Positive displacement devices are mechanical systems that move fluids by trapping a fixed amount of liquid or gas and forcing it through the system. These devices operate by creating a vacuum or pressure that pushes the fluid into a designated area, ensuring a consistent flow rate regardless of the pressure in the system. Common examples include pumps and compressors. These devices are widely used in various industries, including oil and gas, food processing, and chemical manufacturing. Their ability to handle viscous fluids and maintain precise flow rates makes them essential for applications where accuracy and reliability are crucial.