Viscosity measurement

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Viscosity is the property of a substance; it is defined as the resistance offered between fluid layers.

Practically everyone has seen it, the rate of flow of water is faster than the rate of flow of oil this is because of viscous forces acting between the layers.

There are various methods to measure viscosity starting from conventional methods to modern methods.

  1. Capillary viscometer: These are also called Ostwald or ubbelohde viscometer on the honor of these scientists. Viscosity is measured by calculating the time taken for a volume of liquid to pass through the length of the capillary tube.
  2. Zahn Cup: Measures by observing the time it takes the volume of liquid to empty the cup through a small hole in the bottom of a container/cups. The Zahn cup is often used in the paint industry.
  3. Vibrational Viscometer: This device measures the damping of an oscillating electromechanical resonator immersed in a fluid. This technique is often used in-process to give continuous readings in a product stream, batch vessel, or in other process applications.
  4. Rotational Viscometer: Measures the torque required to revolve an object within the volume of liquid. This method is frequently used in quality control and production laboratories.
  5. Falling sphere Viscometer: In this method, a sphere of known density is dropped into the fluid sample and the time it takes for the sphere to fall to a specified point is recorded. This method has been used on ships to monitor the quality of the fuel going into the ship’s engine. 

Also, many modern methods are emerging as there is intense research going in the field of fluid dynamics.

One of the methods is a VROC viscometer in which pressure-driven using a pumping system that the laminar flow to push the liquid into a rectangular slot with pressure sensors, measuring the viscosity of a fluid through the change in pressure after passing each pressure sensor within the microchip.

Back to: Instrumentation and Control

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