DuNoüyRing

The DuNoüy ring is a laboratory instrument used to measure surface tension. It consists of a platinum ring suspended from a sensitive balance, typically a torsion balance. The ring is dipped into the liquid to be tested and then slowly lifted. As the ring is lifted, a film of the liquid forms between the ring and the bulk liquid. The force required to break this film is measured by the balance. This force, divided by the circumference of the ring, gives the surface tension of the liquid. The DuNoüy ring method is a widely accepted and reliable technique for determining surface tension due to its accuracy and relative simplicity. It is particularly useful for measuring the surface tension of liquids that are viscous or may contain surface-active agents. The instrument requires careful calibration and proper technique to obtain accurate results. Environmental factors such as temperature and humidity can also influence the measurements and need to be controlled. The platinum ring is often used because it is inert and can withstand a wide range of temperatures and chemical environments without reacting with the liquid being tested.