Methods of testing oil viscosity

1) Falling Sphere Viscometer

Falling sphere viscometer is a simple instrument which used to measure the dynamics viscosity of the Newtonian fluid. Working principle of this falling sphere viscometer is very simple. It measure the time needed by a solid sphere to cover a certain vertical distance. This vertical free fall movement is inside the viscous fluid whose dynamic viscosity is needed to be measured. The apparatus simply consist of a cylindrical tube having starting and ending marks for vertical distance. Tube is filled with viscous fluid and stop watch is used to measure the time of sphere moving inside the tube. A simple thermometer and density-meter is used to measure the temperature and density of the fluid during before the experiment starts

2) Capillary Viscometer

Capillary viscometer is the simplest and easiest instrument and method available to measure the viscosity of the all Newtonian fluids and some of the Non-Newtonian fluids. This apparatus simply consists of a single piece of a specially design tube that has multiple shapes with each as it’s on diameter and length all integrated into one tube. Capillary viscometer measures viscosity of a fluid by allowing the fluid to pass through certain length of tube with constant diameter. The movement of fluid inside viscometer is due to its hydrostatic pressure. Time taken by the known volume of fluid to pass the specific marked length of the tube with constant diameter is used to calculate the viscosity of the fluid. Time is measure with the help of a stop watch and tubes has all necessary grading to show the start and end point of length.

3) Viscometer of Ubbelohde

Viscometer of Ubbelohde was name after its German inventor a chemist named Ubbelohde and its working principle is very much same as that of the capillary viscometer. It also uses a very much similar glass tube that allows the fluid to pass through a known length of tube. Time required to cover that know length of glass tube defines the viscosity of the fluid. Its use is recommended specifically for higher viscosity fluid (cellulosic polymer solutions). The main advantage of this instrument over the capillary viscometer is that the values obtained are independent of the total fluid volume used.


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