A capillary viscometer is a device used to measure the viscosity of a fluid. It operates by allowing a liquid to flow through a narrow tube, or capillary, and measuring the time it takes for the liquid to pass between two marked points. The viscosity is calculated based on the flow time and the characteristics of the capillary. These viscometers are commonly used in laboratories and industries to assess the flow properties of various liquids, including oils and polymers. They are essential for quality control and research, helping to ensure that fluids meet specific performance standards in applications like automotive and food processing.