Types of viscosity pdf

Physical and chemical properties of crude oil and oil products. This chart illustrates the effect of temperature on the viscosity of three typical waterbased coatings. Newton law of viscosity states that the shear stress on a fluid element layer is directly proportional to the rate of shear strain. Viscosity increases the difficulty of the basic equations. The fluid on the left has a lower viscosity than the fluid on the right. The effect of pressure and temperature on the viscosity of gases is illustrated in fig. Dynamic viscosity is the relationship between the shear stress and. Syrup and tar, on the other hand, have a high viscosity, as they are thick.

The density of water is gm 3 or we can say 1 gcm 3. A fluid which can not be compressed and have no viscosity falls in the category of ideal fluid. The stabinger viscometer uses a proprietary unit, the krebs unit ku. Review different pump types commonly used understand the difference between centrifugal pumps and positive displacement pumps. The bulk viscosity also called volume viscosity expresses a type of internal friction that resists the shearless compression or expansion of a fluid. Weight density or specific density of a fluid is defined as the ratio of the weight of fluid to its volume of the fluid. Viscosity, resistance of a fluid liquid or gas to a change in shape, or movement of neighbouring portions relative to one another. Viscosity is the force in dynes required to move a plane of 1 cm 2 area at a distance of 1 cm from another plane of 1 cm 2 area through a distance of 1 cm in 1 s. The hoeppler principle fritz hoppler, 1897 1955, german chemist, who designed this fallingball viscometer in 1933 7 conforms to din 53015 and iso 12058.

A basic introduction to rheology technology networks. Types of motor oil how to pick the right engine oil. The polymer melt viscosity is an important variable in the process and others because it effectively controls not just the way the process works but the strength of the final product. It is not a fundamental law of nature but an approximation that holds in some materials and fails in others.

As you can see from the table each grade is defined by multiple viscosity tests. These describe the flow of the fluid in different ways related to the way they are measured, however. A basic introduction to rheology rheology and viscosity introduction rheometry refers to the experimental technique used to determine the rheological properties of materials. Viscosity is determined by timing how long it takes the cup to empty, and is measured in cup seconds. All leading brands have one for service level sl, available in several viscosities. Not every viscometer is the same the type of viscosity it measures depends on its design. Orifice viscometers include the different varieties of cup viscometers. Throughout the range of shear rates common for calendering, extrusion, and injection molding 107000sec, the melt viscosity drops from pasec to 300 pasec, whereas a typical polyurethane of a similar hardness will drop from 7000 pasec to 300 pa. Viscosity is measured with various types of viscometers and rheometers. Weight density is called weight per unit volume of a fluid. When a fluid flows, the layers of fluid rub against one another, and in very viscous fluids, the friction is so great that the layers of flow pull against. Viscosity is a measure of the resistance of a fluid to deform under shear stress.

Viscosity is an internal property of a fluid that offers resistance to flow. The viscosity can be measured with help of machines like capillary tube viscometer. In cases where it is not possible to measure the oil at the standard temperatures, the kinematic viscosity can be measured at different temperatures. Kinematics kinematics is the branch of classical mechanics which describes the motion of point. Measuring the different types of viscosity with viscometers. In this book, we will see many examples of processes where the rates of heat transfer, mass transfer and chemical reaction between. Temperature control is realized via liquid bath thermostat, while an operator manually performs measurement and cleaning. Give your students an opportunity to truly understand why different volcanoes have different eruption styles. Two other terms in common use are kinematic viscosity and fluidity. These types of fluids are generally called structured fluids or complex fluids and their behavior can be better described using a rheometer which can measure a range of viscosities over a wider range of shear rates. Certain devices use other falling objects than balls, for. In the metric system, the unit of viscosity is the poise 1 p 1 g cm1 s1, which is subdivided to 100 centipoise cp.

A rheometer is used for those fluids that cannot be defined by a single value of viscosity and therefore require more parameters to be set and measured than is the case for a viscometer. An active solvent dissolves the binder and rapidly reduces viscosity the next two types work in combination with an active solvent, but have opposite effects on it. The physical principle of measurement is based on the rate at which a fluid flows under gravity through a capillary tube. Most processes are based on the use of fluids either as raw materials, reagents, or heat transfer media. The above mentioned types of fluids are discussed under in brief. A viscometer is an instrument used to measure the viscosity of a fluid. Viscosity and temperature lubricant viscosity decreases dramatically with increasing temperature loglog x relationship viscosity index v. It also has a destabilizing effect and gives rise to disorderly, random phenomena called turbulence. The apparent melt viscosity of cope elastomers decreases much less with the increase in shear rate than that of most other polymers 35. Viscosity is a measure of a fluids propensity to flow. These types of experiments were used to check early work. Viscosity classifications industrial lubricant cassifications iso international standards organisation viscosity classification the iso viscosity classification uses mm2s cst units and relates to viscosity at 40oc. The greater part of automated capillary viscometers features special capillaries working with less measuring volume than the original types, or covering an extended viscosity range. The more viscous a liquid, the greater is the quantity of energy required to produce a desired state.

Viscosity definition, meaning, types, formula, unit, example. Viscosity is a measure of the thickness of a fluid, and very gloppy fluids such as motor oil or shampoo are called viscous fluids. Molasses, for example, has a greater viscosity than water. The fluid which does not follow the newtons law of viscosity and relationship is depend upon all the three quantity i. Basically the fluids are classified into 5 types and these are. Orifice viscometers are easy to use manually, thanks to the fact that theyre simply dipped into the fluid being worked with making them popular. Environmental inorganic chemistry for engineers, 2017.

Dynamic viscosity absolute viscosity kinematic viscosity. Inspired by our 2015 back to basics webinar series and following the fundamentals of viscosity webinar, this webinar, we will be introducing the most common types of viscosity. Friction at the molecular level viscosity is, essentially, fluid friction. Viscosity is measured in terms of a ratio of shearing stress to the velocity gradient in a fluid. Viscosity measurement series constanttemperature baths for viscometers glass viscometers as per jis k 2283 3000 made in japan as per jis k 2283 3000 along with the growth of the petrochemistry, polymer chemistry, and other industries involving viscous materials, viscosity measurements are increasingly being performed for a variety of fluids. Viscosity simple english wikipedia, the free encyclopedia. The molecular viscosity is a property of the material that depends microscopically on bond strengths.

These describe the flow of the fluid in different ways related to the way they are measured, however they are interchangeable if the fluid density is known. A simple and effective guide to viscosity and its measurement. I think you are referring to kinematic viscosity and dynamic viscosity. Kinematic viscosity is the dynamic viscosity divided by the fluid density. Thus, a rheometer can be considered as a special type of viscometer. Types of fluid flowsteady, laminar, turbulent, compressible. Jul 08, 2016 the above mentioned types of fluids are discussed under in brief. In the centimetergramsecond cgs system the unit of viscosity is the poise p or centipoise 1 cp 0. Shear viscosity is a measure of resistance to isochoric. In our first viscometer series blog, we discussed the what and why of viscometers what they are and why theyre useful. The viscosity of oil is a measure of its resistance to internal flow and an indication of its oiliness in the lubrication of surfaces. Utilize cheap supplies to learn about viscosity, temperature, and volatiles in different types of magma. Dynamic viscosity is the relationship between the shear stress and the shear rate in a fluid. There are two ways to measure a fluids viscosity as follows.

The concept of viscosity fluid flow plays a very important part in the processing of materials. What was the need to define two types of viscosity. As they function using gravity, the viscosity measured is kinematic viscosity. Viscosity ranges from 32 1,000,000 ssu temperatures to. Viscosity is higher than 250 cps desire for constant flow, independent of pressure efficiency for low flow, higher pressure combinations. They work for fluids whose viscosity does not change under varying flow conditions. If a sphere is dropped into a fluid, the viscosity can be determined using the following formula. From the bottom half of the chart grade 40 it will also have a kinematic viscosity in the range 12. The root variable is molecular weight, which determines both properties. Properties of fluidmass density, specific weight, volume. Viscosity is measured with various types of viscometer, typically at 25c standard state. They work for fluids whose viscosity does not change under varying.

Temperature dependent kinematic viscosity of different types of engine oil article pdf available in acta universitatis agriculturae et silviculturae mendelianae brunensis 574 august 2009. In this blog, well be going over the how that is, how six different types of viscometers work. There are two different measurements of viscosity used to describe fluids, dynamic and kinematic viscosities. In a simple example, water has a low viscosity, as it is thin. For liquids with viscosities which vary with flow conditions, an instrument called a rheometer is used. Types of fluids in fluid mechanics mechanical booster. Viscosity is a property in which an induced stress such as a pressure difference between the two ends of a tube through which the fluid is flowing is needed to overcome the internal friction to keep the fluid moving. We can also define a kinematic turbulent viscosity. Close temperature control of the fluid is essential to acquire accurate measurements. Heat is energy of random motion at the molecular level, so to have any understanding of how this energy. The measurement should be performed according to astm d7042 8 or astm d445 9 respectively iso 3104 10 or ip 71 11. Viscosity of a polymer solution depends on concentration and size i.

Like friction between moving solids, viscosity transforms kinetic energy of macroscopic motion into heat energy. A way to test for viscosity is the speed at which the substance runs down a slope. A viscometer also called viscosimeter is an instrument used to measure the viscosity of a fluid. Viscosity is actually a measure of friction in the fluid. Dynamic viscosity is also known as absolute viscosity and most often relates to nonnewtonian fluids. These types of material exhibit different viscosities. A diluent, when added with an active solvent, extends a solution and also weakens the solvency power of the active solvent. It consists of a series of 18 2viscosity brackets between 1. Viscometers are used to measure viscosity in most circumstances.

Fluids that obey newton law of viscosity are known as newtonian fluids. Viscometers viscometers are used to measure viscosity in most circumstances. Different types of liquids display different characteristics when force is applied through mixing. Viscosity measurement and the principles of viscosity. Viscosity 4 types of viscosity viscosity, the slope of each line, varies among materials newtons law of viscosity, given above, is a constitutive equation like hookes law, ficks law, ohms law. Lecture 10 turbulence models applied computational fluid.

Numerical estimates for the bulk viscosity of ideal gases pdf. Pdf temperature dependent kinematic viscosity of different. Apr 27, 2015 topics introduction types of viscometer 4. These capillaries are not in accordance with the original standards, but offer comparable precision.

For some fluids, it is a constant over a wide range of shear rates. The kinematic viscosity is the relationship between viscous and inertial forces in a fluid. Its unit is the same as that of the molecular viscosity. Jul 12, 2015 i think you are referring to kinematic viscosity and dynamic viscosity. Syrup would reach the bottom very slowly, and water would be much quicker.

There are two kinds of viscosity commonly reported, kinematic and dynamic. Rotational viscometers measure the resistance of fluids to torque. The reciprocal of the viscosity is called the fluidity, a measure of the ease of flow. The viscosity of a fluid is a measure of its resistance to deformation at a given rate. As we know, the viscosity is the measure of the friction of fluids. Many are confused between the two viscosity measures and consider them to be one and the same. An orifice viscometer usually consists of a cup with a hole, through which the fluid flows.