A capillary viscometer is a device used to measure the viscosity of a fluid. It operates on the principle that the time it takes for a liquid to flow through a narrow tube, or capillary, is directly related to its viscosity. The longer the time taken, the higher the viscosity of the fluid. This method is commonly used in laboratories to assess the flow properties of various liquids. These viscometers are often made of glass and come in different designs, such as the U-tube or Ostwald types. They are essential tools in industries like petrochemicals, food, and pharmaceuticals, where understanding fluid behavior is crucial for quality control and product formulation.