# Cup And Bob Viscometer Pdf

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## Viscometer

Viscosity Determination. Free pharmacy material. Viscosity is defined as the resistance in the flow of liquid. It is also defined as the internal friction between two layers of liquid which resists the flow of liquid.

Then he defined the viscosity as the resistance in the flow of liquid at applied stress. Size of molecules: High particle size solutions show high viscosity. That is, the size of the molecules is directly proportional to the viscosity.

Shape of the molecules: Spherical molecules show low viscosity. Inter-molecular forces: Large inter-molecular forces have greater viscosity. Temperature: Temperature is directly proportional to the viscosity. There are mainly four types of viscometers mainly employed for the determination of viscosity:. This is mainly based on the principle of the measurement of the time taken for the liquid to flow between the marks. This is commonly known as Ostwald viscometers. The Ostwald viscometers consist of a U-tube with two bulbs one is for sample.

A capillary tube is fixed above the U-tube. The liquid sample is filled in the bulb X, and the time is noted for the flow of the sample from Mark A to Mark B. This is then repeated for a known liquid such as water.

Then the viscosity of the sample is expressed by the following formula:. This equation is mainly based on Poiseuille's law for a liquid flowing through a capillary tube. Capillary viscometer. In this method, the metal or glass ball rolls down in a vertical glass tube which is filled with the sample solution.

The sample tube is filled with the sample solution. The ball is then immersed in the sample solution. The temperature of the sample tube is maintained with the water jacket surrounding the sample tube. Then, after attaining the temperature equilibrium, the whole system is inverted, that is, the ball is placed at the top of the solution, and the time taken for the ball from Mark A to Mark B is noted. The procedure is repeated several times for accurate results. Then the viscosity of the sample liquid is calculated from the following equation:.

Falling sphere viscometer. This method is also known as the Couette viscometer which is based on shear rates. The sample is sheared in the space between the outer wall of the bob and the inner wall of the cup into which the bob is fitted.

Then the viscosity is determined by the following formula:. Cup-Bob viscometer. The angular velocity is given by the following formula:. The main disadvantage of the cup and bob viscometer is variable shear across the sample between the bob and the cup. The cone is driven by variable speed motor and the sample solution is sheared in the narrow gap between the stationary plate and the rotating cone.

The sample solution is placed at the centre of the plate. Cone and plate viscometer. The viscosity is given by the following formula:. The SI units of the viscosity are the Pascal second or in cgs units poise or centi poise. Used in the determination of intrinsic viscosity. Used in the determination of light fuels.

Used in the control of polymerization. Used in the determination or study of the physical properties of liquids. Define viscosity. What are the factors affecting viscosity? Explain the principle involved in the cup and bob viscometer. Explain the principle involved in the capillary viscometer.

Explain the principle involved in the falling sphere viscometer. Explain the principle involved in the cone and plate viscometer. What are the applications of viscometer determinations? Post a comment. The conductance is defined as the current flow through the conductor. In other words, it is defined as the reciprocal of the resistance. This method is mainly used for the determination of the physico-chemical properties of the compounds.

The movement of the ions is mainly depended on the concentration of the ions. This replacement of the ions w. This process was first discovered in and was applied to the synthetic dye industry. The reaction mechanism was first proposed by Peter Griessin. In this method, the primary aromatic amine is reacted with the sodium nitrite in acidic medium to form a diazonium salt. This method is first used in the determination of dyes.

PRINCIPLE The principle involved in this method is that the primary aromatic amine present in the sample reacts with the sodium nitrite in the presence of acid such as hydrochloric acid to obtain a diazonium salt. The amine reacts with the nitrous acid to form nitrosamine, which is followed by the tautomerisation and the water mol.

## GENG 303 FLUID MECHANICS LABORATORY

'Cup and bob' viscometers work by defining the exact volume of sample which is to be sheared within a test cell, the torque required to achieve a.

## Viscometer

Viscosity Determination. Free pharmacy material. Viscosity is defined as the resistance in the flow of liquid. It is also defined as the internal friction between two layers of liquid which resists the flow of liquid. Then he defined the viscosity as the resistance in the flow of liquid at applied stress.

Capillary viscometer Ostwald viscometer Falling sphere viscometer Application:- Newtonian fluids Multipoint viscometer:-Equipment work at a several rate. The time of flow of the liquid under test is compared with the time required for a liquid of known viscosity. The tube with the jacket is then inverted, which places the ball at. The following equation is used to calculate the apparent viscosity of.

### Viscometer

Capillary viscometer Ostwald viscometer Falling sphere viscometer Application:- Newtonian fluids Multipoint viscometer:-Equipment work at a several rate. The time of flow of the liquid under test is compared with the time required for a liquid of known viscosity. The tube with the jacket is then inverted, which places the ball at. The following equation is used to calculate the apparent viscosity of. The sample required is small 0. Cleaning and filling is easy.

Uzeology derived from Greek rheos meaning 'flow' and logos meaning 'science' is the study f the flow or deformation of matter under the influence of stress. Rheology can be applied solids completely resistant to deformation , liquids moderately resistant to deformation and gases completely nonresistant to deformation. Pharmaceutical processing operations such as mixing of materials, filling and packaging into containers 2. Removal of product from package such as pouring from a bottle, extrusion from a tube, spraying liquids from atomizers and passage from syringe needle 3. Topical application of product onto skin 4. Physical stability of suspensions, emulsions and semisolids 5.

and angular velocity (of the cup) to the requisite shear rate, are widely available Figure Partial section of a concentric-cylinder viscometer along with their The particular solution to equation () for a finite cylindrical bob rotating.

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A viscometer also called viscosimeter is an instrument used to measure the viscosity of a fluid. For liquids with viscosities which vary with flow conditions , an instrument called a rheometer is used. Thus, a rheometer can be considered as a special type of viscometer.

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## Cara C.

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