Positive displacement flow meters are devices used to measure the flow of liquids or gases by capturing a fixed volume of fluid and then releasing it. They work by using mechanical components, such as gears or pistons, that move in response to the flow, allowing for accurate measurement regardless of changes in pressure or temperature. These flow meters are commonly used in various industries, including oil and gas, water treatment, and food processing. Their design ensures high accuracy and repeatability, making them ideal for applications where precise flow measurement is essential.