If you are looking to determine the viscosity or thickness of a liquid, you will use either a viscometer or a rheometer. The former measures the viscosity under a single flow condition while the latter measures thicknesses that vary with the flow conditions. One specific viscometer is the capillary viscometer.
What Is a Capillary Viscometer?
A viscometer determines the thickness of a transparent or translucent fluid liquid by establishing how long it will take it to flow through a tube. The tube is small in diameter. This tube is called a capillary. Because temperature does effect the flow time, lab technicians will place the viscometer in a water bath in which the temperature is carefully controlled. Depending upon the liquid and the specific tests, technicians will alter the bath’s temperature and monitor the results.
A viscometer is generally employed to monitor Newtonian (but only a few non-Newtonian) fluids. Newtonian fluids include the many common commonly recognized liquids and gases e.g. water and air. A viscometer can determine these elements in both dilute solutions and suspensions. To be accurate the Reynolds number recorded must fall in the laminar region and not be transient or turbulent.
Basic Types of Capillary Viscometers
Capillary viscometers frequently inhabit laboratories. They come in several designs but two are more common. These are:
- U-Shaped (Ostwald) Viscometer: This is the most common. Within this category, Cannon-Fenske and Ubbelohde types are typical. Poiseuille’s Law, is eh most common principle at work.
- Falling Sphere Viscometers: A falling sphere is the means of measuring the viscosity of the fluid. At work is Stokes’ Law.
These two types of capillary viscometers have practical industrial applications.
Industrial Applications for Capillary Viscometers
Determining the viscosity of a substance, material or chemical is important. Understanding the specifics is essential when a company is examining what process conditions it can employ when the material. Viscosity affects the performance capabilities or levels of various processes including:
- Dipping
- Coating
- Piping
- Pumping
Moreover, viscosity can be a useful tool for quality control. They can help to monitor batch consistency in the various industries that employ this device. Among the more common ones are:
- Adhesives
- Asphalt
- Beverages
- Coatings
- Cosmetics
- Oil and other lubricants
- Paints
- Plastics
- Shampoo
- Toothpaste
- Wax
Capillary viscometers, in the right hands, become tools that is a tool critical in determining the thickness of any material that requires manipulation, transferring or stirring.
Capillary Viscometer
Choosing the right viscometer can be a complex process. It will rely on the characteristics and properties of the sample type and related factors. These include accuracy, microvolume capability, sample volume, temperature control and viscosity range. Before you decide on what type of capillary viscometer, make certain you take into consideration all the factors that will affect the purchase, including the budget.