What is the principle of viscometer?
These viscometers use the principle of ‘rotational viscometry’, i.e. their measurement of product viscosity is based upon immersing a specifically selected spindle within a sample of the product followed by measurement of the torque required to rotate the spindle at a set speed whilst immersed within the product sample …
What is viscometer used for?
A viscometer is an instrument used to measure fluid viscosity and the flow properties of liquids. Let’s discuss the various styles of viscometers, their internal characteristics and factors that go into performing a precise and repeatable viscosity measurement.
What is meant by viscometer?
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. The drag caused by relative motion of the fluid and a surface is a measure of the viscosity.
What is the SI and CGS unit of viscosity coefficient?
SI unit: Ns. m. -2. CGS unit: poise.
How does Ostwald viscometer work?
Ostwald viscometer is a commonly used viscometer, which consists of a U-shaped glass tube held vertically. It is also known as a glass capillary viscometer. A liquid is allowed to flow through its capillary tube between two etched marks and the time of flow of the liquid is measured using a stopwatch.
What is the difference between rheometer and viscometer?
What’s the difference? Typically a viscometer employs a mechanical bearing that limits the speed and torque capabilities of the instrument, whereas a rheometer uses a low friction air bearing. A viscometer can offer portability for field or remote testing.
Can a rheometer measure viscosity?
Unlike a viscometer, which can only measure the viscosity of a fluid under a limited range of conditions, a rheometer is capable of measuring viscosity and elasticity of non-Newtonian materials under a wide range of conditions.
What does rheology measure?
To measure the rheological properties of a material, rheometers are used. They measure the torque and the deflection angle of the measuring bob. This means that in a viscosity measurement the rheometer presets a certain current that correlates to a defined torque. The speed is then measured.
What is the difference between rheology and viscosity?
Rheology is not a measure of viscosity but an area of physics focused on the study of a substance’s change in flow characteristics under applied stress or force. The term rheology modifier is being used erroneously to refer to chemicals that modify the viscosity of any material.
What is the relationship between rheology and viscosity?
Rheology is a general term referring to the science of studying flow and deformation of materials. Viscosity is defined as the resistance of a liquid to flow. For example, ketchup has a higher viscosity than water. An understanding of rheology and viscosity is essential to processing of polymers and coating.
What is viscosity in rheology?
The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress. It is a measure of the resistance of flow due to internal friction when one layer of fluid is caused to move in relationship to another layer.
What is difference between Newtonian and non-Newtonian fluid?
First, what is the difference between Newtonian and non-Newtonian fluids? Newtonian fluids have a constant viscosity that doesn’t change, no matter the pressure being applied to the fluid. Non-Newtonian fluids are just the opposite — if enough force is applied to these fluids, their viscosity will change.
What are examples of Newtonian fluids?
Water, air, alcohol, glycerol, and thin motor oil are all examples of Newtonian fluids over the range of shear stresses and shear rates encountered in everyday life. Single-phase fluids made up of small molecules are generally (although not exclusively) Newtonian.
Is coffee a Newtonian fluid?
Because coffee is shear thinning, it classifies as a non-Newtonian fluid and possibly explains why we spill coffee much more easily when walking with a cup of it. The faster we walk and jostle the cup, the lower the viscosity.
What are non-Newtonian fluids give examples?
Ketchup, for example, becomes runnier when shaken and is thus a non-Newtonian fluid. Many salt solutions and molten polymers are non-Newtonian fluids, as are many commonly found substances such as custard, honey, toothpaste, starch suspensions, corn starch, paint, blood, melted butter, and shampoo.
Are all fluids non Newtonian?
In reality most fluids are non-Newtonian, which means that their viscosity is dependent on shear rate (Shear Thinning or Thickening) or the deformation history (Thixotropic fluids).
What are the types of non Newtonian fluids?
Different types of non-Newtonian fluids
| Type of behaviour | Description |
|---|---|
| Thixotropic | Viscosity decreases with stress over time |
| Rheopectic | Viscosity increases with stress over time |
| Shear thinning | Viscosity decreases with increased stress |
| Dilatant or shear thickening | Viscosity increases with increased stress |
Is Jelly a non-Newtonian fluid?
Jelly is also a non-Newtonian fluid. It is a ‘colloid’ and it is closest to a liquid rather than a solid.