity is equal to the slope of the flow curve, Tf = dr/dj. The quantity r/y is the viscosity Tj for a Newtonian Hquid and the apparent viscosity Tj for a non-Newtonian Hquid. The kinematic viscosity is the viscosity coefficient divided by the density, ly = tj/p. The fluidity is the reciprocal of the viscosity, (j) = 1/rj. The common units for viscosity, dyne seconds per square centimeter ((dyn-s)/cm ) or grams per centimeter second ((g/(cm-s)), called poise, which is usually expressed as centipoise (cP), have been replaced by the SI units of pascal seconds, ie, Pa-s and mPa-s, where 1 mPa-s = 1 cP. In the same manner the shear stress units of dynes per square centimeter, dyn/cmhave been replaced by Pascals, where 10 dyn/cm = 1 Pa, and newtons per square meter, where 1 N/m = 1 Pa. Shear rate is AH/AX, or length /time/length, so that values are given as per second (s ) in both systems. The SI units for kinematic viscosity are square centimeters per second, cm /s, ie, Stokes (St), and square millimeters per second, mm /s, ie, centistokes (cSt). Information is available for the official Society of Rheology nomenclature and units for a wide range of rheological parameters (11). 

The Iduematic viscosity (v) is defined as the ratio of the absolute viscosity to density at the same temperature and pressure. The most common unit corresponding to the poise is the stoke (1 cmVsec). The SI unit would be mVsec. 

NOTE AU groups are dimensionless. To convert dynes per square centimeter to joules per square meter, miJtiply by 10" to convert poises to newton-seconds per square meter, multiply by 10" to convert feet per second to meters per second, multiply by 0.3048 to convert feet to meters, multiply by 0.3048 to convert pounds per minute-foot to kilograms per second-meter, multiply by 0.025 to convert pounds per cubic foot to kilograms per cubic meter, multiply by 16.019 to convert pounds per minute squared to kilograms per second squared, multiply by 1.26 X lO"" to convert British thermal units per hour to kilojoules per second, multiply by 2.63 X lO"" and to convert British thermal units per hour-square foot-degree Fahrenheit per foot to joules per square meter-second-kelvin per meter, multiply by 1.7307. 

The unit of absolute viscosity is the Poise (P, g cm s or mPa s), while the unit for Idnematic viscosity is the Stoke (St, cm s Because of the large size of these viscosity units, absolute viscosities for ionic liquids are usually reported in centipoises (cP) and Idnematic viscosities reported in centistokes (cSt). 

The plate heat exchanger can also be used for evaporation of highly viscous fluids when the evaporation occurs in plate or the liquid flashes after leaving the plate. Applications generally have been restricted to the soap and food industries. The advantage of these units is their ability to concentrate viscous fluids of up to 50 poise. 

The resistance when moving one layer of liquid over another is the basis for the laboratory method of measuring absolute viscosity. Poise viscosity is defined as the force (pounds) per unit of area, in square inches, required to move one parallel surface at a speed of one centimeter-per-second past another parallel surface when the two surfaces are separated by a fluid film one centimeter thick. Figure 40.16. In the metric system, force is expressed in dynes and area in square centimeters. Poise is also the ratio between the shearing stress and the rate of shear of the fluid. 

A smaller unit of absolute viscosity is the centipoise, which is one-hundredth of a poise or 1 centipoise = 0.01 poise. 

Viscosity is a measurement of resistance to flow. Although the unit of absolute viscosity is poise, its measurement is difficult. Instead, kinematic (flowing) viscosity is determined by measuring the time for a given flow through a capillary tube of specific diameter and length. The unit of kinematic viscosity is the stoke. However, in general practice, centistoke is used. Poise is related to stoke by the equation ... 

Convert I poise to British Engineering units and SI units. 

The first-stage CSTR is completely filled and utilizes a pair of opposing axial flow turbines on the agitator shaft. The maximum recommended viscosity for this reactor is 40 poise and the turbine agitation is set such that total flow volume generated per unit time by the turbines is 500 to 1000 times the feed rate to the reactor. 

Pharmacy educators are poised to adapt to the changes in practice that will result from the widespread adoption of drug therapies based on pharma-cogenomics. Pharmacy education has been in a constant state of evolution since the early twentieth century, when the education of pharmacists consisted almost entirely of basic chemistry applied to those compounds thought to be useful as medications. At that time, many academic pharmacy programs were housed in departments of chemistry. Schools and colleges of pharmacy now are independent academic units, many of which are fully integrated into major academic health science centers. 

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